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  • Articles  (485)
  • wheat  (294)
  • Zea mays  (193)
  • Springer  (485)
  • 1990-1994  (485)
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  • Articles  (485)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 3 (1990), S. 109-115 
    ISSN: 1432-2145
    Keywords: Zea mays ; Ear initials ; Kinetin ; Gibberellic acid ; Male and female flowers ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Young ears of maize were cultured in two different liquid media containing either kinetin (KN) or kinetin + gibberellic acid (KN + GA3) in order to manipulate stamen and gynoecium development. In KN medium, stamens developed and gynoecia aborted in the flowers of the cultured immature ears. In the KN + GA3 medium, however, ovaries with silks developed and stamens aborted. These differential morphological events were recorded with SEM photomicrographs at regular intervals after excision of ear inflorescences. In addition, the mitotic activity in the developing or aborting organs was determined over a 75-h period. It increased from 6% to 14% in developing organs (i.e. stamens in KN medium, and gynoecia in KN + GA3 medium) and gradually decreased to 1% in the degenerating organs (i.e. gynoecia in KN medium, and stamens in KN + GA3 medium) by 45 h of culture. The mitotic activity reached zero in degenerating flower organs by 75 h of culture. Whether these differential sensitivities to the exogenously applied members of these two plant growth regulator classes are unique to our in vitro system or reflect a more general control feature of in vivo inflorescences must await further clarification.
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  • 2
    Electronic Resource
    Electronic Resource
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    Sexual plant reproduction 4 (1991), S. 12-16 
    ISSN: 1432-2145
    Keywords: In vitro fertilization ; Egg cell ; Sperm cell ; Electrofusion ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electrofusion-mediated in vitro fertilization of maize using single sperm and egg cells was performed. Sperm cells were released from pollen grains after rupture of the latter by osmotic shock in the fusion medium (0.55 M mannitol). Egg cells were isolated by enzyme treatment (pectinase, pectolyase, hemicellulase, and cellulase) followed by mechanical isolation. The conditions generally used for the electrical fusion of protoplasts of somatic cells were also applied to the protoplasts of gametic cells of maize. Electrofusion was performed with single pairs of gametes under microscopic observation. The mean fusion frequency was 79%. Isolated egg cells of maize showed protoplasmic streaming during 22 days of culture, but they did not divide. However, after fusion of the sperm with the egg cells, these fused cells did develop, with a mean division frequency of 83%, and grew to multicellular structures. Egg cells and fusion products were cultivated with a maize feeder-cell system.
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  • 3
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    Springer
    Sexual plant reproduction 6 (1993), S. 239-243 
    ISSN: 1432-2145
    Keywords: Zea mays ; Sperm cell ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sperm cells are thought to be quiescent in pollen and activated upon pollen germination. To test this hypothesis, protein, RNA and DNA synthesis were assessed in Zea mays sperm cells at different times after isolation from pollen. Protein synthesis changed with time; while some proteins were found to be constitutive in both 0 and 24 h cells, others were synthesized and some disappeared. Overall, the number of proteins detected at 24 h doubled compared with freshly isolated cells. Incorporation of [3H]leucine in 24 h cells was about 50 times that in freshly isolated cells, and that of [5, 6-3H]uridine, about 7 times. Very low incorporation of [6-3H]thymidine into the cells was detected; there was no difference between freshly isolated and 24 h cells. It is possible that the differences in synthetic activity between freshly isolated and 24-h-old cells might correspond to sperm cell activation during pollen tube growth. If so, these metabolic changes may play an important role in fertilization.
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  • 4
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    Springer
    The journal of membrane biology 114 (1990), S. 133-142 
    ISSN: 1432-1424
    Keywords: Ca2+ transport ; plasma membrane ; Ca2+ pump ; pH gradient ; Ca2+/H+ antiporter ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Plasma membrane vesicles, which are mostly right side-out, were isolated from corn leaves by aqueous two-phase partitioning method. Characteristics of Ca2+ transport were investigated after preparing inside-out vesicles by Triton X-100 treatment.45Ca2+ transport was assayed by membrane filtration technique. Results showed that Ca2+ transport into the plasma membrane vesicles was Mg-ATP dependent. The active Ca2+ transport system had a high affinity for Ca2+(K m (Ca2+)=0.4 μm) and ATP(K m (ATP)=3.9 μm), and showed pH optimum at 7.5. ATP-dependent Ca2+ uptake in the plasma membrane vesicles was stimulated in the presence of Cl− or NO 3 − . Quenching of quinacrine fluorescence showed that these anions also induced H+ transport into the vesicles. The Ca2+ uptake stimulated by Cl− was dependent on the activity of H+ transport into the vesicles. However, carbonylcyanidem-chlorophenylhydrazone (CCCP) and VO 4 3− which is known to inhibit the H+ pump associated with the plasma membrane, canceled almost all of the Cl−-stimulated Ca2+ uptake. Furthermore, artificially imposed pH gradient (acid inside) caused Ca2+ uptake into the vesicles. These results suggest that the Cl−-stimulated Ca2+ uptake is caused by the efflux of H+ from the vesicles by the operation of Ca2+/H+ antiport system in the plasma membrane. In Cl−-free medium, H+ transport into the vesicles scarcely occurred and the addition of CCCP caused only a slight inhibition of the active Ca2+ uptake into the vesicles. These results suggest that two Ca2+ transport systems are operating in the plasma membrane from corn leaves, i.e., one is an ATP-dependent active Ca2+ transport system (Ca2+ pump) and the other is a Ca2+/H+ antiport system. Little difference in characteristics of Ca2+ transport was observed between the plasma membranes isolated from etiolated and green corn leaves.
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  • 5
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    The journal of membrane biology 119 (1991), S. 277-288 
    ISSN: 1432-1424
    Keywords: Ca2+-activated K+ current ; Ca2+ channel ; Zea mays ; 1,4-dihydropyridine ; phenylalkylamine ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The voltage- and time-dependent K+ current,I K + out , elicited by depolarization of corn protoplasts, was inhibited by the addition of calcium channel antagonists (nitrendipine, nifedipine, verapamil, methoxyverapamil, bepridil, but not La3+) to the extracellular medium. These results suggested that the influx of external Ca2+ was necessary for K+ current activation. The IC50, concentration of inhibitor that caused 50% reduction of the current, for nitrendipine was 1 μm at a test potential of +60 mV following a 20-min incubation period. In order to test whether intracellular Ca2+ actuated the K+ current, we altered either the Ca2+ buffering capacity or the free Ca2+ concentration of the intracellular medium (pipette filling solution). By these means,I K + out could be varied over a 10-fold range. Increasing the free Ca2+ concentration from 40 to 400nm also shifted the activation of the K+ current toward more negative potentials. Maintaining cytoplasmic Ca2+ at 500nm with 40nm EGTA resulted in a more rapid activation of the K+ current. Thus the normal rate of activation of this current may reflect changes in cytoplasmic Ca2+ on depolarization. Increasing intracellular Ca2+ to 500nm or 1 μm also led to inactivation of the K+ current within a few minutes. It is concluded thatI K + out is regulated by cytosolic Ca2+, which is in turn controlled by Ca2+ influx through dihydropyridine-, and phenylalkylamine-sensitive channels.
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  • 6
    ISSN: 1432-203X
    Keywords: Zea mays ; Matrix-associated ; DNA ; repetitive sequences ; DNA loops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to elucidate some features of the topological organization of DNA within the plant nucleus, DNA fragments involved in the attachment of the DNA loops to the nuclear matrix in maize were studied. The matrix-associated DNA from dry embryo and meristematic cells after extensive digestion with DNase I and high salt treatment was about 2% of the total DNA, sized within the range of 50 and 250 bp. This DNA was found to be enriched in repetitive DNA sequences, both for nuclei from dry embryo and meristematic cells. The loop size of the DNA in cells of Zea mays appeared to be between 5 and 25 kbp.
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  • 7
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    Plant cell reports 12 (1993), S. 564-568 
    ISSN: 1432-203X
    Keywords: Zea mays ; In vitro culture ; Isolated microspores ; Pollen development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An in vitro method to simulate pollen development was developed in maize (Zea mays L.). Microspores at the late uninucleate to early binucleate stage were isolated and cultured under various conditions. Cell viability, starch content and the formation of the three nuclei as found in normal mature pollen were monitored during the course of the culture. Media composition was modified in order to promote starch accumulation and frequency of mitosis, while maintaining the viability of the microspores. Under the best conditions, up to 12% of the microspores matured in vitro into trinucleate, starch-filled viable pollen grains which were unable to germinate or produce seeds. At different stages during in vitro maturation, proteins patterns were analyzed and compared with their in vivo equivalent and the patterns were only partially similar.
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  • 8
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    Plant cell reports 12 (1993), S. 607-611 
    ISSN: 1432-203X
    Keywords: Transient expression ; Particle bombardment ; Tassel primordia ; In vitro culture ; Anthers ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maize (Zea mays L.) tassel primordia were used as a target for particle bombardment, to assess the possibility of introducing foreign DNA into male reproductive structures. Transient expression of the β-glucuronidase gene (GUS) or anthocyanin marker genes (C1 and B-Peru) driven by the CaMV 35S promoter was obtained in tassel primordia 24h after bombardment. Gold particles coated with DNA reached stamen primordia tissues, which eventually form the anthers and pollen. Bombarded tassels were also cultured in vitro and GUS activity was detected in the vascular tissue of mature anthers that developed within 4 weeks. This new approach represents a preliminary step toward pollen mediated transformation.
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  • 9
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    Plant cell reports 12 (1993), S. 648-651 
    ISSN: 1432-203X
    Keywords: chromosome doubling ; Zea mays ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Anther-derived calli of corn were treated with 10 μM pronamide for 2, 3 and 4 days. The ploidy level of the calli was then evaluated using flow cytometry, at different times after the treatment. Untreated haploid calli did not change in ploidy level for 97 days but by 466 days, there were up to 50% diploid or higher ploidy cells thus showing that spontaneous doubling may occur during corn calli subculture with this genotype. Pronamide treatment did increase the percentage of diploid and tetraploid cells and by 466 days, all of the lines showed an additional change toward higher ploidy levels. This change may be due to spontaneous chromosome doubling or to differential cell cycle times of cells with different ploidy levels. The ploidy level of plants regenerated from the cultures was determined by counting the guard cell chloroplast numbers and the correlation with the ploidy level of the cultures was r2=0.84. These studies show that pronamide treatments can increase haploid maize callus chromosome numbers and that spontaneous chromosome doubling can occur with time in maize callus.
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  • 10
    ISSN: 1432-203X
    Keywords: wheat ; rye ; embryogenesis ; growth ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.
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  • 11
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    Plant cell reports 11 (1992), S. 535-539 
    ISSN: 1432-203X
    Keywords: Zea mays ; in vitro culture ; in vitro pollen ; pollen germination ; fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maturation of maize pollen was obtained in male reproductive structures cultured in vitro. Immature tassels containing microspores at the mid-uninucleate to late-binucleate stage of development were excised and spikelets, anthers, and/or isolated microspores were cultured on a medium capable of supporting pollen maturation. Microspore mitosis, culminating in the production of starch-filled, trinucleate pollen capable of germination, was observed after 7–15 days, depending on the genotype and stage at which the cultures were initiated. Up to 100%, 70%, and 20% of the cultured spikelets, anthers, and isolated microspores, respectively, produced mature pollen, which germinated, however, at different frequencies (i.e., spikelets, 50–70%; anthers, 5–10%; microspores, 〈1%). Mature kernels were produced following fertilization with pollen from cultured spikelets and anthers. These procedures provide methods for the in vitro manipulation of a significant phase of the maize life cycle.
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  • 12
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    Plant cell reports 11 (1992), S. 567-570 
    ISSN: 1432-203X
    Keywords: Microspore ; Electroporation ; Transformation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability to deliver and detect reporter gene activity in maize microspores was tested. Tested expression vectors contained the chloramphenicol acetyl transferase (CAT) gene and one of the following promoter-intron combinations: 1) cauliflower mosaic virus (CaMV 35S), 2) CaMV 35S + maize alcohol dehydrogenase 1 intron 6 (Adh1-I6), 3) maize alcohol dehydrogenase 1 + intron 1 (Adh1-I1), or 4) maize ubiquitin 1 + intron 1 (Ubiq 1-I1) promoter + intron. The expression vectors were delivered into maize microspores using electroporation or polyethylene glycol (PEG). Both methods were effective for delivering free DNA into microspores. Although all four promoters were active in maize protoplasts, only two promoters were active in maize microspores. The CaMV 35S and the Adh1 promoters did not promote gene expression in maize microspore. The CaMV 35S + Adh1-I6 and Ubiq1-I1 promoters produced high levels of CAT activity in maize microspores.
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  • 13
    ISSN: 1432-2048
    Keywords: Anthocyanin ; Cold stress ; mRNA ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in anthocyanin content and transcript abundance for genes whose products function in general phenylpropanoid metabolism and the anthocyanin pathway were monitored in maize (Zea mays L.) seedlings during short-term, low-temperature treatment. Anthocyanin and mRNA abundance in sheaths of maize seedlings increased with the severity and duration of cold. Anthocyanin accumulation was found in all tested lines that were genotypically capable of any anthocyanin production. Within 24 h of transferring 7-d maize (B37N) seedlings to 10° C, phenylalanine ammonia-lyase (Pal) (EC 4.3.1.5)-homologous and chalcone synthase (C2) (EC 2.3.1.74) transcript levels increased at least 8- and 50-fold, respectively, and 4-coumarate:CoA ligase (4Cl) (EC 6.2.1.12)-homologous and chalcone isomerase (Chi) (EC 5.5.1.6)-homologous transcripts increased at least 3-fold over levels in unstressed plants. Time-course studies showed thatPal (EC 4.3.1.5) andC2-transcript levels remained relatively constant for the first 12 h of cold stress, dramatically increased over the next 12 h, and declined to pretreatment levels within 2 d of returning coldstressed seedlings to ambient (25° C) temperature. Transcripts4Cl (EC 6.2.1.12) andChi (EC 5.5.1.6) increased in abundance within 6 h of cold stress, exhibited no further increase over the next 36 h, and declined to pretreatment levels upon returning seedlings to 25° C. Transcripts homologous to two regulatory (R, C1) and three structural (A1,A2, andBz2) anthocyanin genes increased at least 7- to 10-fold during cold treatment, exhibiting similar kinetics of accumulation as forPal (EC 4.3.1.5) andC2 transcripts. Transcripts encoded byBz1, the anthocyanin structural gene for UDP:glucose-flavonol glucosyltransferase (EC 2.4.1.91), were relatively abundant in control tissues and exhibited only a transient increase during the cold period. Our studies suggest that the genes of the anthocyanin biosynthetic pathway can be consideredcor (Cold-Regulation) genes, and because this pathway is well defined, it is an excellent subject for characterizing plant molecular responses to low temperatures.
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  • 14
    ISSN: 1432-2242
    Keywords: Denaturing gradient gel electrophoresis ; DNA polymorphism ; Restriction fragment length polymorphism ; Zea mays ; B-A translocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have used denaturing gradient gel electrophoresis (DGGE) to identify genomic DNA polymorphism in maize (Zea mays L.). DGGE probes detect polymorphism in maize at a frequency comparable to the incidence of restriction fragment length polymorphism (RFLP). Probes identifying polymorphism were mapped to maize chromosome arms by utilizing DGGE and maize lines carrying B-A chromosomal translocations. The methods for library construction, probe screening, and genome analysis, described here for maize, can also be applied to the genomic analysis of other organisms.
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  • 15
    ISSN: 1432-2242
    Keywords: Zea mays ; Chromosome doubling ; Amiprophos methyl ; Pronamide ; Oryzalin ; Trifluralin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four antimicrotubule herbicides, amiprophosmethyl (APM), pronamide, oryzalin, and trifluralin, were evaluated for their ability to induce chromosome doubling in anther-derived, haploid maize callus. Effects of various herbicide treatments on the growth and regenerative capacity of callus along with the ploidy and seed set of regenerated plants were determined. Flow cytometric analysis was also used to measure changes in ploidy levels of callus cells following treatments. More than 50% of the cells were doubled in chromosome number after the haploid callus was treated with 5 or 10 μ M APM or 10 μ M pronamide for 3 days. A similar proportion of plants regenerated from the treated callus produced seed upon self-pollination. APM and pronamide did not inhibit callus growth at these concentrations and the treated callus retained a high plant regeneration capacity. Oryzalin very effectively induced chromosome doubling, but severely inhibited the growth of regenerable callus and plant regeneration. Trifluralin induced chromosome doubling in a small proportion of cells at lower concentrations (0.5 and 1 μ M), however, at a higher concentration (5 μM) it inhibited callus growth and plant regeneration. The results indicate that APM and pronamide may be useful agents for inducing chromosome doubling of anther-derived maize haploid callus at very low concentrations.
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  • 16
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    Theoretical and applied genetics 81 (1991), S. 635-640 
    ISSN: 1432-2242
    Keywords: Catalase null ; Zea mays ; Catalase transcript ; Transposable element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The molecular basis for a shorter Cat2 transcript in maize lines null for the CAT-2 catalase iso/yme was investigated using cDNA libraries and genomic DNA blots. Sequence comparison of partial Cat2 cDNAs obtained from two CAT-2 null lines and a wild-type CAT-2 encoding cDNA showed that the Cat2 null transcripts diverged from the wild-type transcript but remained homologous to each other. Genomic DNA blots indicated that the missing portion of the transcript is present in the genomes of lines null for the CAT-2 isozyme. Differences in the hybridization patterns of normal and null lines were revealed when genomic DNA blots were probed with the full-length Cat2 cDNA, a Cat2 gene-specific probe, and a “null sequence” probe. Together, the DNA blotting results suggest that a rearrangement of the Cat2 gene has occurred in the CAT-2 null lines. The available data suggest that the CAT-2 null mutation in maize is due to a DNA insertion into the Cat2 gene.
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  • 17
    ISSN: 1432-2242
    Keywords: Zea mays ; Aspartate kinase Threonine-overproducing mutants ; Lysine ; Methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aspartate-derived amino-acid pathway leads to the production of the essential amino-acids lysine, methionine, threonine and isoleucine. Aspartate kinase (AK) is the first enzyme in this pathway and exists in isoforms that are feedback inhibited by lysine and threonine. Two maize (Zea mays L.) threonine-overproducing, lysine-insensitive AK mutants (Ask1-LT19 and Ask2-LT20) were previously isolated. The present study was conducted to determine the map location of Ask2 and to examine the amino-acid profiles of the Ask mutants. The threonine-overproducing trait conferred by Ask2-LT20 was mapped to the long arm of chromosome 2. Both mutants exhibited increased free threonine concentrations (nmol/mg dry weight) over wild-type. The percent free threonine increased from approximately 2% in wild-type kernels to 37–54% of the total free amino-acid pool in homozygous mutant kernels. Free methionine concentrations also increased significantly in homozygous mutants. Free lysine concentrations were increased but to a much lesser extent than threonine or methionine. In contrast to previous studies, free aspartate concentrations were observed to decrease, indicating a possible limiting factor in threonine synthesis. Total (free plus protein-bound) amino-acid analyses demonstrated a consistent, significant increase in threonine, methionine and lysine concentrations in the homozygous mutants. Significant increases in protein-bound (total minus free) threonine, methionine and lysine were observed in the Ask mutants, indicating adequate protein sinks to incorporate the increased free amino-acid concentrations. Total amino-acid contents (nmol/kernel) were approximately the same for mutant and wild-type kernels. In five inbred lines both Ask mutations conferred the threonine-overproducing phenotype, indicating high expressivity in different genetic backgrounds. These analyses are discussed in the context of the regulation of the aspartate-derived amino-acid pathway.
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  • 18
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    Cellular and molecular life sciences 46 (1990), S. 1016-1017 
    ISSN: 1420-9071
    Keywords: In vitro absorption ; calcium ; wheat ; Bengal gram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The in vitro absorption of calcium from the duodenum was significantly less in a group of rats fed on a wheat diet than in a group fed a wheat and Bengal gram (70∶30) diet.
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  • 19
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    Cellular and molecular life sciences 50 (1994), S. 571-575 
    ISSN: 1420-9071
    Keywords: Ancient DNA ; archaeobotany ; carbonized grain ; DNA sequences ; glutenin alleles ; seed proteins ; Triticum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.
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  • 20
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    Cellular and molecular life sciences 46 (1990), S. 971-972 
    ISSN: 1420-9071
    Keywords: Zea mays ; inhibitor of the oxidation of catechin ; root release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary When the specific activities of the catechin oxidases (catechin as the substrate) which were released from the roots of the seedlings of alfalfa, tomato, wheat, lettuce and corn were compared, it was found that the oxidizing activity was absent from the root exudate of corn seedlings. A 6.3 kDa protein was purified from the root exudate of corn seedlings and in the presence of this protein, the oxidation of catechin was inhibited. This inhibitor is responsible for the inability of the root exudate of corn seedlings to oxidize catechin.
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  • 21
    ISSN: 1432-0983
    Keywords: Chloroplast DNA ; Junction between small single copy and inverted repeat regions ; Zea mays ; Grammineae ; ndhH gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The junctions JSA and JSB between the two inverted repeat regions IRA and IRB and the small single copy region of the maize chloroplast DNA have been identified by DNA sequencing. The JSA junction coincides with the initiation codon of the ndhH gene which is encoded by the adjacent region of the small single copy region. A comparison with the plastomes of rice, rye, tobacco and liverwort shows that linkage of this junction with the ndhH gene is specific for gramminean species. The amino acid sequences deduced from the ndhH genes show conserved histidine and cysteine residues which are likely to form a metal-binding domain.
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  • 22
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    Biology and fertility of soils 15 (1993), S. 249-252 
    ISSN: 1432-0789
    Keywords: N fertilizer requirement ; Nitrification ; Zea mays ; N mineralization ; Lime ; Soil pH ; Nitrate-N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The application of NH inf4 su+ -based fertilizers to soils slowly lowers soil pH, which in turn decreases nitrification rates. Under these conditions nitrification and N mineralization may be reduced. We therefore investigated the impact of liming fertilizer-acidified soils on nitrification and N mineralization. Soil samples were collected in the spring of 1987 from a field experiment, initiated in 1980, investigating N, tillage, and residue management under continuous corn (Zea mays L.). The pH values (CaCl2) in the surface soil originally ranged from 6.0 to 6.5. After 6 years the N fertilizer and tillage treatments had reduced the soil pH to values that ranged between 3.7 and 6.2. Incubation treatments included two liming rates (unlimed or SMP-determined lime requirement), two 15N-labeled fertilizer rates (0 or 20 g N m-2), and three replicates. Field-moist soil was mixed with lime and packed by original depth into columns. Labeled-15N ammonium sulfate in solution was surface-applied and columns were leached with 1.5 pore volumes of deionized water every 7 days over a 70-day period. Nitrification occurred in all pH treatments, suggesting that a ferilizer-acidified soil must contain a low-pH tolerant nitrifier population. Liming increased soil pH values (CaCl2) from 3.7 to 6.2, and increased by 10% (1.5 g N m-2) the amount of soil-derived NO3 --N that moved through the columns. This increase was the result of enhanced movement of soil-derived NO3 --N through the columns during the first 14 days of incubation. After the initial 14-day period, the limed and unlimed treatments had similar amounts of soil N leaching through the soil columns. Lime increased the nitrification rates and stimulated the early movement of fertilizer-derived NO3 --N through the soil.
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  • 23
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    Biology and fertility of soils 17 (1994), S. 1-8 
    ISSN: 1432-0789
    Keywords: Ammonium excretion ; Azospirillum brasilense ; Auxine ; 2,4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Maize ; Zea mays ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize seedlings develop nodule-like tumour knots (para-nodules) along primary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Inoculated NH 4 + -excreting Azospirillum brasilense cells were shown to colonize these tumours, mostly intracellularly, promoting a high level of N2 fixation when microaerophilic conditions were imposed. The nitrogenase activity inside the para-nodules was less sensitive to free O2 than in non-para-nodulating roots. Both light and electron microscopy showed a dense bacterial population inside intact tumour cells, with the major part of the cell infection along a central tumour tissue. The bacteria colonized the cytoplasm with a close attachment to inner cell membranes. In an auxin-free growth medium, young 2,4-D-induced para-nodules grew further to become mature differentiated root organs in which introduced bacteria survived with a stable population. These results provide evidence that gramineous plants are potentially able to create a symbiosis with diazotrophic bacteria in which the NH 4 + -excreting symbiont will colonize para-nodule tissue intracellularly, thus becoming well protected.
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    Biology and fertility of soils 18 (1994), S. 228-230 
    ISSN: 1432-0789
    Keywords: Fine root ; Root litter ; Biofertiliser ; Leucaena leucocephala ; Trigonella foenum-graecum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficacy ofLeucaena leucocephala root litter as a natural biological fertiliser was assessed usingZea mays as a test plant. Up to 8% of the fine roots of the plants constituted root litter. This fine root litter was better than that ofTrigonella foenum-graecum at increasing the growth and productivity ofZea mays. The root litter increased the growth of maize shoots more than the growth of roots. This appears to be a general phenomenon when plant nutrients are insufficient, as in the present study.
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  • 25
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    Theoretical and applied genetics 81 (1991), S. 185-188 
    ISSN: 1432-2242
    Keywords: Zea mays ; Recombination ; A1 locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We find that recombination between two alleles of the maize A1 locus that contain transposon insertions at known molecular positions can occur at 0.04–0.08 cM per kbp (centimorgan per kilobase pair), which is two orders of magnitude higher than the recombination rate for the whole maize genome. It is however, close to the rates found within the bronze locus, another maize structural gene for which both genetic and molecular data are available. This observation supports the idea that the genome consists of regions that are highly recombinogenic — in some cases, at least, structural genes — interspersed with regions that are less recombinogenic.
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  • 26
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    Theoretical and applied genetics 81 (1991), S. 162-165 
    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Stability ; Maize ; Zea mays ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genotype x environment (GE) interaction encountered in experiments complicates genotype selection and varietal recommendation. The integration of yield and stability of genotypes into a single parameter may make selection and recommendation easier. Kang developed a rank-sum method that allows selection for both yield and the stability variance statistics (σ i 2 or s i 2 ) of Shukla. The objective of this research was to compare the rank-sum selection method to selection based on yield alone in five international maize (Zea mays L.) yield trials. Ranks were assigned for yield (the highest mean yield received a rank of 1) and for σ i 2 and s i 2 (the lowest value received a rank of 1). The yield and σ i 2 ranks and/or the yield and s i 2 ranks for each genotype were summed. Each trial contained two reference entries (REs). Yield rank or rank-sum of each genotype was compared to yield rank or rank-sum of the best RE (BRE). GE interaction was significant for all trials. Heterogeneity in the GE interaction due to the linear effect of a covariate (differences in fertility and/or cultural practices) was significant in Trials 1, 2, and 5. Overall, in all trials, 29 genotypes were selected on the basis of yield alone. On the basis of σ i 2 and yield rank-sum, 32 genotypes were identified, with 11 being lower yielding than the 29 yield-based selections. On the basis of s i 2 and yield rank-sum, 31 genotypes were selected, with 11 being lower yielding than the yield-bases selections. Obviously, yield is sacrificed when the rank-sum method is used in the selection process. However, selection based on yield alone may not be adequate when GE interaction is significant because of testing in diverse environments.
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    Theoretical and applied genetics 81 (1991), S. 227-232 
    ISSN: 1432-2242
    Keywords: Callus cultures ; RFLP ; Zea mays ; Oryza sativa ; Regeneration ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tissue culture of the Zea mays inbred line A188 resulted in the regeneration of plants having a high level of phenotypic variation compared to seed-grown control plants. To determine how such variation was induced and whether this could be related to specific in vitro culture methods, callus cultures were established and maintained on different, commonly used culture media. Plants were regenerated and the genomic DNA of callus cultures and regenerants analysed for RFLP differences. The results show that regardless of the gene probe used, callus formation resulted in significant deviations from the DNA pattern normally found in seed-grown control plants. Alterations in gene copy number also occurred. As differentiation and organogenesis began, the level of DNA variation fell, and most of the regenerated plants showed a genetic similarity to the controls; those with RFLP differences were the somaclonal variants.
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    Theoretical and applied genetics 86 (1993), S. 975-984 
    ISSN: 1432-2242
    Keywords: Chemiluminescence ; Genotyping costs ; RAPD ; RFLP ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three molecular marker protocols, chemiluminescent restriction fragment length polymorphisms (c-RFLPs), radioactivity-based restriction fragment length polymorphisms (r-RFLPs), and randomly amplified DNA polymorphisms (RAPDs) were compared in terms of cost and time efficiency. Estimates of cost of supplies and time requirements were obtained from simulations of maize (Zea mays L.) genotyping experiments utilizing protocols currently in use. The increase in total cost with increasing numbers of individuals genotyped and markers analyzed is higher for RAPDs than for RFLPs. RAPDs were generally found to be more cost and time efficient for studies involving small sample sizes, while RFLPs have the advantage for larger sample sizes. Because of the shorter exposure times involved, c-RFLPs require less time than r-RFLPs to obtain a given amount of information. Variations in the protocols, such as number of re-uses of Southern blots or cost of Taq DNA polymerase per reaction of amplification, also affect the relative merits of RAPDs and RFLPs. Two examples were analyzed where molecular markers are used: a germ plasm survey and quantitative trait loci (QTL) mapping in a segregating population. No protocol was found to be the most cost and time efficient over the entire range of sample sizes and number of marker loci studied.
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  • 29
    ISSN: 1432-2242
    Keywords: Sorghum ; Zea mays ; Phylogeny rDNA sequence
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    Notes: Abstract The phylogenetic relationships of the genus Sorghum and related genera were studied by sequencing the nuclear ribosomal DNA (rDNA) internal transcribed spacer region (ITS). DNA was extracted from 15 Sorghum accessions, including one accession from each of the sections Chaetosorghum and Heterosorghum, four accessions from Parasorghum, two accessions from Stiposorghum, and seven representatives from three species of the section Sorghum (one accession from each of S. propinquum and S. halepense, and five races of S. bicolor). The maize (Zea mays) line, H95, and an accession from Cleistachne sorghoides were also included in the study. Variable nucleotides were used to construct a strict consensus phylogenetic tree. The analyses indicate that S. propinquum, S. halepense and S. bicolor subsp. arundinaceum race aethiopicum may be the closest wild relatives of cultivated sorghum; Sorghum nitidum may be the closest 2n=10 relative to S. bicolor, the sections Chaetosorghum and Heterosorghum appear closely related to each other and more closely related to the section Sorghum than Parasorghum; and the section Parasorghum is not monophyletic. The results also indicate that the genus Sorghum is a very ancient and diverse group.
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  • 30
    ISSN: 1432-2242
    Keywords: Zea mays ; Opaque-2 ; RFLPs Marker-assisted selection
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    Notes: Abstract Quality Protein Maize (QPM) is a name given to genetically modified opaque-2 maize with hard endosperm. The opaque-2 mutation conditions a reduction in the amount of zein seed storage protein; zeins are deficient in the essential amino acids lysine and tryptophan, and mutant seed have a higher nutritional value. To utilize the potential of opaque-2 maize, elite inbreds can be converted to o2/o2 forms and subsequently to hard endosperm opaque-2. Since opaque-2 is recessive and endosperm specific, conventional backcross procedures to convert elite inbreds to opaque-2 forms are inefficient. To alleviate this problem, a marker-assisted selection procedure was developed for the Texas A&M University Quality Protein Maize breeding program. Hybridization of an O2 cDNA probe to blots of DNA from plants carrying O2 and o2 alleles showed that restriction fragment length polymorphisms (RFLPs) exist between the W64A o2 allele and O2 alleles of Mo17 and TX5855 inbred lines. To identify the opaque2 genotypes in segregating populations, an RFLP marker assay combining the O2 cDNA probe and HindIII-digestion of genomic DNA was developed. The effectiveness of the O2 RFLP marker assay was tested under field conditions using F2 and backcross populations of several hard endosperm opaque-2 lines. A comparison of the genotypes identified by RFLP analysis with the seed phenotypes of the next generation indicated that this procedure is accurate and can be used for identifying O2/O2, O2/o2, and o2/o2 genotypes of individual juvenile plants in breeding populations.
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    Theoretical and applied genetics 80 (1990), S. 705-711 
    ISSN: 1432-2242
    Keywords: Zea mays ; Catalase ; Gene expression ; Pollen ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The expression of the Cat and Sod genes encoding the multiple catalases and superoxide dismutases in maize has been studied in maize pollen at anther dehiscence. Pollen from three catalase activity variant inbred lines was examined. Zymorgram analysis, immunoassays, and RNA blots show that, in the lines used, only the CAT-1 catalase isozyme is expressed in mature pollen; the CAT-2 and CAT-3 isozymes are not. The data presented further demonstrate that the Cat1 gene is transcribed and translated after tetrad formation. The relative protein levels of the various superoxide dismutase (SOD) isozymes appear to be similar in pollen and scutella, and correspond to the relatively low levels observed for the different Sod transcripts in these tissues. The presence of “double” transcripts for Sod3 and Sod4A is discussed.
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  • 32
    ISSN: 1432-2242
    Keywords: Zea mays ; Parentage determination ; Varietal identification ; Genetic polymorphisms ; Genetic markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using a novel procedure based on the polymerase chain reaction, we have developed a rapid, efficient, and economical method for identifying plant genotypes. The arbitrarily primed polymerase chain reaction (AP-PCR) generates reproducible fingerprints from any organism, without the need for DNA sequence information. These fingerprints include DNA fragment polymorphisms that can be (1) used for varietal identification and parentage determination, (2) followed in segregating populations produced by crosses, (3) used as markers for the construction of genetic maps, and (4) used to generate dendograms of phylogenetic relationships, especially at the intraspecific level. AP-PCR requires only minute quantities of DNA (10–25 ng per reaction) and therefore can be used in situations in which DNA is limiting. We demonstrate the use of AP-PCR to identify inbred parents of hybrid maize plants in double-blind experiments.
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  • 33
    ISSN: 1432-2242
    Keywords: Zea mays ; Restriction fragment length polymorphisms (RFLPs)-Phosphorus (P) stress-quantitative trait loci (QTLs)
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    Topics: Biology
    Notes: Summary An understanding of the genetic nature underlying tolerance to low-phosphorus (low-P) stress could aid in the efficient development of tolerant plant strains. The objective of this study was to identify the number of loci in a maize (Zea mays L.) population segregating for tolerance to low-P stress, their approximate location, and the magnitude of their effect. Seventy-seven restriction fragment length polymorphisms (RFLPs) were identified and scored in a maize F2 population derived from a cross between line NY821 and line H99. The F2 individuals were self-pollinated to produce F3 families. Ninety F3 families were grown in a sand-alumina system, which simulated diffusion-limited, low-P soil conditions. The F3 families were evaluated for vegetative growth in a controlled-environment experiment. To identify quantitative trait loci (QTLs) underlying tolerance to low-P stress, the mean phenotypic performances of the F3 families were contrasted based on genotypic classification at each of 77 RFLP marker loci. Six RFLP marker loci were significantly associated with performance under low-P stress (P〈0.01). One marker locus accounted for 25% of the total phenotypic variation. Additive gene action was predominant for all of the QTLs identified. Significant marker loci were located on four separate chromosomes representing five unlinked genomic regions. Two marker loci were associated with an additive by additive epistatic interaction. A multiple regression model including three marker loci and the significant epistatic interaction accounted for 46% of the total phenotypic variation. Heterozygosity per se was not predictive of phenotypic performance.
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    Theoretical and applied genetics 84 (1992), S. 798-802 
    ISSN: 1432-2242
    Keywords: Zea mays ; C-banding ; Cell size ; Chloroplast number ; Cold tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary C-band number, guard cell length, and chloroplast number per guard cell were determined for eight maize populations. These populations consisted of maize selected for cold tolerance at the University of Nebraska as well as the original unselected populations. The genome size of these populations had previously been determined. C-band number fluctuated concertedly with the changes in genome size indicating that deletions and additions of constitutive heterochromatin occurred during selection, resulting in altered genome sizes. Guard cell size of all the cold tolerant populations was greater than the cell size of the respective nonselected populations. Chloroplast number per guard cell was also higher in all the cold tolerant populations than in their parental populations, but the increases were not statistically significant. The results indicate that changes in genome size that occurred during selection for cold tolerance are the result of changes in amounts of C-band heterochromatin and that the selection process results in an increase in cell size in the cold tolerant populations.
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    Theoretical and applied genetics 89 (1994), S. 259-264 
    ISSN: 1432-2242
    Keywords: RFLP ; Bootstrap ; Sampling variance ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Knowledge of genetic relationships among genotypes is useful in a plant breeding program because it permits the organization of germplasm and provides for more efficient sampling. The genetic distance (GD) among genotypes can be estimated using random restriction fragment length polymorphisms (RFLPs) as molecular markers. Knowledge of the sampling variance associated with RFLP markers is needed to determine how many markers are required for a given level of precision in the estimate of GD. The sampling variance for GD among all pairs of 37 maize (Z. mays L.) inbred lines was estimated from 1202 RFLPs. The 1202 polymorphisms were generated from 251 enzyme-probe combinations (EPC). The sampling variance was used to determine how large a sample of RFLPs was required to provide a given level of precision. The coefficient of variation (CV) associated with GD has a nearly linear relationship between its expected standard deviation and mean. The magnitude of the decrease in the mean CV for GD with increasing numbers of bands was dependent upon the sampling unit; e.g., individual polymorphic bands vs EPC, and the degree of relatedness among the inbreds compared. The rate of reduction in mean CV with increasing sample size was the same regardless of the restriction enzyme used, BamHI, EcoRI or HindIII, when the bootstrap sampling units were individual polymorphic bands. In constrast, although the rate of reduction (slopes) was the same, the intercepts of the mean CVs were different when EPCs were used as the bootstrap sampling unit. This difference was due to the higher number of bands per EPC in BamHI (4.94) compared with EcoRI (4.83) and HindIII (4.63).
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  • 36
    ISSN: 1432-2048
    Keywords: Ammonium compartmentation ; Cytoplasm ; Vacuole ; Zea mays
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    Notes: Abstract We show that the pH dependence of the base-catalysed exchange rate of the ammonium ion provides a basis for discriminating between the cytoplasmic and vacuolar pools of ammonium in plant tissues. In vivo, 14N-nuclear magnetic resonance spectra were recorded with and without 1H-decoupling and information on the subcellular distribution of NH 4 + was obtained from a lineshape analysis of the 1H-coupled spectrum. We applied this method to maize (Zea mays L.) root tissues and found that: (i), the cytoplasmic ammonium concentration was low, which was in accord with the large activity of glutamine synthetase present in the roots; and (ii), inhibition of glutamine synthetase with methionine sulphoximine increased the cytoplasmic ammonium concentration, and led to the appearance of ammonium in the xylem sap.
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    Sexual plant reproduction 3 (1990), S. 160-169 
    ISSN: 1432-2145
    Keywords: Pollen ; In vitro germination ; Microinjection ; In vitro fertilization ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The manipulation of single pollen grains of maize was studied. The effects of delivering substances both locally to the grain wall, tube or tip by a microcapillary and directly into the pollen grain by microinjection, and single grain pollination were investigated. Germination was induced by adding small amounts of water locally to the grains with either a microcapillary or with a waterdelivering emulsion without any other ingredients in the medium. The grains were overlayered by mineral or silicone oil so that tube growth proceeded without the grains bursting. There was no apparent penetration of high-molecular-weight substances (FITC-dextran, ethidium bromide labelled DNA) into the living grain either before or after pollination. Neither could the penetration of these substances be detected in both dry, viable and hydrated grains, tubes and tube tips, with or without treatment with Triton X-100 and dimethyl sulfoxide. By microinjection, however, the delivery of high-molecular-weight substances into grains was possible. Such injected grains successfully pollinated stigmas of cultured ear segments. Pollination with pore-injected grains was most efficient (mean 26%). No difference in fertilization rates between mass pollination (mean 41%) and single grain pollination (mean 39%) could be found. A mean fertilization rate of 29% could be obtained after microinjection. Seedlings developed 3 weeks after being pollinated by means of the in vitro pollination and fertilization method.
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    Sexual plant reproduction 5 (1992), S. 224-226 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Polyembryony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two types of cleavage polyembryony are described in the inbred line VIR 17 of maize. Suspensorial embryony was observed to occur spontaneously. Typical cleavage of the zygotic proembryo occurred spontaneously, but could also be induced by treating the developing caryopses with 2,4-Dichlorophenoxyacetic acid (2,4-D) on the second day after pollination. 2,4-D was active as a decorelative factor also evoking the expression of totipotency in individual proembryonal cells.
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    Sexual plant reproduction 5 (1992), S. 227-231 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Pollen-tube growth regulation ; In vitro pollination
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    Topics: Biology
    Notes: Summary In vitro pollen-tube growth in maize was studied using an in vitro pollination system. In the ‘cut-silk’ method, ovaries with silks were placed on medium in vitro, whereafter the silk was cut and the upper part of the silk was pollinated. Pollen tubes were not able to bridge the space between the two silk parts. Even when silk parts were tightly connected, pollen tubes still were not able to pass the cut ends and reach the lower silk part. Pollen-tube growth rates and the direction of tube growth were not influenced by the presence or absence of an ovary. Prepollination did not have any influence on pollen-tube growth rate. Measurements of pollen-tube growth rate also showed that there was no ‘population effect’, i.e. growth rate was not stimulated by pollination with an excess of pollen grains. We found that the direction in which maize pollen grew was determined only by the positioning of the silk hairs.
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    Entomologia experimentalis et applicata 54 (1990), S. 29-36 
    ISSN: 1570-7458
    Keywords: Zea mays ; corn ; host plant resistance ; phenolics ; flavonoids ; hydroxamic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réactions de larves et adultes du nitidulidé C. hemipterus (L.), vecteur de champignons produisant la mycotoxine, aux composés phénoliques caractéristiques, aux flavonoïdes et aux acides hydroxamiques, métabolites secondaires qui provoquent la résistance du maïs (Zea mays L.) ont été examinées au cours d'expériences avec et sans choix. L'alimentation des adultes et des larves est généralement réduite par les acides coumarique et férulique et par la 6-méthoxy-2-benzoxazolinone dans des expériences sans choix; les insectes évitent généralement les aliments qui contiennent ces produits. Quoi qu'il en soit, les larves préfèrent consommer d'autres aliments contenant les autres phénoliques ou flavonoïdes examinés. Les adultes sont plus inconstants dans leur choix alimentaires, mais préfèrent souvent des aliments contenant de la quercetine. Ainsi, des programmes de sélection orientés contre les principaux ravageurs comme Heliothis zea (Boddie) ou Ostrinia nubilalis (Hübner), impliquant la sélection de plantes à teneur élevée en acides phénolique ou hydroxamique, augmentant probablement aussi la résistance aux nitidulidés.
    Notes: Abstract Selected secondary metabolites produced by maize (Zea mays L.) were tested for effects on larvae and adults of the dried-fruit beetle [Carpophilus hemipterus (L.)] in no-choice and choice assays. Feeding by adults and larvae was significantly reduced by ferulic acid and 6-methoxy-2-benzoxazolinone (MBOA) in no-choice assays. In choice assays, larvae and adults generally preferred diets with trans-cinnamic acid, quercetin, rutin, and thymol, but were repelled by diets with either ferulic acid or MBOA.
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    Entomologia experimentalis et applicata 68 (1993), S. 219-229 
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Aphidiidae ; Homoptera ; Aphididae ; Schizaphis graminum ; wheat ; tritrophic interactions ; learning ; host-habitat location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of experience on the responsiveness of the aphidiid parasitoidLysiphlebus testaceipes (Cresson) (Hymenoptera: Aphidiidae) to host-associated cues was investigated using a wind-tunnel bioassay. Naive females were able to discriminate between uninfested wheat (Triticum aestivum L.) and wheat infested withSchizaphis gramimum (Rondani) (Homoptera: Aphididae), but oviposition experience significantly increased the parasitoid's propensity to respond to aphid-infested plants with upwind, targeted flight. The behavioural change associated with such experience was acquired rapidly (within five minutes) and persisted for at least 24 h. The parasitoid could be successfully conditioned to associate a novel odour with the presence of hosts, suggesting that the increase in response to aphid-infested plants which occurs as a result of experience is probably due to associative learning of olfactory cues from the plant-aphid complex.
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    Entomologia experimentalis et applicata 71 (1994), S. 177-180 
    ISSN: 1570-7458
    Keywords: aflatoxin ; Carophilus ; Zea mays ; corn ; plant resistance ; Coleoptera ; Nitidulidae
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    Entomologia experimentalis et applicata 72 (1994), S. 17-23 
    ISSN: 1570-7458
    Keywords: plant varietal resistance ; armyworm ; Spodoptera exempta ; leaf extracts ; Zea mays ; feeding deterrent ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize (Zea mays L.) leaf tissue of cv Bastille and cv Michoacan 12 was extracted with n-hexane. The extracts were bioassayed against 5th instar African armyworm,Spodoptera exempta (Walker)(Lepidoptera: Noctuidae), by feeding the larvae on agar based media or sucrose impregnated glass fibre discs. The hexane extract of the ‘resistant’ cv Bastille exhibited feeding deterrency and toxicity which were not shown by the ‘susceptible’ cv Michoacan 12. The hexane extract of cv Bastille was adsorbed onto silica gel, the solution filtered off and the adsorbed component taken up into ethyl acetate. Bioassay of these fractions indicated that the toxic and deterrent action was retained in the ethyl acetate fraction. Preparative thin layer chromatography of the ethyl acetate fraction isolated two biologically active constituents. These were both growth inhibitors and lethal by ingestion to the 5th instar African armyworm. Implications for resistance in maize varieties to insect pests are discussed.
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    Mycopathologia 111 (1990), S. 181-189 
    ISSN: 1573-0832
    Keywords: mycotoxin ; ochratoxin ; Penicillium ; storage ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Eleven-kilogram parcels of HY-320 wheat, a cultivar of the new Canada Prairie Spring class, were kept at 15 and 19% initial moisture contents (IMC) in simulated storage in a Manitoba farm granary for 60 weeks to determine biotic and abiotic changes and mycotoxin production. Ochratoxin A reached a maximum of 0.24 ppm by week 20 in the 19% IMC wheat, but was absent in the 15% IMC wheat; no other mycotoxins were detected. Temperature, moisture content, O2 and CO2 levels, fat acidity values, seed germination, microfloral incidence and abundance, and the presence of other mycotoxins were monitored. Principal component analysis of all variables showed that the first principal components accounted for 32–41% of the system variability, and contained the ochratoxin A variable. Ochratoxin A was produced in moist grain that had decreased seed germination andAltermaria activity, and high fungal activity byPenicillium andAspergillus versicolor. Compared to other stored cereals previously studied, HY-320 wheat would be ranked in a low-risk category for mycotoxin formation, based on the ochratoxin A levels observed.
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    Mycorrhiza 5 (1994), S. 119-124 
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Manganese uptake ; Root exudation ; Manganese reduction ; Mycorrhizal effect ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of rhizosphere microorganisms and vesicular-arbuscular (VA) mycorrhiza on manganese (Mn) uptake in maize (Zea mays L. cv. Tau) plants was studied in pot experiments under controlled environmental conditions. The plants were grown for 7 weeks in sterilized calcareous soil in pots having separate compartments for growth of roots and of VA mycorrhizal fungal hyphae. The soil was left either uninoculated (control) or prior to planting was inoculated with rhizosphere microorganisms only (MO-VA) or with rhizosphere microorganisms together with a VA mycorrhizal fungus [Glomus mosseae (Nicol and Gerd.) Gerdemann and Trappe] (MO+VA). Mycorrhiza treatment did not affect shoot dry weight, but root dry weight was slightly inhibited in the MO+VA and MO-VA treatments compared with the uninoculated control. Concentrations of Mn in shoots decreased in the order MO-VA〉MO+VA〉control. In the rhizosphere soil, the total microbial population was higher in mycorrhizal (MO+VA) than nonmycorrhizal (MO-VA) treatments, but the proportion of Mn-reducing microbial populations was fivefold higher in the nonmycorrhizal treatment, suggesting substantial qualitative changes in rhizosphere microbial populations upon root infection with the mycorrhizal fungi. The most important microbial group taking part in the reduction of Mn was fluorescent Pseudomonas. Mycorrhizal treatment decreased not only the number of Mn reducers but also the release of Mn-solubilizing root exudates, which were collected by percolation from maize plants cultivated in plastic tubes filled with gravel quartz sand. Compared with mycorrhizal plants, the root exudates of nonmycorrhizal plants had two fold higher capacity for reduction of Mn. Therefore, changes in both rhizosphere microbial population and root exudation are probably responsible for the lower acquisition of Mn in mycorrhizal plants.
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    Mycorrhiza 5 (1994), S. 119-124 
    ISSN: 1432-1890
    Keywords: Glomus mosseae ; Manganese uptake ; Root exudation ; Manganese reduction ; Mycorrhizal effect ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of rhizosphere microorganisms and vesicular-arbuscular (VA) mycorrhiza on manganese (Mn) uptake in maize (Zea mays L. cv. Tau) plants was studied in pot experiments under controlled environmental conditions. The plants were grown for 7 weeks in sterilized calcareous soil in pots having separate compartments for growth of roots and of VA mycorrhizal fungal hyphae. The soil was left either uninoculated (control) or prior to planting was inoculated with rhizosphere microorganisms only (MO-VA) or with rhizosphere microorganisms together with a VA mycorrhizal fungus [Glomus mosseae (Nicol and Gerd.) Gerdemann and Trappe] (MO+VA). Mycorrhiza treatment did not affect shoot dry weight, but root dry weight was slightly inhibited in the MO+VA and MO-VA treatments compared with the uninoculated control. Concentrations of Mn in shoots decreased in the order MO-VA 〉 MO+VA 〉 control. In the rhizosphere soil, the total microbial population was higher in mycorrhizal (MO+VA) than nonmycorrhizal (MO-VA) treatments, but the proportion of Mn-reducing microbial populations was fivefold higher in the nonmycorrhizal treatment, suggesting substantial qualitative changes in rhizosphere microbial populations upon root infection with the mycorrhizal fungi. The most important microbial group taking part in the reduction of Mn was fluorescent Pseudomonas. Mycorrhizal treatment decreased not only the number of Mn reducers but also the release of Mn-solubilizing root exudates, which were collected by percolation from maize plants cultivated in plastic tubes filled with gravel quartz sand. Compared with mycorrhizal plants, the root exudates of nonmycorrhizal plants had two fold higher capacity for reduction of Mn. Therefore, changes in both rhizosphere microbial population and root exudation are probably responsible for the lower acquisition of Mn in mycorrhizal plants.
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  • 47
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    Plant foods for human nutrition 42 (1992), S. 165-173 
    ISSN: 1573-9104
    Keywords: Calcium ; absorption ; wheat ; Bengal gram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheatchapati, wheat+Bengal gram (80∶20 and 70∶30)chapatis and casein diets, at 10 percent protein level, were fed to rats for 12 weeks to study the effect on calcium utilization. The supplementation of Bengal gram to wheat diets significantly improved the calcium absorption. The urinary calcium excretion in wheat+Bengal gramchapati diets was significantly less than that of wheatchapati diet fed group. The in vivo45Ca absorption (CPM/100 μl serum) was also less in wheatchapati group as compared to wheat+Bengal gramchapati diets fed groups. The supplementation of legumes to cereals improved the calcium utilization and it may be concluded that there will be no risk of occurance of protein induced hypercalciuria.
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  • 48
    ISSN: 1573-8248
    Keywords: wheat ; functional response ; predation ; prey density ; Araneae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des expériences ont été menées en laboratoire afin de déterminer sur, un plan quantitatif, le rôle, dans l'élimination des populations deRhopalosiphum padi (L.), des principales espèces d'araignées rencontrées sur blé d'hiver en Allemagne:Erigone atra (Blackwall),Lepthyphantes tenuis (Blackwall) etPardosa agrestis (Westring). Leur réponse fonctionnelle à différentes densités de proies a également été étudiée. La présence des araignées provoque une réduction importante, de 34 à 58%, de l'accroissement de la population aphidienne sur blé, par rapport à l'accroissement de cette population en l'absence d'araignées. Les courbes de réponse fonctionnelle pour ces araignées s'attaquant àR. padi semblent de type II caractéristique avec une augmentation de plus en plus faible de la consommation des proies jusqu'à ce que les densités de pucerons atteignent un plateau. Les proies tuées sans être ingérées présentent une courbe de type linéaire.
    Notes: Abstract Laboratory experiments were performed to determine the potential of dominant spider species in winter wheat in Germany,Erigone atra (Blackwall),Lepthyphantes tenuis (Blackwall) andPardosa agrestis (Westring) adults and youngs, in suppressing the population ofRhopalosiphum padi (L.) on wheat plants and their functional response to different aphid densities. The presence of spiders significantly caused between 34 and 58% reduction in aphid population development on wheat plants compared to the aphid population in the absence of spiders. The functional response curves for these spiders as predators ofR. padi seem to descrive a typical type II functional response with the prey consumed increasing to a plateau as aphid densities increased. Prey killed without eating was linear on prey density.
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  • 49
    ISSN: 1573-8248
    Keywords: Beauveria bassiana ; Ostrinia nubilalis ; endophytic relationship ; biological control ; insect pathology ; Zea mays ; Beauveria bassiana ; Ostrinia nubilalis ; lutte biologique ; relation endophyte ; pathologie de l'insecte ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le champignon entomopathogène,Beauveria bassiana (Balsamo) Vuillemin a été épandu sur maïs, au stade cornet (V7) par application foliaire d'une formulation granulée de grits de maïs contenant des conidies ou par injection d'une suspension de conidies. Toutes les plantes ont été infestées à l'aide de larves de la Pyrale du maïs,Ostrinia nubilalis, au stade V7 (cornet), V12 (fin de stade cornet), ou V17 (apparition de la panicule). Les plantes infestées au stade cornet et à la fin du stade cornet ont eu significativement plus de chenilles de Pyrale en train de miner que les plantes infestées au stade début de panicule mâle. Le pourcentage de plantes infestées parB. bassiana n'était pas significativement différent entre ces 3 stades phénologiques. Au fur et à mesure que les plantes se développaient,B. bassiana était isolé de différentes parties de la plante, la moelle étant plus souvent infestée que les ligules. Les applications foliaires deB. bassiana ont entraîné la destruction immédiate de la pyrale chez les plantes infestées au stade cornet. La baisse de l'efficacité deB. bassiana aux stades intermédiaires par comparaison avec son efficacité au moment de la récolte est discutée.
    Notes: Abstract The entomopathogenic fungus,Beauveria bassiana (Balsamo) Vuillemin, was applied to whorl-stage (V7) corn,Zea mays L., by foliar application of a granular formulation of corn grits containing conidia or by injection of a conidial suspension. All plants were infested with European corn borer larvae,Ostrinia nubilalis (Hübner), at the V7 (whorl), V12 (late-whorl), or V17 (pretassel) stage of plant development. Plants infested at whorl and late-whorl stages had significantly more European corn borer tunneling than did plants infested at the pretassel stage. The percentage of plants colonized byB. bassiana did not differ significantly among the whorl, late-whorl, and pretassel stages. As the plants matured,B. bassiana was isolated from different plant areas, with the pith more frequently colonized than the leaf collars. Foliar application ofB. bassiana provided immediate suppression ofO. nubilalis in those plants infested at whorl stage. The reduced efficacy ofB. bassiana at the intermediate plant stages relative to efficacy at harvest is discussed.
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  • 50
    ISSN: 1432-0789
    Keywords: Vigna unguiculata ; Zea mays ; Nutrient competition ; Intercropping ; Nitrate depletion ; N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha-1 year-1 as urea) and P application (0 and 60 kg P ha-1 year-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N2 fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N2 fixation was low, with the highest values in the sole cropping (53 kg ha-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N2 fixation. This was substantiated by nodule counts. The lower N2 fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N2 fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior.
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    Biology and fertility of soils 13 (1992), S. 142-146 
    ISSN: 1432-0789
    Keywords: A value ; Common bean ; N remobilization ; Soil N balance ; Atom% 15N excess ; Phaseolus vulgaris ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The common bean (Phaseolus vulgaris L.) is generally regarded as a poor N2 fixer. This study assessed the sources of N (fertilizer, soil, and fixed N), N partitioning and mobilization, and soil N balance under field conditions in an indeterminate-type climbing bean (P. vulgaris L. cv. Cipro) at the vegetative, early pod-filling, and physiological maturity stages, using the A-value approach. This involved the application of 10 and 100 kg N ha-1 of 15N-labelled ammonium sulphate to the climbing bean and a reference crop, maize (Zea mays L.). At the late pod-filling stage (75 days after planting) the climbing bean had accumulated 119 kg N ha-1, 84% being derived from fixation, 16% from soil, and only 0.2% from the 15N fertilizer. N2 fixation was generally high at all stages of plant growth, but the maximum fixation (74% of the total N2 fixed) occurred during the interval between early (55 days after planting) and late podfilling. The N2 fixed between 55 and 75 days after planting bas a major source (88%) of the N demand of the developing pod, and only about 11% was contributed from the soil. There was essentially no mobilization of N from the shoots or roots for pod development. The cultivation of common bean cultivars that maintain a high N2-fixing capacity especially during pod filling, satisfying almost all the N needs of the developing pod and thus requiring little or no mobilization of N from the shoots for pod development, may lead to a net positive soil N balance.
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  • 52
    ISSN: 1432-0789
    Keywords: Helianthus annuus ; Mycorrhiza ; Soil organic matter ; VAM response ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Vesicular-arbuscular mycorrhizal (VAM) fungi affect diverse aspects of plant form and function. Since mycorrhiza-mediated changes in host-plant responses to root colonization by different VAM fungi vary widely, it is important to assess each endophyte for each specific effect it can elicit from its host as part of the screening process for effectiveness. Three species of VAM fungi and a mixture of species were compared with non-VAM controls for their effects on soil organic matter contents and on nutrition and morphology in two varieties (native and hybrid) of corn (Zea mays L.) and one of sunflower (Helianthus annuus L.) in P-sufficient and N-deficient soil in pot cultures. Differences in soil organic matter due to the fungal applications were highly significant with all host plants. Native corn responded more to VAM colonization than the hybrid did; differences in treatments were significant in leaf area, plant biomass, and root: shoot ratio in the former, but not in the latter. Responses in the sunflower were similar to those in the native corn. Significant VAM treatment-related differences in shoot N and P contents were not reflected in shoot biomass, which was invariant. Correlations between plant or soil parameters and the intensity of VAM colonization were found only in soil organic matter with the native corn, in specific leaf area in the hybrid corn, and in plant biomass in the sunflower. The presence of the different endophytes and not the intensity of colonization apparently elicited different host responses.
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  • 53
    ISSN: 1432-0789
    Keywords: DRIS ; Helianthus annus ; Plant nutrition ; VAM ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Vesicular-arbuscular mycorrhizal (VAM) fungi improve plant growth in marginal soils. This study was conducted to determine the effects of three species of VAM fungi on plant nutrition in two cultivars of corn (Zea mays L.) and one of sunflower (Helianthus annus L.). Plants were grown in pot cultures under controlled (greenhouse) conditions in a soil high in K, Mg, and P, and low in Ca and N, and were supplied with amounts of VAM-fungal inocula in which equal numbers of infective propagules had previously been determined. Analysis of variance showed highly significant main effects and interactions due to both factors (plant and fungus) for N, P, Ca, and Mg. For K, only plant effects were significant (P〈0.043). The uptake of nutrients was selectively enhanced or inhibited by one or the other VAM fungus relative to non-VAM control plants. In sunflower, N concentration was markedly enhanced (73%) by the mixed inoculum of the three fungi, even though individual effects were not significant. Evaluation of leaf nutrient analyses by the Diagnosis and Recommendation Integrated System (DRIS) revealed the utility of this system to rank nutritional effects by VAM fungi in an order of relative nutrient deficiency. The DRIS therefore is seen as a useful tool in evaluating and selecting VAM fungi for the alleviation of specific nutrient disorders.
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  • 54
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    Plant cell, tissue and organ culture 30 (1992), S. 77-83 
    ISSN: 1573-5044
    Keywords: anther culture ; ficoll ; liquid medium ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of ficoll in liquid culture media have been contradictory in previous reports. The objective of this study was to determine the functional properties of ficoll in potato 4 (P4) liquid induction medium and their influence on anther culture responses of wheat. Ficoll addition significantly (p≤0.01) reduced callus production from the anthers of spring wheat cv. Pavon 76. The reduction was directly related to the concentration of ficoll added within the range of 50 to 200 g l-1 medium. Although the addition of ficoll significantly (p≤0.01) increased the percentage of regenerable calli and the ratio of green vs. albino plants, the final yield of green plants per 100 anthers was significantly lower. Consistent results also were obtained with four other spring wheat genotypes (Chris, Butte 86, WA 6916, and Edwall). Ficoll concentration affected the density, viscosity, and osmolality of the liquid media. The higher medium density caused by ficoll addition increased the percentage of floating calli, as well as the percentage of regenerable calli and the ratio of green vs. albino plants. However, the increased medium viscosity by ficoll addition significantly (p≤0.01) reduced callus production. Ficoll addition also increased medium osmolality, which affected callus production by interacting with the sugar concentration of the induction media. Using response functions, the estimated maltose concentration for maximum callus production was 105 g l-1 for the standard P4 media, compared with 68 g l-1 for the ficoll-containing P4 media. These results clearly demonstrate that ficoll addition to the liquid P4 induction medium containing high sucrose concentration (90 g l-1) is deleterious to the maximum production of green plants from wheat anther culture.
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  • 55
    ISSN: 1573-5044
    Keywords: cell cycle ; DNA content ; embryogenic competence ; flow cytometry ; mitotic activity ; somatic embryogenesis ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic competence of maize (Zea mays L.) leaf tissues was studied with regard to leaf age, distance from leaf base, mitotic activity, 2C nuclear DNA content, and the distribution of cells within the cell cycle. The highest embryogenic competence was observed in the first segment of the second innermost leaf. In a succession of 8 mm segments from the leaf base, the frequency of cells in the G0/G1 phase of the cell cycle and mitotic activity decreased with leaf age and with the distance from leaf base. No significant differences in 2C nuclear DNA content were found for leaf segments of different age and position. The mean 2C nuclear DNA content was 5.74 pg. The results suggested that the loss of embryogenic competence in mature maize leaf tissues is not related to changes in nuclear DNA content, and that the competence is not simply related to a certain distribution of cells within the cell cycle or to a certain level of mitotic activity.
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  • 56
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    Plant cell, tissue and organ culture 33 (1993), S. 251-257 
    ISSN: 1573-5044
    Keywords: ballistic aiming ; glucuronidase ; gold particles ; microprojectiles ; Nicotiana tabacum L. ; tobacco ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene transfer system for meristem cells was developed on the basis of a ballistic approach. In order to meet some important prerequisites for an efficient transfer system, such as for example aiming at small tissues and control of penetration of the microprojectiles, we developed an acceleration system fundamentally different from the usual macroprojectile driven approach. Instead of a macroprojectile, microtargeting uses the law of Bernoulli for accleration of highly uniform-sized gold particles. The system is able to deliver 80% of the particles to an area as small as 150 micron in diameter, which corresponds to the size of a meristem. Microtargeting yields gene delivery (measured as number of transiently GUS expressing cells to up to 3% of the cells exposed in the target area or up to 35 × 103 cells per cm2. Stable transformation of tobacco microcolonies with the microtargeting device was shown to have an efficiency up to one stable transformant per 1000 cells exposed to the shot, or up to one transformant per shot. We perform 4 or 5 shots per min. After 30 to 40 shots, reloading can take up to 2 min. Microtargeting is very flexible and allows for the adjustment of the important parameters to fit the requirements of the respective tissue.
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  • 57
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    Plant cell, tissue and organ culture 33 (1993), S. 237-246 
    ISSN: 1573-5044
    Keywords: embryogenic suspension culture ; Glycine max ; particle bombardment ; stable transformation ; transient expression ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple and inexpensive particle acceleration apparatus was designed for direct delivery of DNA to plant cells. The Particle Inflow Gun (PIG) is based on acceleration of DNA-coated tungsten particles directly in a helium steam. High levels of transient expression of theβ-glucuronidase gene were obtained following bombardment of embryogenic suspension cultures of maize and soybean, and leaf tissue of cowpea. Stable transformation of soybean and maize has also been obtained using this bombardment apparatus.
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  • 58
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    Plant cell, tissue and organ culture 24 (1991), S. 9-12 
    ISSN: 1573-5044
    Keywords: culture medium ; embryo culture ; microelements ; wheat ; zinc ; zinc deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of microelements on the induction of embryogenic callus from epiblast and scutellum of wheat (Triticum aestivum L.) embryos was studied by the sequential omission of each of the microelements from Murashige & Skoog medium. Omission of iron caused a marked decrease in yield and poor shoot formation from embryogenic callus. The yield of embryogenic callus on medium without added manganese was also reduced. Omission of boron, copper-cobalt, iodine, and molybdenum had little effect on the induction of embryogenic epiblast callus. By contrast there was a marked increase in the formation of white structures on the medium without any microelements or, specifically without addition of zinc. Since the formation of typical embryoids of wheat is associated with the formation of white structures, our result highlights the importance of certain microelements on somatic embryogenesis of wheat.
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    Plant cell, tissue and organ culture 24 (1991), S. 233-236 
    ISSN: 1573-5044
    Keywords: anther culture ; cultivars ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty-two cultivars and lines of winter and spring wheat (Triticum aestivum L.) were studied, most for the first time, for their anther culture response. The response was genotype dependent. Plants grown in the field gave higher callus induction frequency than those grown in the greenhouse and the controlled environment chamber. Donor plants grown in a season of low drought stress as compared to a season of severe drought stress resulted in a higher frequency of callus induction. Spherical microcalli were observed in two wheat genotypes in some of only those anthers that were placed with only one loculus in contact with the medium. Wheat lines that were more responsive to anther culture were identified.
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  • 60
    ISSN: 1573-8248
    Keywords: Coccinella septempunctata ; distribution verticale ; comportement ; alimentation ; puceron ; blé ; Coccinella septempunctata ; vertical distribution ; behaviour ; feeding ; aphid ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Observations were made in a wheat field during daylight hours to determine how the vertical distribution of adults and larvae ofCoccinella septempunctata changed with season and in response to aphid populations on which this coccinellid feeds. In early spring, this thermophilic coccinellid (larvae and adults) remained close to the ground and on the lower part of tiller leaves where it was highly active. Adults frequently groomed their head appendages. By June, most adults and larvae were found on the upper parts of tillers, the area preferred by their aphid prey. The beetles remained close to such sites and hence their vertical distribution corresponded to that of the aphids on which they fed. The fact that the beetles appeared to spend most of their time resting and moving within wheat crops, and little time feeding, raises the question of how the larvae and adults satisfy their dietary needs.
    Notes: Abstract Des adultes et des larves deC. septempunctata ont été observés individuellement dans un champ de blé afin de préciser, au cours de la journée et en fonction de la saison, leur distribution sur le végétal, la durée des principales séquences de leur comportement et leurs relations avec les pucerons. Au début du printemps, cette espèce thermophile est présente sur le sol et sur les feuilles basses des talles où elle est très mobile. Les adultes font très fréquemment la toilette des appendices de la tête. En juin, la population larvaire et imaginale se regroupe sur la partie supérieure des talles où se trouvent les pucerons. A cette époque, l'immobilité domine. Ces variations de la distribution verticale sont confirmées par la position sur le végétal des proies capturées. Les données suggèrent que, dans les champs, cette coccinelle consacre peu de temps à son alimentation. Le faible nombre de proies ingérées pose le problème de la couverture de ses besoins trophiques.
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  • 61
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    Plant cell, tissue and organ culture 33 (1993), S. 45-50 
    ISSN: 1573-5044
    Keywords: androgenetic structure quality ; anther culture ; plant regeneration ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six media compositions and different transfer times were compared in order to improve the quality of microspore derived structures and their regeneration capacity. The production of regenerated plantlets was increased by a factor of 10 by an early transfer of anthers to medium with low sugar concentration and the use of kinetin-like growth regulators. The best transfer date was 3 weeks after initial plating, onto medium containing 25 gl−1 sucrose and 1 mg l−1 kinetin. This study demonstrates that anther transfer at an early developmental stage, before macroscopic appearance of embryo-like structures, improves embryo quality and further regeneration. This production of androgenetic structures showing normal morphological features is the first step to obtain an improvement of androgenetic plant regeneration yield.
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  • 62
    ISSN: 1573-5044
    Keywords: DNA delivery ; electroporation electrolyte ; heat shock ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electroporation was used for the delivery and subsequent expression of GUS and anthocyanin reporter genes into intact maize immature embryos. The optimal conditions consisted of culturing immature embryos for 4 days on N6 1-100-25-Ag medium prior to electroporation (375 V/cm; 960 µF capacitance) in EPR buffer containing DNA and 0.07 M sodium glutamate at room temperature (22°C) after a 10 min heat shock at 37°C. Under these conditions, over 40 spots of GUS transient activity were observed per immature embryo. Transient gene expression after electroporation was further demonstrated using an anthocyanin construct, which is specific for expression in plant cells.
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  • 63
    ISSN: 1573-8469
    Keywords: wheat ; Triticum aestivum ; oat ; Avena sativa ; barley ; Hordeum vulgare ; serology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Various modifications of the tissue-blot immunoassay (TBIA) for the detection of barley yellow dwarf virus (BYDV, luteovirus) were compared. Similar results were obtained by using three different labelled molecules; goat anti-rabbit antibodies conjugated to alkaline phosphatase, protein A conjugated with alkaline phosphatase and goat anti-rabbit antibodies conjugated with colloidal gold. Blocking the nitrocellulose membrane with polyvinyl alcohol for 1 min was effective and allowed the procedure to be shortened by one hour. TBIA was sensitive enough to detect BYDV in old dry tissue wich had been soaked in water for 1 h. BYDV was monitored by TBIA in wheat, oat and barley after inoculation at heading, flowering and grain filling growth stages. The later the inoculation date, the greater the chance of detecting the virus in stem bases rather than in the upper part of the stem. The later the inoculation the less virus moved, from the inoculated tiller to other tillers of the same plant.
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  • 64
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    European journal of plant pathology 96 (1990), S. 187-198 
    ISSN: 1573-8469
    Keywords: fusarium head blight ; Fusarium culmorum ; F. graminearum ; wheat ; mycotoxin ; deoxynivalenol ; nivalenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Aaraantasting van tarwe doorFusarium culmorum enFusarium graminearum leidt tot vorming van mycotoxinen in het graan, waarvan deoxynivalenol (DON) en nivalenol (NIV) de belangrijkste toxinen zijn. In dit artikel wordt een overzicht gegeven van de toxicologische aspecten, en het voorkomen van deze toxinen in tarwe. Informatie over DON en NIV in tarwe in West-Europa is schaars. Gebaseerd op gegevens vanFusarium epidemieën in de jaren 1979–1986 wordt een schatting gegeven van de concentratie DON in Nederlandse tarwe. Rekening houdend met de herkomst en verwerking van tarwe, blijken zowel in dierlijk als menselijk voedsel lage concentraties DON chronisch voor te komen. Op basis van een maximaal toelaatbare dagelijkse dosis DON van 3 μg kg−1 lichaamsgewicht is de schatting van de dagelijkse opname van DON in het jaar volgend op de oogst van 1982 net op de grens. Zowel een jaarlijkse inventarisatie vanFusarium aantasting en DON besmetting van het graan, als de ontwikkeling vanFusarium-resistente rassen zijn noodzakelijk.
    Notes: Summary An infection of bread wheat by fusarium head blight contaminates the crop with mycotoxins, particularly deoxynivalenol (DON) and nivalenol (NIV). The toxicity and natural occurrence of these mycotoxins in wheat are reviewed. Based on 8 years data of fusarium head blight epidemics of wheat in the Netherlands, DON contamination of the grain was estimated. Fusarium head blight ratings averaged an infection of 1.7% of all spikelets; estimates for DON contamination averaged 0.9 mg kg−1. Taking a guideline level for DON in uncleaned bread wheat of 2 mg kg−1, in 1979 and 1982 a wheat crop was produced with estimated DON concentrations above the limit of tolerance. Human and animal exposure to mycotoxins in the Netherlands appears to be small but chronic. The information presented in this paper illustrates the need for an annual evaluation of the crop for fusarium head blight incidence and mycotoxin content, and the necessity of fusarium head blight resistant wheat cultivars.
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    European journal of plant pathology 97 (1991), S. 65-72 
    ISSN: 1573-8469
    Keywords: speckled leaf blotch ; wheat ; growth type ; pseudopycnidia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The in vitro production of pycnidia bySeptoria tritici was examined on six media reported to induce the formation of fruiting bodies. Among 26 freshly isolated cultures from various parts of the world, consistent differences in growth type were found which were only partially influenced by nutritional and environmental conditions. Cultures with yeast-like growth produced hardly any pycnidia or pseudopycnidia, while cultures with intermediate or mycelial growth types produced them frequently. Incubation in continuous darkness induced intermediate to mycelial growth types rather than yeast-like growth types in some cultures, and concomitantly the production of more pycnidia. Potato-dextrose agar induced intermediate to mycelial growth types and production of (pseudo)pycnidia more often than V8 agar and wheat leaf extract agar, which had previously been reported to be especially beneficial to (pseudo) pycnidium formation byS. tritici. Isolates with a consistently yeast-like growth type, producing (virtually) no fructifications under any of the experimental conditions, were slightly stimulated to form pseudopycnidia on water agar supplemented with sterile pieces of maize, wheat or carnation leaves.
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  • 66
    ISSN: 1617-4623
    Keywords: Transcriptional activators ; O2 gene ; Zea mays ; bZIP proteins ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of this research was to determine whether the structural homology between the O2 gene, a maize transcriptional activator, and the GCN4 gene, a yeast transcriptional factor, is reflected at the level of function. The O2 cDNA was cloned in the yeast expression vector pEMBLyex4 under the control of a hybrid, inducible promoter, and used to transform the yeast Saccharomyces cerevisiae. Transformed yeast cells produced O2 mRNA and a polypeptide immunoreactive with anti-O2 antibodies during growth in galactose. The heterologous protein was correctly translocated into the yeast nuclei, as demonstrated by immunofluorescence, indicating that the nuclear targeting sequences of maize are recognized by yeast cells. Further experiments demonstrated the ability of O2 to rescue a gcn4 mutant grown in the presence of aminotriazole, an inhibitor of the HIS3 gene product, suggesting that O2 activates the HIS3 gene, gene normally under control of GCN4. It was shown that the O2 protein is able to trans-activate the HIS4 promoter in yeast cells and binds to it in vitro. The sequence protected by O2, TGACTC, is also the binding site for GCN4. Finally, the expression of O2 protein in yeast did not produce alterations during batch growth at 30° C, while transformants expressing O2 protein showed a conditionally lethal phenotype when grown in galactose at 36° C; this phenotype mimics the behaviour of gcd mutants. The results support the idea that basic mechanisms of transcription control have been highly conserved in eukaryotes.
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  • 67
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    Molecular genetics and genomics 242 (1994), S. 1-8 
    ISSN: 1617-4623
    Keywords: Zea mays ; Flavonoid biosynthesis ; P gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the first cloning of a chalcone flavonone isomerase gene (CHI) from maize. Northern blot experiments indicate that the maize CHI gene (ZmCHI1) is regulated in the pericarp by the P gene, a myb homologue. The ZmCHI1 gene encodes a 24.3 kDa product 55% and 58% identical to CHI-A and CHI-B from Petunia, respectively. This maize CHI gene has four exons and an intron-exon structure identical to the CHI-B gene of Petunia hybrida. RFLP mapping data indicate that some inbred lines contain two additional CHI-homologous sequences, suggesting an organization more complex than that found in Petunia or bean. The possibility that the additional CHI-homologous sequences are responsible for the lack of CHI mutants in maize will be discussed.
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  • 68
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    Agroforestry systems 17 (1992), S. 43-51 
    ISSN: 1572-9680
    Keywords: agroforestry ; Acacia nilotica var. jaquemontii ; wheat ; bund plantation ; crop yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The paper presents the results of a case study conducted to find out the influence of single row bund plantation of Acacia nilotica var. juquemontii on the growth and yield of associated wheat crop under irrigated conditions in Haryana, India. The indications are that the tree line does affect all crop parameters like height growth, shoot numbers, ear length, grain number and grain yield in the vicinity of trees upto 4 m distance from the tree line and establishes that as the distance from the tree line increases the growth and yield of wheat crop also improves. The effect on wheat crop was found more pronounced in the plots laid out towards the middle of the tree line as compared to plots towards the outer border.
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  • 69
    ISSN: 1572-9680
    Keywords: Cicer arietinum ; Eragrostis tef ; Pisum sativum ; tropical tree plantations ; Zea mays
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential allelopathic effect ofCupressus lusitanica, Eucalyptus globulus, E. camaldulensis andE. saligna on seed germination, radicle and seedling growth was investigated with four crops:Cicer arietinum (chickpea),Zea mays (maize),Pisum sativum (pea) andEragrostis tef (teff). Aqueous leaf extracts of all the tree species significantly reduced both germination and radicle growth of the majority of the crops mostly starting from concentrations of 1% or 2.5%. The shoot and root dry weight increase of the crops was significantly reduced after 10 weeks treatment with leaf extracts. Among the four crops, chickpea and teff were most susceptible with respect to germination, and teff with respect to growth. From the overall data the leaf extracts of the four tree species can be arranged according to increasing allelopathic potential:C. lusitanica, E. globulus, E. saligna andE. camaldulensis. It is suggested that the planting ofE. camaldulensis andE. saligna in integrated land use systems should be minimized, whereas the use ofC. lusitanica andE. globulus seems less environmentally damaging in this respect.
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    Agroforestry systems 25 (1994), S. 23-29 
    ISSN: 1572-9680
    Keywords: Acacia nilotica ; wheat ; border trees ; crop yield ; Pakistan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Planting trees in the cultivated fields of Pakistan is a controversial topic between foresters and agriculturists. Some farmers believe that trees significantly reduce their crop yields; therefore they avoid planting trees in their fields. On the other hand, many foresters claim trees are beneficial for crops. This study was conducted to determine the influence of boundary trees (Acacia nilotica) on the growth and yield of associated wheat crops under irrigated conditions in Punjab, Pakistan. Results indicate that close proximity to trees adversely affected tillers/m2, weight/1000 grain and the grain yield of wheat planted up to a distance of 8.5 m from the trees. Plant height and grains/spike were least affected. In general, the growth and yield of wheat improved as distance from the tree increased. Tree size did not affect wheat height, tillers/m2, grains/spike or weight/1000 grain. The grain yields were slightly lower near the largest trees (50–54.9 cm DBH trees).
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  • 71
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    Agroforestry systems 19 (1992), S. 217-222 
    ISSN: 1572-9680
    Keywords: poplar ; wheat ; yield reduction ; GBH ; agrisilviculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In an agrisilvicultural system having poplar (Populus deltoides, clone G-3) as a tree component and wheat crop as an intercrop, wheat yield was studied under five age classes of poplar and compared to wheat yield under pure cropping. A substantial reduction in wheat yield (23.3%) under three-year-old poplar plantation was observed. Maximum MAI (GBH, 20 cm) was recorded in a three-year-old poplar planting. Pruning after the third year permitted some recovery in yield. The reduction in wheat yield was significantly correlated with MAI (GBH) of poplar and occurred even under one-and-two-year-old poplar plantings.
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  • 72
    ISSN: 1572-9680
    Keywords: Gliricidia sepium ; Zea mays ; alley cropping ; intercropping ; Sierra Leone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of spacings between hedgerows (alley widths) and the spacings of trees within hedgerows ofGliricidia sepium on growth and grain yield of maize were investigated at Senehun in southern Sierra Leone. Four between-row spacings (2, 4, 6 and 8 m) were combined with three within-row spacings (0.25, 0.50 and 1.00 m) in a split block design. Maize, at densities of 20,000, 40,000 and 53,333 plants ha−1, was established in the alleys and also as pure crops. N, P and K fertilizers were applied to all plots before pruning of the trees began. When pruning started, only the pure maize plots received fertilizer; prunings from the hedgerows were returned to the appropriate alleys in the other plots. Plots with the highest maize populations consistently gave the best yields before pruning started, but lower populations gave improved yields after pruning. Yields of maize increased with increasing alley widths before the start of pruning, after which the narrower alleys of 2 and 4 m outyielded the wider ones by almost double, probably because of the large amount of nutrients applied in prunings. Lack of light limited grain yields before the start of pruning, when there was some shading by the hedgerows. Alleys of 2–4 m wide, planted no closer than 0.50 m within rows, resulted in more than twice the yields of maize than in the 8-m alleys planted at 0.25 m within rows, once the hedgerows were well established and were being managed.
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  • 73
    ISSN: 1573-1561
    Keywords: Allelochemicals ; no-tillage ; conventional-tillage ; soils ; wheat ; Triticum aestivum ; mass spectrometry ; Petri-dish bioassay ; fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Putative allelochemicals found in the soil of no-tillage and conventional-tillage wheat plots near Stillwater, Oklahoma, were obtained by a mild alkaline aqueous extraction procedure, bioassayed to determine their biological activity, purified, and analyzed with a capillary gas chromatography-mass spectrometry-data analysis system. The most significant inhibition was found in bioassays of extracts from soil collected immediately after harvest in June, July, and August. No-tillage soils produced significant inhibition during the rest of the year also. Mass spectrometry showed fatty acids as the most abundant compounds. However, when bioassayed authentic samples of the five free fatty acids showed no significant biological activity toward wheat.
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  • 74
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    Journal of chemical ecology 20 (1994), S. 3335-3344 
    ISSN: 1573-1561
    Keywords: Diabrotica virgifera virgifera ; fatty acids ; linoleic acid ; oleic acid ; stearic acid ; semiochemical ; attractants ; western corn rootworm ; host location ; Coleoptera ; Chrysomelidae ; Zea mays ; kairomone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A bioassay-driven sequential fractionation scheme was used to isolate fractions of a crude dichloromethane maize seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. (Z,Z)-9,12-Octadecadienoic (linoleic) acid, (Z)-9-octadecenoic (oleic) acid, and octadecanoic (stearic) acid were identified from a purified fraction of maize extract that was attractive to western corn rootworm larvae in choice tests with equal levels of carbon dioxide on both sides of the choice. When synthetic linoleic, oleic, and stearic acids were tested together in the amounts and proportions found in the attractive fraction (1000, 800, and 300 ng of linoleic, oleic, and stearic acids, respectively), significantly more western corn rootworm larvae were found on the side with synthetic free fatty acids plus carbon dioxide than on the side with carbon dioxide alone. Results of the choice-test bioassays were not significantly different when the synthetic blend of free fatty acids was substituted for the purified maize fraction. Neither the purified extract nor the synthetic blend was behaviorally active in preliminary single-choice experiments without carbon dioxide. Linoleic, oleic, and stearic acids were also tested individually in the choice test bioassay with carbon dioxide on both sides of the choice to determine a dose-response curve. Linoleic and oleic acid each had one dose that was significantly attractive in conjunction with carbon dioxide on both sides of the choice, but stearic acid was not active in the doses tested.
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    Journal of chemical ecology 18 (1992), S. 931-944 
    ISSN: 1573-1561
    Keywords: Diabrotica virgifera virgifera ; 6-methoxy-2-benzoxazolinone ; hydroxamic acids ; semiochemical ; attractants ; western corn rootworm ; host location ; Coleoptera ; Chrysomelidae ; Zea mays ; kairomone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A bioassay-driven sequential fractionation scheme was used to isolate all portions of a crude dichloromethane corn seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. 6-Methoxy-2-benzoxazolinone (MBOA) was identified as one of the most important components of an attractive crude corn extract. MBOA was found on or in the intact root tissues by injecting an extract of undamaged roots onto an HPLC immediately after extraction. MBOA was demonstrated to be volatile and functions as a semiochemical in conjunction with carbon dioxide in host location by western corn rootworm larvae, which are oligophagous on the roots of maize and several other species of grasses. Because MBOA occurs almost exclusively in maize and other grasses, it offers a simple way for the larvae to distinguish possible hosts from non-hosts. MBOA has previously been reported as a chemical defense against other insect species. This is the first report in grasses of a secondary compound that is toxic or a deterrent to nonadapted insect herbivores but that is used as a semiochemical in host location by a specialist insect species.
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  • 76
    ISSN: 1573-1561
    Keywords: Hydroxamic acids ; phloem sap analysis ; aphid resistance ; cereals ; wheat ; Rhopalosiphum padi ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phloem sap of wheat seedlings differing in whole leaf hydroxamic acid (Hx) concentrations was collected by cutting stylets of feeding aphids. DIMBOA-glucoside was the only Hx-related product found. Concentration of DIMBOA-glucoside in phloem sap showed a tendency to be negatively correlated with aphid performance.
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    Journal of chemical ecology 19 (1993), S. 1613-1624 
    ISSN: 1573-1561
    Keywords: Zea mays ; corn ; cyclic hydroxamic acids ; DIMBOA ; DIBOA ; water stress ; drought ; osmotic priming ; insect resistance ; disease resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cyclic hydroxamic acids are innate compounds associated with pest resistance in several grass species. The major cyclic hydroxamic acids of com, 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-one (DIMBOA) and 2,4-dihydroxy-3H-1,4-benzoxazin-3-one (DIBOA), were measured in seedlings after exposure to various water stress treatments. Both DIMBOA and DIBOA were found in greater quantities in plants experiencing a water deficit stress than in nonstressed plants. The increased cyclic hydroxamic acid coincided with a reduction in seedling growth, suggesting that cyclic hydroxamic acids are stress metabolites. Plants grown under conditions that restrict growth, such as water deficit stress, contain higher cyclic hydroxamic acids, which should make them more resistant to herbivorous pests and pathogenic microorganisms.
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  • 78
    ISSN: 1573-1561
    Keywords: Fall armyworm ; Spodoptera frugiperda ; Lepidoptera ; Noctuidae ; corn ; Zea mays ; plant-insect interaction ; amino acids ; herbivory ; feeding resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The free amino acids have been shown by isolational work and choice bioassays to be more important than all other factors evaluated in defining leaf-feeding resistance of corn (Zea mays L.) to fall armyworm (FAW) [(Spodoptera frugiperda J.E. Smith)] larvae. 6-MBOA (6-methoxybenzoxazolinone) and maysin, toxins present in corn, were shown not to be significant factors for leaf-feeding resistance to first-instar FAW larvae because of their low concentrations in the whorl. Amino acid analysis showed that while the ratios of the essential amino acids in susceptible (S) and resistant (R) lines were similar, there were differences in the nonessential amino acids, particularly aspartic acid, which was higher in R lines. Also, the ratio of essential amino acids to nonessential amino acids was important, being too low in expressed whorl leaf juice (obtained from V8–V10 growth stage plants) to support larval growth, although juice was stimulatory in choice tests. The total protein content of whorls in S lines was about 15% higher than in R lines, but the significance of this difference is uncertain, because nutritional tests showed that larval growth increased with total protein only up to 12% protein. Sugars were only slightly stimulatory. Thus, the amino acids along with higher hemicellulose content of R lines, established by us earlier, appear to explain much of the basis of resistance in corn to larval leaf-feeding of the FAW.
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  • 79
    ISSN: 1573-1561
    Keywords: Hessian fly ; Mayetiola destructor ; Diptera ; Cecidomyiidae ; oviposition stimulants ; wheat ; rye ; barley ; oat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract More than twice the number of mated female Hessian flies,Mayetiola destructor (Say) entered a zone within 1 cm of a paper strip treated with one plant equivalent (PE) of a chloroform extract of wheat foliar waxes compared to a strip treated with solvent only; females also stayed six times longer and laid 10 times more eggs on the strip treated with the wheat extract. Column chromatographic fractionation of the wheat extract and application of these fractions onto filter paper strips showed four fractions elicited significant numbers of eggs to be laid. Single, binary, and tertiary combinations of three of these fractions (two of the four fractions apparently contained similar compounds) were tested. The greatest numbers of eggs were laid on strips treated with the tertiary combination or the binary combination conaining the two most active fractions (3 and 6); three times the number of eggs were laid on strips treated with this binary combination than the sum of eggs laid on strips treated with these two fractions separately. A comparison of grasses and their extracts showed female Hessian flies laid greater numbers of eggs on wheat or rye than on barley or oat. Fractionated barley and oat extracts were tested for activity as for wheat, and a similar pattern was observed, i.e., the greatest numbers of eggs were laid on fractions 3 and 6. Dose-response tests, using these two fractions of wheat, barley, or oat showed the same threshold of activity for fraction 3 for all three extracts, i.e., 2 PE. In contrast, fraction 6 of wheat was active at the lowest dosage tested, 0.25 PE, while the same fraction of either barley or oat was not active until tested at a dosage of 2 PE. It appears that (at least) two chemicals in the foliar waxes of these grasses influence ovipositional behavior of female Hessian flies. Furthermore, given the similar foliar chemistry of these grasses and the strong synergistic interaction between fractions 3 and 6 shown for wheat extract, it is likely that the ovipositional preferences exhibited by female Hessian flies towards these grasses may be explained by quantitative differences in the amount(s) of the active chemical(s) in their respective fraction 6 (most polar fraction tested).
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    Journal of chemical ecology 18 (1992), S. 1227-1237 
    ISSN: 1573-1561
    Keywords: Western corn rootworm ; Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; bacteria ; carbon dioxide ; pheromone ; semiochemicals ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract FemaleDiabrotica virgifera virgifera LeConte were allowed to choose between oviposition substrates that were and those that were not associated with potential sources of semiochemicals. Females deposited over five times more eggs on moist towelettes that were treated with homogenates of female abdomens than on towelettes treated with distilled water. Similar results were obtained when screening separated the homogenates from the towelettes, indicating that odors alone could elicit the response. In contrast, females did not choose towelettes that had previously been used for oviposition or towelettes containing eggs over unused towelettes. Further tests with homogenates of abdomens and a bacteriostatic agent (sorbate) indicated that the females were probably responding to bacterial odors rather than an oviposition-enhancing pheromone. Four strains of bacteria were isolated from a homogenate of female abdomens; females deposited 4 to 16 times more eggs on substrates with odors of the bacteria than on substrates with odors of uninoculated nutrient agar. In no-choice tests, bacterial odors did not increase the number of eggs deposited per female beetle; however, in choice tests with dishes that tended to retain any beetles that entered, there were more eggs per female (but not more beetles) after 24 hr in dishes with bacterial odors than in those without the odors. Females also chose dishes with odors of excised maize (Zea mays L.) roots or elevated levels of carbon dioxide over “control” dishes.
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    Journal of chemical ecology 16 (1990), S. 3425-3439 
    ISSN: 1573-1561
    Keywords: Coleoptera ; Chrysomelidae ; Diabrotica virgifera virgifera ; semiochemical ; kairomone ; attractants ; repellents ; Zea mays ; western corn rootworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Dichloromethane extracts of germinating corn are significantly attractive to western corn rootworm larvae in choice tests with equal levels of carbon dioxide present on both sides of the choice. Two fractions that are significantly attractive and two fractions that are significantly repellent to larvae were isolated from these extracts of germinating corn by gas chromatography and silica gel chromatography. In a separate set of experiments, Porapak N was used to collect headspace volatiles from germinating corn; significantly more larvae were attracted to aliquots of these extracts in singlechoice tests without added carbon dioxide present than to solvent controls.
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  • 82
    ISSN: 1573-1561
    Keywords: Cover crops ; wheat ; Triticum aestivum ; soybean ; Glycine max ; soil extracts ; germination bioassays ; phenolic acids ; hydroxamic acids ; allelopathy ; slope analysis ; ivy-leaved morning glory ; Ipomoea hederacea ; crimson clover ; Trifolium incarnalum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soils
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  • 83
    ISSN: 1573-1561
    Keywords: Elicitor ; corn ; Zea mays ; caterpillar regurgitate ; plant volatiles ; synomones ; semiochemicals ; parasitoids ; Cotesia marginiventris ; Microplitis croceipes ; host searching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Regurgitate of corn-fed beet armyworm (BAW) caterpillars,Spodoptera exigua, when applied to damaged sites of corn (Zea mays) seedlings, causes the release of relatively large amounts of terpenes by the seedlings several hours later. This plant response could be induced by merely placing the cut stem of seedlings in a solution of BAW regurgitate for 12 hr, a response that could not be induced by placing seedlings in water only. Regurgitate of BAW fed various diets, including a minimal diet of filter paper, were all active. However, seedlings placed in corn leaf juice, BAW hemolymph, or BAW feces extract released significantly smaller amounts of terpenes than did seedlings placed in BAW regurgitate. These results indicate that the active components are present in relatively large concentrations in regurgitate and that they are not related to the food source. Furthermore, regurgitate from several other species of caterpillars (Spodoptera frugiperda, Helicoverpa zea,Trichoplusia ni, andAnticarsia gemmatalis) as well as from the grasshopperSchistocerca americana induced the release of significant amounts of terpenes in corn seedlings. The release of these volatiles, therefore, appears to be a general response to attack by phytophagous insects. The terpene-releasing corn seedlings were highly attractive to the generalist parasitoidCotesia marginiventris and to the specialized parasitoidMicroplitis croceipes. This study confirms a systemic herbivore-elicited release of terpenes in corn. It is proposed that such chemicals serve multifunctional purposes that directly and indirectly protect plants against herbivorous arthropods and pathogens.
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  • 84
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    Journal of chemical ecology 18 (1992), S. 841-846 
    ISSN: 1573-1561
    Keywords: Rhopalosiphum padi ; Homoptera ; Aphididae ; wheat ; maize ; DIMBOA ; hydroxamic acids ; aphid honeydew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract DIMBOA glucoside (2-O-/gb-D-glucopyranosyl-4-hydroxy-7-meth-oxy-1,4-benzoxazin-3-one), the main hydroxamic acid (Hx) in intact wheat plants, was detected in the honey dew ofRhopalosiphum padi feeding on seedlings of six wheat cultivars that differed in their concentration of Hx, suggesting that the chemical circulates in the phloem. Neither the aglucone (DIMBOA) nor its main breakdown product were found in any of the honeydew samples. Honey dew production by aphids caged on seedlings of the wheat cultivars and DIMBOA glucoside concentrations in the honeydew followed biphasic curves when plotted against Hx concentration, suggesting passive ingestion of the chemical from the phloem at low Hx concentrations and limited ingestion due to feeding deterrency by Hx in mesophyll cells at high Hx concentrations. The presence of plant toxins such as Hx glucosides in the phloem sap, the main ingesta of aphids, and in the mesophyll cells, has major implications for plant defense, through a feeding deterrent effect during stylet penetration, and deterrency (antixenosis) along with antibiosis during feeding.
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  • 85
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    Journal of chemical ecology 18 (1992), S. 897-905 
    ISSN: 1573-1561
    Keywords: Pollen ; corn ; Zea mays ; teosinte ; Zea mexicana ; allelopathy ; phenylacetic acid ; phytotoxicity ; Amaranthus leucocarpus ; Echinochloa crusgalli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phenylacetic acid (PAA), one of the phytotoxic compounds in corn (Zea mays) pollen, was identified by GC-MS and by direct comparison with a pure commercial sample of PAA. Bioassays were carried out by testing whole pollen, methylene chloride extract of the pollen, and pure PAA on germination and radical growth ofAmaranthus leucocarpus andEchinochloa crusgalli. The effect of corn pollen was compared with that ofZea mexicana (Teosinte), one of the wild relatives of cultivated maize.
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  • 86
    ISSN: 1573-1561
    Keywords: Spodoptera frugiperda ; Lepidoptera ; Noctuidae ; Zea mays ; scanning electron microscopy ; cuticular lipids ; host-plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The cuticular lipid composition of lower and upper leaves of five genotypes of field-grown corn,Zea mays L., was determined by combined gas chromatography-mass spectrometry. Surface lipids of the upper leaves had a higher proportion ofn-alkanes (45–52%) than the lower leaves, while the lower leaves had higher percentages of fatty alcohols (12–18%) than the upper leaves. Scanning electron microscopy showed that the upper leaves of two corn genotypes, MpSWCB-4 and Cacahuacintle X's, had a smooth amorphous appearance, while the lower leaves had a dense array of wax crystals.Spodoptera frugiperda (J.E. Smith) larvae weighed more and developed more rapidly when they were reared on diet containing corn foliage from which the cuticular lipids had been removed than when they were fed untreated foliage. However, growth was not inhibited when larvae were fed diet containing the cuticular lipid extracts or individual cuticular lipid components.
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  • 87
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    Journal of chemical ecology 18 (1992), S. 1981-1990 
    ISSN: 1573-1561
    Keywords: Allelopathy ; ferulic acid ; amylase ; maltase ; invertase ; acid protease ; acid phosphatase ; Zea mays ; growth ; root ; shoot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ferulic acid was tested for its effect on the growth of root and shoot, fresh and dry weights, and hydrolytic enzyme activities of germinating maize seeds. The results showed that root growth was inhibited more than shoot growth. A significant reduction in the activities of hydrolytic enzymes was also observed, which reflects a mechanism of action for the natural growth inhibitors, which may include other phenolic compounds.
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  • 88
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    Journal of chemical ecology 19 (1993), S. 2453-2461 
    ISSN: 1573-1561
    Keywords: DIMBOA ; MBOA ; DIM2BOA ; M2BOA ; 2-amino-7-methoxy-3H-phenoxazin-3-one ; 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one ; corn ; wheat ; soil microbial transformation ; phytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The defensive cyclic hydroxamates 7-methoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIMBOA) and 7,8-dimethoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIM2BOA) of wheat and corn are transformed in nonsterile soil, via 6-methoxy-2(3H)-benzoxazolone (MBOA) and 6,7-dimethoxy-2(3H)-benzoxazolone (M2BOA) respectively, into 2-amino-7-methoxy-3H-phenoxazin-3-one and 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one. The soil transformation is similar of that undergone by the rye metabolite 2(3H)-benzoxazolone (BOA) into 2-amino-3H-phenoxazin-3-one. The transformations to phenoxazinones are not observed in sterile soil. The 2-amino-3H-phenoxazin-3-one inhibits barnyard grass radicle elongation, but the methoxylated aminophenoxazinones are not significantly inhibitory.
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  • 89
    ISSN: 1573-0867
    Keywords: Grain protein content ; nitrogen harvest index ; nitrogen supply ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to determine the effect of N availability upon N uptake and nitrogen partitioning efficiency and its relationship with %N in the grain in two wheat cultivars, differing in their grain protein content. Plants were grown in a nutrient solution with 2 nitrogen levels, 200 ppm (H) and 40 ppm (L). Four treatments were imposed: HH, HL, LH and LL. Nutrient solution exchange was done at maximum floret number. Plants were harvested at terminal spikelet stage, maximum floret number, 10 days after anthesis and maturity. Nitrogen content, N uptake and N distribution at maturity were significantly affected by N supply. Nitrogen content in the grain was similar in both cultivars, but varied significantly between treatments and decreased as follows: LH; HH; LL and HL. In both cultivars a low leaf %N was observed in HL 10 days after anthesis, which suggest early N utilization and its premature depletion, resulting in a low %N in the grain. Total %N in the plant, for both cultivars was higher in HH and LH than other treatments. When N availability was high during the whole crop cycle (HH), N distribution to the ear was improved. It is concluded that late N availability is necessary to achieve high %N in the grain. On the other hand if high and initial N availability is not maintained, %N in the grain decreased in a significant way.
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  • 90
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    Nutrient cycling in agroecosystems 22 (1990), S. 147-159 
    ISSN: 1573-0867
    Keywords: Sulfate ; elemental sulfur ; leaching ; ryegrass ; wheat ; greenhouse experiments ; split application
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three factorial experiments with four replications were conducted in a greenhouse to examine the effectiveness of gypsum, elemental sulfur (ES powder) and three S containing N fertilizers, viz., ammonium sulfate (AS), urea + ES, and Ureas (20% AS and 80% urea). All experiments were conducted twice in different years. In the first experiment with uncropped soil, the effects of soil type, leaching rate (2.3 and 6.9 mm water per day) and urea addition on sulfate leaching losses were studied. Leaching losses decreased in the order Ureas 〉 ammonium sulfate (AS) 〉 gypsum ≫ urea + ES. Increasing the leaching rate greatly increased sulfate losses from both soils. Losses were greater in the sandy Typic Hapludoll than in the clayey Oxic Paleustalf. Sulfate adsorption was found to decrease strongly with rising the pH in both soils. Hydrolysis of urea temporarily raised the pH of the soil, thereby increasing the sulfate leaching losses. In the second experiment the effects of S rate (0–65 mg per kg soil), split application and leaching rate (0 and 2.3 mm per day) on sulfate leaching losses and ‘apparent S recovery’ (ASR) by three successive cuts of ryegrass (Lolium perenne L.) were studied. Herbage yield more than doubled when S was applied. The effectiveness of the sulfate fertilizers was greater when S was split-applied than given all at once. With split applications the ASR decreased in the order: Ureas 〉 AS 〉 gypsum 〉 urea + ES 〉 ES powder. ES fertilizers were least effective, because the oxidation rate of ES to sulfate was clearly too slow. In the third experiment the effects of S rate (0–40 mg per kg soil) and split application on sulfate leaching losses and ASR in the grain of wheat (Triticum aestivum L.) were studied under leaching conditions (2.3 mm per day). Grain yield increased strongly due to S application. Split application greatly increased the effectiveness of the sulfate fertilizers and appeared to be an effective tool in satisfying the S need of the crop under leaching conditions. Again, ES fertilizers were least effective, because the oxidation rate of ES was too slow to meet the S demand of the crop. In all experiments leaching losses of sulfate from the ES fertilizers were smaller than from the sulfate fertilizers.
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  • 91
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    Nutrient cycling in agroecosystems 39 (1994), S. 77-82 
    ISSN: 1573-0867
    Keywords: Acidic subsurface layer ; application rate ; North Carolina phosphate rock ; placement method ; time of application ; triple superphosphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using soils with an acidic subsurface layer, three glasshouse experiments were carried out to evaluate the effect of placement method and application rate of triple superphosphate (TSP) and North Carolina phosphate rock (NCPR) on dry matter (DM) yields. Time of application of NCPR on DM yield response of wheat was also studied. For Experiment 1, soil was collected in depth intervals of 0–2; 4–6; 6–8; and 8–10 cm from a red earth (chromic luvisol). The treatments included two P sources (TSP and NCPR), three placement methods (broadcast, banded or mixed into the subsurface layer, 6–8 cm), and six application rates. In this P deficient soil with an acidic subsurface layer, there was relatively little effect of application method of TSP on wheat yield responses. The maximum dry matter yield responses for broadcast, band and mix application methods was 30, 42 and 50 %, respectively. Responses to NCPR broadcast, band and mix methods were 20, 9 and 44 %, respectively. Mixing NCPR into to acidic subsurface layer produced yields similar to those from TSP although a higher application rate of P as NCPR was needed to achieve this outcome. Treatments for Experiments 2 and 3 were time of application of NCPR (0 and 30 days before sowing) and rate of application of NCPR (0 and 40 mg P/pot). In Experiment 2 (same soil as Experiment 1) application of NCPR prior to sowing, resulted in higher Colwell P concentration than when applied at sowing, but time of application had no effect on final DM yields. Experiment 3 used a red podzolic (chromic luvisol) soil which had a lower P-status, was more acid and had a lower exchangeable Ca2+ concentration than the red earth. Application of NCPR prior to sowing resulted in lower DM yield than when it was applied prior to sowing.
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  • 92
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    Nutrient cycling in agroecosystems 31 (1992), S. 15-19 
    ISSN: 1573-0867
    Keywords: Tillage ; crop rotation ; cereal grain ; wheat ; nitrogen ; sulfur ; phosphorus ; no-till
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Efficient fertilizer use is a prerequisite for achieving optimum crop yield while avoiding environmental contamination. Cereal response to nitrogen (N), sulfur (S), and phosphorus (P) were determined for 6 years under differing tillage [conventional-till (CT) vs. no-till (NT)] and intensity of cropping (cereal/fallow vs. cereal/cereal). Semidwarf white winter wheat (Triticum aestivum L.) alternated yearly with either fallow or spring cereal [barley (Hordeum vulgare L.) or spring wheat] on a Typic Haploxeroll soil in a 415 mm rainfall zone. Fertilizer treatments were no fertilizer (None), N only (N), N plus S (NS), and N plus S plus P (NSP). Average application rate, when applied, was 109 kg N, 18 kg S, and 11 kg P ha−1. Average cereal yield without fertilizer was 1.82 t ha−1. Nitrogen increased grain yield in 6 of 6, S in 4 of 6, and P in 3 of 6 years, with P and S response significant the remaining years at the 10% probability level. Average yield increases were 1.11 t ha−1 for N, 0.93 t ha−1 for S, and 0.47 t ha−1 for P. The NT/CT yield ratio was 0.60, 0.75, 0.93, and 0.95 with None, N, NS, and NSP addition, respectively, indicating that N and S deficiency were more severe in no-till. Limited increase in the NT/CT ratio with P addition indicated that P deficiency was less affected by tillage. Winter wheat always yielded less under NT than CT regardless of fertility, whereas spring cereals reached equality when fertilized with NSP. Annually-cropped wheat yielded 52, 67, 89, and 90% of wheat after fallow with None, N, NS, and NSP, respectively. Thus N and S, but not P, deficiency was more intense with increased frequency of cropping. Adequate fertility was a prime prerequisite for efficient yield in all systems.
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  • 93
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    Nutrient cycling in agroecosystems 32 (1992), S. 27-36 
    ISSN: 1573-0867
    Keywords: Phosphorus requirement ; wheat ; oats ; barley ; lupins ; triticale ; superphosphate ; grain yield ; phosphorus in grain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The phosphorus (P) requirement for grain production of different crop species (oats (Avena sativa), barley (Hordeum vulgare), triticale (xTriticosecale), narrow-leafed lupins (Lupinus angustifolius), and sandplain lupins (L. cosentinii) was compared with wheat (Triticum aestivum) in five field experiments on different lateritic soils in south-western Australia. Seven or eight levels of superphosphate were applied at the start of each experiment. The amount of P required to produce 70% (four experiments) or 90% (one experiment) of the maximum yield was used to compare P requirements. Large differences in the P requirements of the species were obtained. On P deficient soil in 3 experiments, oats required from 50 to 70% less P than wheat, but required 40% more P on a soil with a long history of superphosphate applications. Compared with wheat, in the year of P application, barley required 50% less P in one experiment, had similar P requirements in two experiments, and required 80% more P in another experiment. In the years after P application, barley required 20% less P in two experiments. On an acidic soil triticale required from 50% to 70% less P than wheat, but on less acidic soil it required 100% more P. In the year of P application, narrow-leafed lupins required 800% more P than wheat in one experiment, and 30% more P in the other experiment. In the year of P application, sandplain lupins required 70% less P than wheat in one experiment.
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  • 94
    ISSN: 1573-0867
    Keywords: nitrogen fertilizer rate ; electroultrafiltration ; wheat ; soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the investigation was to examine whether there exist relationships between the optimum nitrogen fertilizer rate for winter wheat and soil nitrogen fractions extracted by electroultrafiltration (EUF) from autumn samples of the upper soil layer (0–30 cm). Optimum nitrogen fertilizer rates were derived from grain yield curves of field trials carried out with increasing nitrogen fertilizer rates on 19 different sites in 1985/86 and 1986/87. Most soils were luvisols derived from loess, two soils were brown earths and one a pararendzina. Total Nitrogen fertilizer rates were 0, 40, 80, and 120 kg N/ha applied twice before ear emergence. The final nitrogen rate at ear emergence was the same for all treatments, namely 60 kg N/ha. Optimum nitrogen fertilizer rates were derived from the grain yield curve fitted to a modified Mitscherlich equation. The optimum nitrogen fertilizer rates were correlated with the nitrogen fractions extracted by EUF. The regression equation thus obtained showed that NO 3 - , the organic N fraction (EUF Norg), and the EUF Norg-quotient each had a highly significant impact on the optimum nitrogen fertilizer rate. The higher the amounts of EUF-N extracted the lower the optimum nitrogen rate. Substituting the EUF Norg-fraction for total nitrogen concentration in the upper soil layer gave a poorer relationship between the optimum nitrogen fertilizer rate and the soil data. In absolute terms the EUF Norg-fraction had by far the greatest impact on calculating the optimum nitrogen fertilizer rate. The investigation shows that the EUF method is a suitable technique for the determination of available soil nitrogen from which optimum nitrogen fertilizer rates can be derived for winter wheat cultivated under soil and climatic conditions typical for cereal growing areas in central Europe.
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  • 95
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    Nutrient cycling in agroecosystems 32 (1992), S. 185-194 
    ISSN: 1573-0867
    Keywords: Residual P ; P fixation ; Bray P ; Olsen P ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nineteen soils from the south east of the Province of Buenos Aires (Argentina) that had been fertilized with moderate amounts of P (10–40 kgP/ha) during the last 10 years were used to investigate the effect of time on the decline of P availability as measured by three soil tests (Bray 1, Bray 2, Olsen) and the null-point method. Differences in rates of P decline among soils and chemical methods were characterized by an exponential coefficient for time (b 2) in equations which describe the changes of the added P retained by the soil (Pr =ac b1 t b2). The rate of decline of P for the nineteen soils calculated for the soil test methods was ordered decreasingly as: null-point 〉 Olsen 〉 Bray 1 〉 Bray 2. The ability of the chemical methods for assessing the residual value of P for wheat growth (RV) was tested in a pot experiment on seven of the soils that differed in their individual rates of reaction with P. Differences between soils in the rate of reaction with P as measured in the laboratory by the null-point method and by the Olsen test were reflected in different residual values for P fertilizer for wheat plants. Thus the value ofb 2 for these methods was well correlated with the observed residual values. The soil properties commonly associated with the retention of P were not related to the value ofb 2 suggesting that more than one soil property may be involved in the measure ofb 2. The exponent for timeb 2 may be used as an index of the ability of the soil test to reflect the decline of P availability with time.
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  • 96
    ISSN: 1573-0867
    Keywords: Compost ; diammonium phosphate ; phosphorus availability ; fertilizer effectiveness ; 32P ; rock phosphate ; superphosphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The agronomic effectiveness of three P fertilizers (diamonium phosphate, rock phosphate and compost) was studied in a greenhouse experiment using wheat. A radioisotopic method, using triple superphosphate labelled with32P, was used to evaluate the P in dried tops that was derived from i) the soil, ii) labelled superphosphate and iii) the fertilizer being studied. The ratio between P uptake from each fertilizer and P uptake from the soil was used to compare the effectiveness of the different fertilizers. P derived from diammonium phosphate was greater than P derived from the soil, except in one soil. P derived from rock phosphate was always lower than P derived from the soil. The effectiveness of compost depended on soil type. Compost can produce two kind of effects: i) a direct P contribution and ii) an indirect effect improving P uptake from the soil. The radioisotopic method can be used to study the effectiveness of fertilizers even when there are no differences in yield.
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  • 97
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    Nutrient cycling in agroecosystems 40 (1994), S. 175-183 
    ISSN: 1573-0867
    Keywords: Nitrogen response ; on-farm research ; risk ; probability ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In many developing countries, fertilizer recommendations must be made in the absence of plant and soil analyses. When the region is variable in terms of soils, weather, and magnitude of response to fertilizer, a recommendation is likely to involve a high degree of risk for the farmer. Quantification of such risk is key to developing appropriate recommendations for the farmer. However, most methodologies generally used in analyzing fertilizer trials do not allow adequate quantification, especially as a continuous function, of the risk associated with a given recommendation. Three years of on-farm trials conducted in the High Valley of Mexico were used to evaluate different methodologies for generating N fertilization recommendations and their associated risk for wheat (Triticum aestivum) production in the absence of soil tests. When the traditional approach, using average yield responses or separate trial results, was used, an economic optimum was identified, but it was not possible to quantify the associated risk. In contrast, however, by using a combination of response surface methodology and simple probability analysis, the risk associated with any given recommendation was developed, even under the highly variable conditions of the study zone. The approach uses a treatment difference matrix (developed using average yield differences between a treatment and the zero N (0N) check) and its associated standard deviation over locations. From the matrix, an equation (being a function of N rate and relative grain:N price ratios) was developed that shows the probability of outperforming the 0N check for the economic optimum rate.
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  • 98
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    Nutrient cycling in agroecosystems 30 (1991), S. 1-7 
    ISSN: 1573-0867
    Keywords: Chloride ; pH ; residual effect ; sandy soil ; selenate ; selenite ; sulphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In areas where soils supply inadequate Se to crops to meet animal nutritional needs, it may be necessary to supplement Se in some fashion. This greenhouse experiment was designed to study the effect of selenate and selenite, incorporated with a Cl- or a SO4-based NPK (16-5-12) fertilizer added to a low-Se soil, on the Se concentration in wheat (Triticum aestivum L.). The sandy soil was limed to pH 5.5 and 6.5 prior to receiving 0, 0.03, or 0.06 mg Se kg−1 of soil with each NPK source each year for two years. The SO4-based NPK fertilizer treatment was used only at the 0.06 mg Se kg−1 rate. In the third year, the residual effect of the Se applied in the first 2 years was studied. The grain yield among treatments differed significantly but the effects of the rate or source were not consistent in all the years. However, significantly higher yields were obtained at pH 6.5 than at pH 5.5. Selenium concentration and uptake in wheat grain increased in proportion to the applied selenate but not selenite. However, selenite increased the Se concentration and uptake over the control. The concentration and uptake of Se were higher from selenate than from selenite. The effect of the Cl- and SO4-based NPK fertilizers was different on selenate and selenite. Selenium accumulation in wheat grain was greater from the Cl-based NPK fertilizer when selenate was used but it was greater from the SO4-based NPK fertilizer when selenite was used. The Se concentration in wheat, especially from selenate, was generally higher at the higher pH level except in the first year where it was higher at the lower pH level. The uptake of Se from the Se-enriched NPK fertilizers was generally as high as from the Se applied separately. The residual effect of both sources of Se applied in the first 2 years was very poor in the third year. The results suggest that the Se concentration in wheat grain can be increased by incorporating the Se salts in the NPK fertilizers but more selenate is recovered than selenite. Selenate should, however, be incorporated in a Cl-based NPK fertilizer to avoid the ionic competition from SO4 ions in the SO4-based NPK fertilizer. The uptake of Se is generally higher at pH 6.5 than at pH 5.5.
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    Nutrient cycling in agroecosystems 31 (1992), S. 215-219 
    ISSN: 1573-0867
    Keywords: Zinc fertilizer ; take-all (Gaeumannomyces graminis) ; wheat ; leaf Zn concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat plants were grown in field experiments with five levels of zinc (Zn) fertilizer applied to plots in 1983. The plots were continuously cropped with wheat to allow the build up ofGaeumannomyces graminis var.tritici (Ggt). For experiments 1 and 2, there were high levels of Ggt in the second and third years while for experiment 3 there were high levels of Ggt incidence in the third and fourth year of continuous cropping. The Zn status of the wheat plants, grain yield, and the incidence and severity of take-all were measured for every experiment each year. The Zn-deficient wheat plants were more severely infected by Ggt. However, increasing the Zn supply beyond that required for maximum grain yield had no further effects on decreasing the severity of take-all. The Zn concentration in the youngest emerged blade (YEB) suggested that the Zn status of the wheat plant ranged from severely Zn-deficient through marginal deficiency to sufficiency. The Zn-deficient wheat plant was more susceptible to Ggt infection than Zn-adequate plants. The severity of take-all in the final year was still high in Zn-adequate plants, suggesting high levels of applied Zn (11.2 kg Zn/ha in 1983) had no fungistatic effect on Ggt.
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    Nutrient cycling in agroecosystems 31 (1992), S. 43-49 
    ISSN: 1573-0867
    Keywords: Superphosphate ; nitrogen fertilizer ; take-all ; (Gaeumannomyces graminis) ; wheat ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat was grown continuously in soil amended with 5 levels of superphosphate and with 4 levels of urea at 3 sites. The incidence and severity of take-all, caused byGaeumannomyces graminis var.tritici, declined with increasing rates of application of both superphosphate and urea. In both years, the severity of take-all on plants receiving neither superphosphate nor urea was about 40% while at the highest level of superphosphate and urea supply the take-all severity was approximately halved at 22%. There was an increase in grain yield in response to applied superphosphate and urea to the highest level of each nutrient. There was also an increase in the 1,000-kernal weights with superphosphate and urea fertilizer application.
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