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  • maize  (73)
  • Springer  (73)
  • American Society of Hematology
  • Annual Reviews
  • Copernicus
  • Institute of Physics
  • 2005-2009
  • 1990-1994  (73)
  • 1980-1984
  • 1960-1964
  • 2007
  • 1991  (37)
  • 1990  (36)
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  • Springer  (73)
  • American Society of Hematology
  • Annual Reviews
  • Copernicus
  • Institute of Physics
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  • 2005-2009
  • 1990-1994  (73)
  • 1980-1984
  • 1960-1964
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 55 (1990), S. 285-294 
    ISSN: 1570-7458
    Keywords: Graminella nigrifrons ; maize ; oats ; johnsongrass ; development ; fecundity ; host suitability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La dynamique des populations (durée de développement de l'œuf à l'adulte, poids et taille des adultes, fécondité) de G. nigrifrons Forbes (Homop. Cicadellidae) a été étudiée au laboratoire à 5 températures sur plantules de maïs (Zea mays L.), avoine (Avena sativa L.) et sorgho vivace (Shorgum halepense (L.) Pers.). Sur les 3 plantes, les mâles se développent en moyenne 1,2 j plus vite que les femelles. Les relations entre vitesse de développement et température ont été déterminées en utilisant à la fois un modèle linéaire et le modèle biophysique à 2 paramètres de Sharpe & DeMichele (1977). Les températures plus basses donnent des adultes des 2 sexes plus gros et plus lourds. Moins de G. nigrifrons se sont développés sur la graminée vivace que sur les 2 graminées annuelles à la température la plus élevée (30°C), tandis qu'à la température la plus basse (18°C) moins de cicadelles se sont développées sur les graminées annuelles. La température semble jouer un rôle significatif en déterminant l'adéquation des plantes comme hôtes convenant au développement de G. nigrifrons. Le potentiel de ponte de cette cicadelle avait été sous-estimé par les étudies précédentes.
    Notes: Abstract Population dynamics of the blackfaced leafhopper, Graminella nigrifrons (Forbes) (Homoptera: Cicadellidae), was studied at five temperatures (18, 21, 24, 27, & 30°C) in the laboratory on seedling maize (Zea mays L.), oats (Avena sativa L.), and the perennial johnsongrass (Sorghum halepense (L.) Pers.). Effects of temperature and host plant on egg to adult mean development time, adult size and weight, and fecundity were determined. Leafhoppers on all three hosts developed fastest at the highest temperature tested (21.3 days), and slowest at the lowest temperature tested (73.2 days). The duration from first to last adult eclosion was shortest at 30°C, (11.5 days) and longest at 18°C (43 days). The sex ratio of males to females did not differ from 1:1, but males developed an average of 1.2 days faster than females on all three hosts. Mean percent development/day ranged from 1.4% at 18°C to 4.7% at 30°C. The relationship of this development rate and temperature was determined using both a linear model and a variable parameter biophysical model. Based on these models, the developmental threshold is estimated at 12–15°C. The lowest temperature yielded larger and heavier adults (312 μg, dry weight) than did the highest temperature (225 μg). Fewer leafhoppers developed on the perennial than the annuals at 30°C and fewer on the annuals than the perennial at 18°C. Our results suggest that early in the season johnsongrass and perhaps other perennials are the superior developmental hosts for this leafhopper, whereas in midsummer when temperatures are highest, annuals are the better hosts.
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  • 2
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    Entomologia experimentalis et applicata 61 (1991), S. 169-177 
    ISSN: 1570-7458
    Keywords: African migratory locust ; crop environment ; oviposition behaviour ; oviposition sites ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oviposition by the African migratory locust, Locusta migratoria migratorioides (Orthoptera: Acrididae), was studied in maize and wheat crops on the Orange Free State Highveld. Maize was shown to be the most important oviposition habitat with peak laying taking place in autumn and early winter when highest pod densities were recorded. Laying was mainly concentrated along the middle of the crop interrows in maize and within clearings in the wheat crop. Despite the uniform layout of these crops, the distribution of egg pods was found to be aggregated. Non-reproductive behaviour, such as locust aggregation, basking and feeding, as well as environmental factors appeared to influence the distribution of egg pods in these crops. Secondary selection for optinum soil moisture and compaction on the laying site enhanced the aggregation of pods.
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  • 3
    ISSN: 1573-0832
    Keywords: Fusarium ; maize ; moniliformin ; mycotoxins ; trichothecenes ; zearalenone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Forty Fusarium isolates obtained from maize fields were screened for moniliformin production on maize kernels. Twelve isolates, including seven of F. subglutinans, were found to produce moniliformin at levels ranging from 0.4 to 64 ppm. Twenty six isolates were also screened for production of deoxynivalenol, diacetoxyscirpenol, T-2 toxin and zearalenone. Of these, 22, including all 11 isolates of F. graminearum, produced zearalenone at levels ranging from 0.1 to 96.0 ppm, while 13 produced T-2 toxin at low levels, (〈1.1 ppm). Deoxynivalenol and diacetoxyscirpenol were each produced by six isolates, also at low levels (〈1.0 ppm). Three isolates of F. graminearum and one of F. sambucinum produced four toxins simultaneously.
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  • 4
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    Nutrient cycling in agroecosystems 23 (1990), S. 73-80 
    ISSN: 1573-0867
    Keywords: Nigerian savanna ; maize ; potassium ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A three year field study was conducted at five locations in the Nigerian savanna to evaluate the response of early maturing maize variety to varying rates of K and Zn with a view to establishing the K and Zn requirements for maize production in this zone. Treatments consisted of 4 × 3 factorial combinations of 4 levels of K and 3 levels of Zn. Responses to K and Zn fertilization were sporadic and were obtained only in soils of the Southern Guinea savanna and in the soil formed on sedimentary sandstone. There seem to be no problem at present in soils of the Northern Guinea and Sudan savannas where leaching is less intense. It is inferred from this study that K and Zn deficiences are incipient in the high rainfall soils and in the sandstone derived soils. For these soils, 50 kg K/ha and 2–5 kg Zn/ha is suggested as adequate for an early maturing maize crop. Soil data showed that K and Zn responses can be expected when available K and Zn levels fall below 0.1 meq/100 g and 2 ppm respectively.
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  • 5
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    Nutrient cycling in agroecosystems 26 (1990), S. 249-252 
    ISSN: 1573-0867
    Keywords: Long-term manure trial ; residual effect ; model test ; nitrogen availability ; maize ; Italian ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sluijsmans and Kolenbrander developed a simple model to describe the availability of animal manure, assuming a readily available, an easily decomposable and a slowly decomposable N fraction. We tested this model on data from an experiment in which farmyard manure had been applied for eleven successive years to silage maize [Zea mays L.] grown on a light sandy soil. The residual effects of this FYM were then measured by growing Italian ryegrass [Lolium multiflorum Lamk.] in the 12th year. The measured uptake of N by the grass of the FYM residues was then compared with the computed values. The measured amounts of N taken up agreed fairly well with the calculated amounts for applications of 50 and 100 t FYM per ha per year. If the rates of manure application are adjusted to crop requirement, the model shows that the potential, long-term release of N from the residual N fraction of FYM will not exceed 20 kg N per ha. For cattle slurry with a smaller residual fraction, the release will be at most 10% of the total annual N application.
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  • 6
    ISSN: 1573-4927
    Keywords: mutator ; transposable element ; alcohol dehydrogenase ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A secondary mutant, derived from an allele of maize alcohol dehydrogenase 1 (Adh1) carrying a Mutator transposable element (Mu1) in its first intron, was reported to exhibit a threefold decrease in ADH enzymatic activity and steady-state RNA levels compared to the original mutant. The original mutant,Adh1-S3034 (abbreviatedS3034), was previously characterized at the molecular level. The derivative, abbreviatedS3034b, has now been cloned; at the DNA sequence level the insertion and surroundingAdh1 sequences are indistinguishable fromS3034. Furthermore, in our lines there is no difference in relative ADH activities between products of the two putative alleles. A comparison of gene expression in heterozygotes obtained by crossing to different tester lines reveals a correlation between the measured decrease in levels of ADH polypeptide produced by the mutant allele and the background in which it is measured; this effect is distinct from any background-related variation in the expression of the progenitor allele. It does not appear to be attributable to alternative patterns of DNA modification. It appears to reflect a background-associated difference in the level of normalAdh1-RNA produced. Thus the previously reported distinction betweenS3034 andS3034b may be due to differences in the extent to which the mutant allele and a given genetic background interact to produce functionalAdh1-RNA.
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  • 7
    ISSN: 1573-1561
    Keywords: Leafhopper ; Dalbulus maidis ; Homoptera ; Cicadellidae ; hostfinding ; maize ; visual ; olfactory ; synergism ; pest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Virtually nothing is known about the role plant volatiles play in host-finding by Homoptera in the Suborder Auchenorrhyncha. In laboratory bioassays, we examined the influence of plant volatiles on orientation and postcontact behaviors of the leafhopper,Dalbulus maidis, and determined the relationship between visual and olfactory stimuli during host-finding. When compared to the number of contacts made with reflected green light in the presence of a hexane control,D. maidis made more contacts when exposed to volatile extracts from its preferred host, maize; a similar number of contacts when exposed to volatiles from a marginal host, gamagrass; and fewer contacts when exposed to volatiles from a nonhost, sorghum. There was no difference between males and females in the number of contacts made with green light when exposed to maize volatiles compared to hexane alone. More contacts were made with green light than with white light of similar intensity, both in the presence and in the absence of olfactory stimuli; however, maize volatiles acted as a Synergist by increasing the number of contacts leafhoppers made with green light. After contacting the green light, exposure of maize volatiles significantly increased, relative to hexane, the amount of stationary time, but did not influence the amount of time spent moving, the distance traveled, or the speed while moving when within the boundaries of the green light. This study provides the first evidence for an interaction between visual and olfactory stimuli during host-finding for a leafhopper and also for olfactory mediation of postcontact behaviors not associated with feeding.
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  • 8
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    Plant molecular biology 14 (1990), S. 333-347 
    ISSN: 1573-5028
    Keywords: intergenic spacer ; maize ; methylation ; rDNA ; teosinte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The restriction endonucleases Hpa II and Msp I were used to examine cytosine methylation in the ribosomal RNA genes (rDNA) of inbred lines of maize and species of teosinte. In all of the rDNAs examined, Msp I (not sensitive to mCpG) digestion yielded a distribution of lower molecular weight fragments indicative of multiple recognition sites. The majority of the rDNA arrays in an individual were inaccessible to Hpa II (sensitive to mCpG) cleavage, but a significant fraction (10–25%) was cleaved at least once by Hpa II into repeat unit length fragments (9.1 kbp). In some maize inbred lines, one or two additional fragment populations (less than 9.1 kbp in length) were also produced by Hpa II digestion. All of the unmethylated Hpa II sites mapped to the intergenic spacer (IGS), and the major unmethylated site was located approximately 800 bp 5′ to the start of the 18S RNA coding sequence. An Eco RI polymorphism, present in the 26S gene of certain inbred lines and hybrids, was utilized to investigate the organization of unmethylated repeat units in the rDNA array. In double digest experiments with Hpa II/Eco RI, the fragments from repeat units with two Eco RI sites were sensitive to Hpa II digestion, whereas, the fragments from repeat units with a single Eco RI site were almost completely resistant to Hpa II digestion. Similar digestion patterns were also observed in Eco RII (sensitive to mCNG)/Eco RI digests. These results suggest that unmethylated and Eco RI polymorphic sites occur in the same repeat units.
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  • 9
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    Plant molecular biology 15 (1990), S. 783-785 
    ISSN: 1573-5028
    Keywords: sorghum ; maize ; glycine-rich proteins ; RNA-binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
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    Plant molecular biology 16 (1991), S. 919-923 
    ISSN: 1573-5028
    Keywords: Zea mays ; maize ; embryogenesis ; abscisic acid ; seed maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated by differential hybridization a cDNA, termed Emb564, which is complementary to an 800 nt embryo-specific transcript in Zea mays. The expression of Emb564 can be enhanced by exogenous abscisic acid (ABA) and the effect of ABA on the accumulation of Emb564 transcript appears to be confined to embryos at the early and mid embryonic stages. In addition, Emb564 is expressed at low levels in ABA-deficient but not in ABA non-responsive embryos. Genomic analysis suggested that the Emb564 mRNA is encoded by a single gene. Sequence analysis showed that Emb564 exhibits extensive similarities with several known ABA-inducible genes.
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  • 11
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    Plant molecular biology 16 (1991), S. 935-936 
    ISSN: 1573-5028
    Keywords: maize ; mitochondrial DNA ; repeated sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 12
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    Plant molecular biology 17 (1991), S. 1259-1261 
    ISSN: 1573-5028
    Keywords: anaerobic genes ; maize ; pyruvate decarboxylase ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 13
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    Plant molecular biology 14 (1990), S. 1-15 
    ISSN: 1573-5028
    Keywords: cDNA ; differential screening ; genomic cloning ; maize ; tandem genes ; α-tubulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The identification of a cDNA (MR19) corresponding to a maize α-tubulin and homologous genomic clones (MG19/6 and MG19/14) is described. The cDNA has been isolated by differential screening of a cDNA maize root library. We have found two α-tubulin genes in a tandem arrangement in the genomic clones, separated by approximately 1.5 kbp. One of the genes (gene I) contains an identical nucleotide sequence which corresponds to the cDNA clone. The two deduced proteins from DNA sequences are very similar (only two conservative replacements in 451 amino acids) and they share a high homology as compared with the published α-tubulin sequences from other systems and in particular with the Arabidopsis thaliana and Chlamydomonas reinhardtii sequences reported. The structure of both genes is also very similar; it includes two introns, of 1.7 kbp and 0.8 kbp respectively, in each gene and only one intron placed at a homologous position in relation to Arabidopsis thaliana genes. By using specific 3′ probes it appears that both genes are preferentially expressed in the radicular system of the plant. The α-tubulin gene family of Zea mays seems to be represented by at least 3 or 4 members.
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  • 14
    ISSN: 1573-5028
    Keywords: maize ; Coix ; zein ; coixin ; phylogenetic relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zeins from Zea mays L cv. Maya and coixins from Coix lacryma-jobi L. cv. Adlay were fractionated to obtain α-, β-, and γ-zein and α-, β-, and γ-coixin. The α-coixins were composed of 4 polypeptide classes of 27 kDa (C1), 25 kDa (C2), 17 kDa (C4) and 15 kDa (C5) with solubility properties very similar to those of the 22 kDa and 19 kDa α-zeins. Like the α-zeins, the C1 and C2 α-coixins corresponded to 80% of total Coix prolamins. The fraction corresponding to γ-coixin contained only one protein band of 22 kDa (C3). This coixin fraction has solubility properties similar to those of γ-zein and represents 15% of the total coixin. The β-zein fraction was composed of a major 17 kDa protein band, while the β-coixin fraction consisted of a mixture of α- and γ-coixins. Polyclonal antibodies raised against C1 recognized C1 and C2 and cross-reacted strongly with the 22 kDa α-zein, as did C4 and C5 antisera. The antiserum against γ-coixin showed strong cross-reaction with γ-zein. The homology between coixins and zeins was further investigated by using Southern hybridization analyses. The genomic DNA of maize and Coix were digested with several restriction enzymes and probed with cDNA clones representing 19 and 22 kDa α-zeins as well as the 28 and 16 kDa γ-zeins. The Coix genome showed complex cross-hybridization sequences with the 22 kDa α-zein cDNA, while no cross-hybridization was observed with the 19 kDa cDNA clone. The cDNA clone representing the 28 kDa γ-zein cross-hybridized with only one band of Coix genomic DNA, in contrast to the three bands observed in maize. This same Coix sequence also cross-hybridized with the cDNA clone representing the 16 kDa γ-zein. The relevance of these findings are discussed in the context of the origin of zein and coixin genes.
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  • 15
    ISSN: 1573-5028
    Keywords: anaerobic stress ; enolase ; gene regulation ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding maize enolase (2-phospho-D-glycerate hydrolase) was purified by functional genetic complementation using an enolase deficient mutant of Escherichia coli, DF261. This cDNA, pZM245, was characterized by restriction mapping and DNA sequence analysis. The cDNA contained an open reading frame encoding a protein of 446 amino acids with a high degree of similarity to enolase sequences from other organisms (72% identity to yeast enolase and 82% identity to human enolase). The pZM245 contains a correctly positioned consensus prokaryotic translation initiation sequence. The specific activity of enolase in maize increases to about twice its initial level after 48 hours of anaerobiosis. Northern-blot analysis showed a five-fold anaerobic induction in enolase mRNA, while heat shock or cold shock increased enolase mRNA levels only slightly. Southern-blot analysis of maize genomic DNA indicated that there is one copy of the pZM245 hybridizing sequence per haploid genome in maize.
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  • 16
    ISSN: 1573-5028
    Keywords: cDNA family ; maize ; pollen-expressed genes ; polygalacturonase ; signal peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length cDNA clone, named PG1, abundantly expressed in late stages of pollen development, has been isolated from a cDNA library using a differential screening method with cDNA probes representative of microspores at early or late developmental stages. The encoded 410 amino acid polypeptide has significant homology with various polygalacturonases (PG) described elsewhere. Two polypeptides, of 49 and 53 kDa respectively, have been identified in the active PG fraction, isolated from mature pollen by immuno-cross-reaction with tomato PG antibodies. According to their N-terminal sequence, they can be identified as being mature peptides encoded by the PG1 cDNA clone. We propose that these two proteins derive from a unique precursor through several post-translational events, including the excision of a 22 amino-terminal signal peptide and glycosylation. PG-encoding genes form a small genomic family. Sequence analysis of three PG cDNA clones shows that they are closely related. The divergence of nucleotides between these three cDNA clones is 1%. They encode the same product.
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  • 17
    ISSN: 1573-5028
    Keywords: expression ; germination ; histone genes ; maize ; subfamilies ; tissues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The steady-state levels of H3 and H4 mRNAs transcribed from three H3 and two H4 multigene subfamilies were studied during germination and in different organs of maize. During germination the five subfamilies are expressed in parallel to DNA synthesis, but a 5-fold difference in the quantity of mRNAs transcribed per gene copy was found from our subfamily to another. In adult plants H3 and H4 mRNA levels are highest in organs containing meristematic tissues but also high in non-proliferating tissues. No strict tissue specificity expression could be detected but some subfamilies show preferential expression in some tissues.
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  • 18
    ISSN: 1573-5028
    Keywords: maize ; ABA-induced gene ; protein phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ABA-induced MA12 cDNA from maize, which encodes a set of highly phosphorylated embryo proteins, was used to isolate the corresponding genomic clone. This gene, called RAB-17 (responsive to ABA), encodes a basic, glycine-rich protein (mol. wt. 17 164) containing a cluster of 8 serine residues, seven of them contiguous. It is a homologue of the rice RAB-21 gene (Mundy J, Chua NH, EMBO J 7; 2279–2286, 1988). Phosphoamino acid analysis of the isolated protein indicates that only the serine residues are phosphorylated and a putative casein-type kinase phosphorylatable sequence was identified in the protein. The pattern of expression and in vivo phosphorylation of the RAB-17 protein was studied during maize embryo germination and in calli of both meristematic or embryonic origin. ABA treatment induced the synthesis of RAB-17 mRNA and protein in calli, however, the RAB-17 proteins were found to be highly phosphorylated only in embryos.
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  • 19
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    Plant molecular biology 15 (1990), S. 913-920 
    ISSN: 1573-5028
    Keywords: Adh1 ; chloramphenicol acetyl transferase ; enhancer ; intron ; maize ; transient expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chimeric genes containing the coding sequence for bacterial chloramphenicol acetyl transferase (CAT) have been introduced by electroporation into maize protoplasts (Black Mexican Sweet) and transient expression monitored by enzyme assays. Levels of CAT expression were enhanced 12-fold and 20-fold respectively by the inclusion of maize alcohol dehydrogenase-1 introns 2 and 6 in the chimeric construct. This enhancement was seen when the intron was placed within the 5′ translated region but not when it was located upstream of the promoter or within the 3′ untranslated region. Deletion of exon sequences adjacent to intron 2 abolished its ability to mediate enhancement of CAT gene expression. Northern analysis of protoplasts electroporated with intron constructs revealed elevated levels of CAT mRNA. However, this elevation was insufficient to account for the increased enzyme activity. One explanation of these results is that splicing affects both the quantity of mRNA.
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  • 20
    ISSN: 1573-5028
    Keywords: germination ; fungi ; maize ; pathogenesis-related ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pathogenesis-related proteins (PRs) are plant proteins produced in leaves in response to infection by pathogens including viruses, viroids, fungi and bacteria. Information on the presence and/or expression of PRs in monocotyledonous plants is scarce. Here we report the identification of cDNA and genomic clones coding for a basic form of a protein from germinating maize seeds having a high homology with the group of PR-1 from tobacco. A cDNA library enriched in aleurone-specific sequences was prepared from maize seeds two days after germination. One clone was found to contain an open reading frame encoding a protein homologous to PR proteins from tomato (p14) and tobacco (PR-1 group). Sequence analysis of the corresponding genomic clone revealed that it was encoded by a single exon. Besides, DNA blot hybridization indicates that this PR-like protein is encoded by a single-copy gene in maize. The accumulation of its mRNA increases after rehydration of desiccated seeds. Furthermore, a relationship was found between its expression and infection by a natural pathogen of maize, the fungus Fusarium moniliforme. The possible role of this protein as a response mechanism following fungal infection in cereal seeds is discussed.
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  • 21
    ISSN: 1573-5028
    Keywords: heat shock ; heat shock cDNAs ; maize ; small heat shock proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heat-shocked maize seedlings (cv. Oh43) synthesize a characteristic set of heat-shock proteins (hsps) which include an 18 kDa family containing at least six major isoelectric variants. A cDNA library was constructed from poly(A)+ RNAs isolated from the radicles of heat-shocked maize seedlings and screened with a DNA fragment from the theoretical open reading frame of a putative Black Mexican Sweet maize hsp 18 genomic clone. Two clones, cMHSP18-3 and cMHSP18-9, were isolated, and the RNA transcripts generated from them were translated into proteins which immunoreact with antibodies directed against the maize 18 kDa hsps and exhibit the same electrophoretic characteristics as two different members of the 18 kDa hsp family. Nucleotide sequence analyses of the cDNAs in these clones reveal that their 5′ and 3′ untranslated regions exhibit 33–34% identity and that their protein encoding regions share 93% identity. The deduced amino acid sequences of these clones show 90% identity, and the apparent molecular masses and isoelectric points of these proteins agree with those established for two different 18 kDa hsps, numbered 3 and 6. This report substantiates that at least two of the 18 kDa hsps in maize are products of different but related genes. Moreover, it establishes that transcripts for these proteins accumulate during heat shock and that both their nucleotide and deduced amino acid sequences share extensive similarities with the class VI small hsps in soybean and with transcripts expressed during meiosis in Lilium.
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  • 22
    ISSN: 1573-5028
    Keywords: enhanced gene expression ; exon ; intron ; maize ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Both exon 1 and intron 1 of the maize Shrunken-1 (Sh1) gene individually stimulate expression of reporter genes in transient gene expression experiments if present within the transcription unit. The Sh1 exon 1 mediates a 10-fold increase in activity when inserted at the 5′ end of the bacterial chloramphenicol transacetylase (CAT) marker gene in both monocot and dicot protoplasts. The Sh1 intron 1 enhances chimeric gene expression in rice and maize protoplasts approximately 100-fold but inhibits CAT expression in tobacco protoplasts. In combination, the stimulatory effects of Sh1 exon 1 and intron 1 are multiplicative in monocot protoplasts resulting in a final enhancement of up to 1000-fold compared to the unmodified CAT or luciferase marker genes.
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  • 23
    ISSN: 1573-5028
    Keywords: anthocyanin ; B-Peru ; maize ; transcription activator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 24
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    Plant molecular biology 17 (1991), S. 305-307 
    ISSN: 1573-5028
    Keywords: adenine nucleotide translocator ; ADP/ATP translocase ; mitochondria ; maize ; inner mitochondrial membrane
    Source: Springer Online Journal Archives 1860-2000
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  • 25
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    Plant molecular biology 17 (1991), S. 361-369 
    ISSN: 1573-5028
    Keywords: chloroplast genome ; cloning in YACs ; maize ; stability analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 139 kb circular maize chloroplast genome was cloned in a linear form in a single yeast artificial chromosome (YAC), and several such clones were then analyzed to study the stability of large DNA sequences in YACs. The YAC clones were isolated from a partial maize DNA YAC library. The library was constructed byBal-31 nuclease digestion of high-molecular-weight total maize genomic DNA followed by blunt-end ligation into a modified YAC vector, pYAC11. All chloroplast genome-containing YACs (cpYACs) were characterized by comparing their restriction enzyme digestion patterns with that of purified maize chloroplast DNA (MCD). Comparison of the restriction patterns of four cpYACs, MY503, MY504, MY518 and MY526, with that of MCD did not show any change in the size of the restriction fragments except at the chloroplast DNA-vector junction fragments. These altered size fragments were confirmed as junction fragments by hybridization of the pYAC11 border fragments. The end-specific T3 and T7 transcripts synthesized from MY503 also identified the same junction fragments as did the pYAC11 border fragments. Most cpYACs were completely stable through the analyzed one hundred generations.
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  • 26
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    Plant molecular biology 17 (1991), S. 679-690 
    ISSN: 1573-5028
    Keywords: herbicide safener ; maize ; inducible plant genes ; differential gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A search of compounds capable of inducing specific gene expression in plants without affecting growth and development led to the examination of changes in the pattern of gene expression in corn after treatment with substituted benzenesulfonamide herbicide safeners. Following hydroponic treatment of corn with the safener N-(aminocarbonyl)-2-chlorobenzenesulfonamide (2-CBSU), the specific induction of new translatable mRNA species was observed. Replicate copies of a cDNA library made using RNA from 2-CBSU-treated corn roots were differentially screened with cDNA probes made from either the same mRNA fraction used for library construction or mRNA isolated from roots treated with 2-chlorobenzenesulfonamide (2-CBSA), an inactive analog of the safener. Colonies showing hybridization only with the probe made using mRNA from 2-CBSU-treated roots were further characterized to assess the specificity of the induction and decay of the corresponding induced RNA species. RNA blot analyses showed two clones, designated In2-1 and In2-2, contained plasmids that hybridized to RNAs that were induced from an undetectable background in corn roots within 30 minutes after treatment with 2-CBSU. Leaf and meristem tissues showed similar inductions of the In2-1 and In2-2 RNA species after a delay of several hours. In addition, both RNA species were induced in corn by foliar application of 2-CBSU. In contrast, neither RNA species was induced following stress treatments of plants. These results indicate a substituted benzenesulfonamide safener might be used with the promoters from the In2-1 and In2-2 genes to develop a new inducible gene expression system for plants.
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  • 27
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    The journal of membrane biology 121 (1991), S. 11-22 
    ISSN: 1432-1424
    Keywords: channel ; protoplast ; K+ current ; patch clamp ; corn ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Whole-cell sealed-on pipettes have been used to measure electrical properties of the plasmalemma surrounding protoplasts isolated from Black Mexican sweet corn shoot cells from suspension culture. In these protoplasts the membrane resting potential (V m ) was found to be −59±23 mV (n=23) in 1mm K o − . The meanV m became more negative as [K−] o decreased, but was more positive than the K+ equilibrium potential. There was no evidence of electrogenic pump activity. We describe four features of the current-voltage characteristic of the plasmalemma of these protoplasts which show voltagegated channel activity. Depolarization of the whole-cell membrane from the resting potential activates time- and voltage-dependent outward current through K+-selective channels. A local minimum in the outward current-voltage curve nearV m =150 mV suggests that these currents are mediated by two populations of K+-selective channels. The absence of this minimum in the presence of verapamil suggests that the activation of one channel population depends on the influx of Ca2+ into the cytoplasm. We identify unitary currents from two K+-selective channel populations (40 and 125 pS) which open when the membrane is depolarized; it is possible that these mediate the outward whole-cell current. Hyperpolarization of the membrane from the resting potential produces time- and voltage-dependent inward whole-cell current. Current activation is fast and follows an exponential time course. The current saturates and in some cases decreases at membrane potentials more negative than −175 mV. This current is conducted by poorly selective K+ channels, whereP Cl/P K=0.43±0.15. We describe a low conductance (20 pS) channel population of unknown selectivity which opens when the membrane is hyperpolarized. It is possible that these channels mediate inward whole-cell current. When the membrane is hyperpolarized to potentials more negative than −250 mV large, irregular inward current is activated. A third type of inward whole-cell current is briefly described. This activates slowly and with a U-shaped current-voltage curve over the range of membrane potentials −90〈V m 〈0 mV.
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  • 28
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    Plant and soil 124 (1990), S. 221-225 
    ISSN: 1573-5036
    Keywords: maize ; pollen fertility ; Zea mays L. ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Zinc deficiency decreased pollen viability in maize (Zea mays L. cv. G2) grown in sand culture. On restoring normal zinc supply to zinc-deficient plants before the pollen mother cell stage of anther development, the vegetative yield of plants and pollen fertility could be recovered to a large extent, but the recovery treatment was not effective when given after the release of microspores from the tetrads. If zinc deficiency was induced prior to microsporogenesis it did not significantly affect vegetative yield and ovule fertility, but decreased the fertility of pollen grains, even of those which visibly appeared normal. If the deficiency was induced after the release of microspores from the tetrads, not only vegetative yield and ovule fertility but pollen fertility also remained unaffected.
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  • 29
    ISSN: 1573-5036
    Keywords: maize ; nutrient concentration ; nutrient availability ; root growth ; root zone temperature ; shoot growth ; shoot meristem temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize seedlings were grown for 10 to 20 days in either nutrient solution or in soils with or without fertilizer supply. Air temperature was kept uniform for all treatments, while root zone temperature (RZT) was varied between 12 and 24°C. In some treatments the basal part of the shoot (with apical shoot meristem and zone of leaf elongation) was lifted up to separate the indirect effects of root zone temperature on shoot growth from the direct effects of temperature on the shoot meristem. Shoot and root growth were decreased by low RZT to a similar extent irrespective of the growth medium (i.e. nutrient solution, fertilized or unfertilized soil). In all culture media Ca concentration was similar or even higher in plants grown at 12 as compared to 24°. At lower RZT concentrations of N, P and K in the shoot dry matter decreased in unfertilized soil, whereas in nutrient solution and fertilized soil only the K concentration decreased. When direct temperature effects on the shoot meristem were reduced by lifting the basal part of the shoot above the temperature-controlled root zone, shoot growth at low RZT was significantly increased in nutrient solution and fertilized soil, but not in unfertilized soil. In fertilized soil and nutrient solution at low RZT the uptake of K increased to a similar extent as plant growth, and thus shoot K concentration was not reduced by increasing shoot growth rates. In contrast, uptake of N and P was not increased, resulting in significantly decreased shoot concentrations. It is concluded that shoot growth at suboptimal RZT was limited both by a direct temperature effect on shoot activity and by a reduced nutrient supply through the roots. Nutrient concentrations in the shoot tissue at low RZT were not only influenced by availability in the substrate and dilution by growth, but also by the internal demand for growth.
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  • 30
    ISSN: 1573-5036
    Keywords: maize ; sorghum ; spore production ; VAM fungi ; water-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays) and sorghum (Sorghum bicolor) were inoculated with a range of VAM fungi and grown under water-stressed and unstressed conditions. There was considerable variation amongst the inocula in their effects on plant growth. Inoculation with Glomus clarum produced the biggest plants in each host, with Glomus monosporum and Acaulospora sp. giving the least growth overall. Root infection produced by the different inocula also varied, but levels were not correlated with effects on plant growth. Water-stress reduced plant growth, with the effects not being altered by mycorrhizal infection. VAM infection levels were not affected by water-stress. Spore production from most inocula was reduced by water-stress, both in total spore numbers and in terms of spores per gram plant weight. Sporulation of G. clarum, G. epigeum and G. monosporum were affected less by stress than were the other inocula. Spore production was in general greater on sorghum than on maize, but the host effect varied amongst the inocula.
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  • 31
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    Plant and soil 127 (1990), S. 237-241 
    ISSN: 1573-5036
    Keywords: Fusarium moniliforme ; Macrophomina phaseolina ; maize ; organic amendment ; stalk rot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Five organic materials, Calopogonium sp. leaves, rice straw, mixed wood saw dust of Terminalia sp. Triplochyton sp. and Kaya sp., fresh guinea grass and poultry manure were added to soil with a recent history of high stalk rot of maize caused by Macrophomina phaseolina and Fusarium moniliforme. The two stalk rot organisms reacted differently to the organic amendments. All the amendments produced significantly less Fusarium stalk rot disease than the unamended control. Amendment of soil with fresh Calopogonium leaves was almost ineffective in controlling the incidence of Macrophomina phaseolina. Organic amendment with poultry manure increased the disease casued by M. phaseolina. The other amendments appeared to be equally effective in checking the disease. Increased microbial population due to amendment may play some role in disease suppression.
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  • 32
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    Plant and soil 131 (1991), S. 59-66 
    ISSN: 1573-5036
    Keywords: maize ; mechanical stress ; penetrometer ; root growth ; sandy loam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root penetration resistance and elongation of maize seedling roots were measured directly in undisturbed cores of two sandy loam soils. Root elongation rate was negatively correlated with root penetration resistance, and was reduced to about 50 to 60% of that of unimpeded controls by a resistance of between 0.26 and 0.47 MPa. Resistance to a 30° semiangle, 1 mm diameter penetrometer was between about 4.5 and 7.5 times greater than the measured root penetration resistance. However, resistance to a 5° semiangle, 1 mm diameter probe was approximately the same as the resistnace to root penetration after subtracting the frictional component of resistance. The diameter of roots grown in the undisturbed cores was greater than that of roots grown in loose soil, probably as a direct result of the larger mechanical impedance in the cores.
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  • 33
    ISSN: 1573-5036
    Keywords: cassava ; Guelph permeameter ; leaching ; maize ; methylene blue ; rice ; rooting depth ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under high rainfall conditions on acid soils with shallow crop root systems the rate of N leaching is high. A simple model predicts nitrogen uptake efficiency as a function of the amount of rainfall in excess of evapotranspiration, rooting depth and degree to which N leaching is retarded in comparison with water transport. Field observations on acid soils in S.E. Nigeria and S. Sumatera (Indonesia) showed that this model should be amended to include the role of old tree root channels. Crop roots can follow these channels, which are coated with partly decayed organic matter, into the acid subsoil. Measurements of water infiltration with a Guelph permeameter and a methylene blue dye showed that such channels form the major infiltration sites during rainstorms. Implications for nitrogen use efficiency and cropping pattern are discussed.
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  • 34
    ISSN: 1573-5036
    Keywords: aluminium ; calcium ; groundnut ; gypsum ; limestone ; magnesium ; maize ; soil solution ; ultisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted on an Ultisol in Malaysia to assess changes in soil solution composition and their effects on maize and groundnut yields, resulting from limestone and gypsum application. The results showed that soil solution Ca in the lime treatment remained mainly in the zone of incorporation, but in the gypsum treatment some Ca moved into 15–30 cm zone. Al3+ and AlSO4 + were dominant Al species in the soil solution of nil treatment. Liming decreased Al3+ and AlSO4 +, but increased hydroxy-Al monomer activities. However, gypsum application resulted in an increase of AlSO4 + activity and in a decrease of Al3+ activity. Relative maize and groundnut yields were negatively correlated with Al3+, Al(OH)2+ and Alsum activities. Likewise, relative yields were negatively correlated with Al concentration and the Al concentration ratio and positively correlated with soil solution Mg concentration and Ca/Al ratio.
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  • 35
    ISSN: 1573-5036
    Keywords: cadmium ; copper ; extraction method ; iron ; maize ; manganese ; nickel ; root exudate ; tobacco ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soluble root exudates were collected from three plants (Nicotiana tabacum L., Nicotiana rustica L. and Zea mays L.), grown under axenic and hydroponic conditions, in order to study their metal-solubilizing ability for Cd and other cations (Cu, Fe, Mn, Ni, Zn). Nicotiana spp. and Zea mays L. root exudates differed markedly in C/N ratio, sugars vs. amino acids ratio and organic acids content. Metals from two soils were extracted with either root exudate solutions, containing equal amounts of organic carbon, or distilled water as control. In the presence or absence of root exudates, the solubility of Fe and Mn was much higher than of the four other metals tested. Root exudates increased the solubilities of Mn and Cu, whereas those of Ni and Zn were not affected. Root exudates of Nicotiana spp. enhanced the solubility of Cd. The extent of Cd extraction by root exudates (N. tabacum L. N. rustica L. Zea mays L.) was similar to the order of Cd bioavailability to these three plants when grown on soil. An increase in Cd solubility in the rhizosphere of apical root zones due to root exudates is likely to be an important cause of the relatively high Cd accumulation in Nicotiana spp.
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  • 36
    ISSN: 1573-5060
    Keywords: Breeding ; heritability ; in vitro digestibility ; in vivo digestibility ; maize ; silage maize ; variation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation and covariation for agronomic and digestibility traits of silage maize are reported from a compilation of 22 years of experiments with standard sheep. Genotype effects of DOM and DCF were highly significant, even when genotypes were nested in earliness groups or brown-midrib hybrids discarded (Table 2). The genetic variance of crude fiber content was low, but the variance of the DCF was high. The genetic variance of DOM was about 4 times lower than genetic variance of DCF, but broad sense heritability of DOM was higher because of lower residual variance (Table 3). Genetic correlations between grain or crude fiber content and DOM had similar absolute values, 0.65, so each of these two traits was an important but not the unique determinant of silage maize quality. There was no correlation between DCF and grain or crude fiber content. Yield was not related to DOM or DCF within each group of earliness, allowing some quality improvement without agronomic drift (Table 4). Except for late hybrids, most of DOM differences between groups of earliness came from lowering of minimum value, while maximum values were similar. It was the contrary for DCF, with similar minimum values for all groups (Table 5). There was no obvious correlation between year of registration of hybrids and DOM or DCF, but extra new variation seemed obtained only for low values (Figs 1, 2; Table 6). IVDOM according to the APC process was a poor predictor of DOM, especially when brown-midrib hybrids and earliness effects were discarded; but because heritability of this trait was similar to DOM heritability, such enzymatic processes could probably be used to avoid drift towards poor DOM with hybrids bred for higher stalk strength.
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  • 37
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    Euphytica 46 (1990), S. 237-247 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; genetic variation ; prediction ; dry matter yield ; early vigour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Evidence of genetic variation for early vigour is presented using maize line × tester crosses. The leaf appearance rate and associated variance components are affected by a physiological stress attributable to the transition to autotrophic nutrition by the plant. At this stage, specific combining ability plays an important role in the total genetic variation. It is concluded that differing genetic controls exist in early and late material, and that this difference is also manifested in leaf initiation and elongation rates. The ground coverage rate, as a component of plant development, is genetically correlated to total dry matter yield. The genetic correlations vary according to the growth stage.
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  • 38
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; forage ; digestibility ; near infrared reflectance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Near infrared reflectance spectroscopy (NIRS) is emerging as a potentially useful tool in breeding plants for quality traits. Information is lacking, however, on its use in forage maize (Zea mays L.). The objectives of the present investigation were to evaluate the prediction of digestibility traits of maize stover using NIRS technique and to study the effect of laboratory (Lab) and NIRS assays on the estimates of variation and covariation. Twelve inbred lines, 66 diallel crosses among them and eight hybrid checks were evaluated at silage and grain harvests for 2 years at two agro-climatically diverse locations in the Federal Republic of Germany. Standard methods were used for Lab analysis of in vitro digestible organic matter (IVDOM), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). In NIRS evaluation, calibration equations were developed by modified stepwise regression. The standard error of calibration was 2.5, 1.7, 1.4 and 0.4 for IVDOM, NDF, ADF and ADL, respectively. The coefficient of multiple determination was high (≥0.9) except for ADL. The validation statistics (standard error and correlation coefficient) were similar. In the diallel crosses, the estimates of variation (heritabilities in broad and narrow sense, genotypic and error coefficients of variation), generally, did not vary appreciably and consistently in the comparisons between Lab and NIRS methods particulary at silage harvest. Simple and rank correlations between Lab and NIRS analyses were positive and significant. These correlation coefficients based on the mean performance of the diallel crosses at silage harvest were 〉0.9 and at least 16 hybrids were common between the two analyses, among the upper one-third or lower one-third (22) hybrids. The study showed that NIRS analysis should be useful in maize breeding programmes wherein a large number of genotypes need to be evaluated.
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  • 39
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    Euphytica 48 (1990), S. 63-72 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; corn ; yield ; kernel weight ; shelling percentage ; plant height ; ear height ; husk weight ; cob weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary White-endosperm (y y y) maize (Zea mays L.) is vital to the maize dry-milling industry. However, a substantially greater acreage in the U.S.A. is planted to yellow (Y Y Y) than white maize. Data on comparative performance of yellow and white maize is scanty, and results are inconclusive. This field study was conducted to provide information on dosage effects of y gene on grain yield, 500-kernel (K) weight, shelling percentage, plant and ear height, and cob weight. Yellow x yellow, yellow x white, and white x white endosperm crosses were made among five yellow and five white endosperm lines of Mo14W × Oh7B parentage. In the material studied, the genetic complement of the white-endosperm parent Mo14W varied from 12.50% to 87.50% across 15 treatments. The effect of Mo14W dosages among treatments was removed through analysis of covariance. If differences among treatment means existed, they were attributed to the y gene. A test of parallelism among regression coefficients (Ho. β1=β2=---β15=βc) indicated that these regressions coefficients for plant height, ear height, 500-K weight, and husk weight showed parallelism across yellow x yellow, yellow x white, and white x white crosses. Differences in plant height were significant in 3 out of 5 comparisons each between Y Y vs. y y, Y y vs. y y, and Y Y vs. Y y. Differences in ear height were significant in 1 of 5 Y Y vs. y y comparisons, in 3 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. Differences in 500-K weight were significant in 4 of 5 Y Y vs. y y, in 2 of 5 Y Y vs. Y y and in 1 of 5 Y y vs. y y comparisons. Differences in husk weight were significant in all the Y Y vs. y y comparisons, in 4 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. An increase in the y gene dosage caused, in general, a significant decrease in grain yield, 500-K weight, plant height, ear height, and husk weight. Shelling percentage was decreased but not appreciably. The Y y combination had a heterotic effect on plant height, ear height, and cob weight. An implication of the findings of this study is that it would be difficult to breed for high-yielding white maize if one used this y gene source. At this time, this is the only source (chromosome 6) available for white-endosperm maize. Non-parrallelism among regression coefficients was noted for shelling percentage, grain yield, and cob weight. Non-parallelism was observed in shelling percentage of the yellow x yellow crosses, cob weight of the yellow x white crosses and in grain yield of both yellow x yellow and yellow x white crosses. In general, an increase in mean Mo14W dosage resulted in increased grain yield. Mo14W dosages generally reduced cob weight in the yellow x white crosses. Shelling percentage increased as the mean Mo14W dosages increased for the yellow x yellow crosses. An increase in Mo14W dosages resulted in an increase in 500-K weight.
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  • 40
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    Plant and soil 122 (1990), S. 107-114 
    ISSN: 1573-5036
    Keywords: aseptic ; 14C-labelled ; carbohydrate ; decomposition ; root exudate ; maize ; monosaccharides ; root lysate ; sandy loam sonication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays var. Caldera) plants were grown under sterile and not sterile conditions in soil in an atmosphere continuously enriched with14CO2 for 36 days. At harvest the above ground parts of the maize were cut off and the roots were separated from the soil by washing with water. The soil was dispersed using ultrasonics and separated into soluble clay silt and sand fraction. Roots were included in the coarse sand fraction. 25% of the total label present in the soil ≡ 5.5% of that in the soil-plant system, was water soluble. Very little label was present in the clay and silt fractions (5% in each) and most (65%) was in the sand fraction as root material. Rapid extraction of soil after the removal of roots without ultrasonic treatment released soluble matter which amounted to 〈0.5% of the total activity in the soil-plant system. Isolated roots steeped in water released about 18% of their activity. Much of the soluble fraction may therefore be root lysate. The soil and roots accounted for 22% of the total activity in the soil-plant system. Glucose accounted for 89% of the sugars in the soluble fraction of the soil. 78% or more of the14C present in glucose, arabinose and xylose constituents of the root-soil mixture occurred in the coarse and fine sand fractions, which also included root material. For mannose and galactose the value was 70% and for rhamnose, 50%. After reinoculation of the soil-root mixture and decomposition for 56 weeks, the water soluble material obtained on fractionation of the soil decreased to less than 1% of the total activity. A much greater proportion, 25%, was present in the clay fraction as a result of decomposition.
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  • 41
    ISSN: 1573-5036
    Keywords: buried bag incubation ; leguminous green manures ; maize ; N mineralization ; N supplying potential ; N uptake ; Oxisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A buried bag incubation technique was proposed to monitor N release from soil and decomposing green manure. The technique would facilitate not only the screening of legumes as sources of N but also measurement of the N supplying capacity of soils. Several tropical legumes were incorporated into field plots followed either by maize (Zea mays L.) or by bare fallow. Soil samples from the plow layer containing the incorporated green manure were placed in low density polyethylene bags and buried within the plow layer under the maize crop for in situ incubation. Periodic withdrawal of the bags was accompanied by fallow soil profile sampling. Above ground N accumulation by maize was equally well correlated to N release measured by either method although the bag technique required much less labor. Supplemental experiments suggested that N accumulation in the bags was reduced due to inadequate O2 diffusion but only when O2 demand was high and soil water potential was high. The results show that in situ bag incubation alone or together with fallow soil sampling can be used to estimate the N supplying potential of soil and leguminous residues.
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  • 42
    ISSN: 1573-5036
    Keywords: alley cropping ; beans ; Erythrina ; Gliricidia ; humid tropics ; isotopically exchangeable P ; maize ; mulching ; phosphorus cycle ; P desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools. In the bioassay, P uptake of beans declined in the order: mulched sole-cropped〉unmulched sole-cropped〉alley-cropped soils. For maize the relative uptake was: mulched sole-cropped〉unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils. Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.
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  • 43
    ISSN: 1573-5036
    Keywords: fertilizer trials ; Kenya ; maize ; Striga hermonthica ; sunflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The adverse effect of the parasitic weed Striga hermonthica on yield of maize was studied in a fertilizer trial in Southwestern Kenya. In two years of experimentation (1987 and 1988), the weed had a highly significant, negative impact on maize yields. The spotty incidence of Striga disturbed the fertilizer trials. Inclusion of the degree of Striga infestation in a regression model caused an increase in the fraction of experimental variation that could be explained by the model. Several methods were tested to combat Striga. Hand-pulling reduced Striga incidence and increased grain yields during the following growing season. No clear effect was obtained from the trap crop sunflower, although such an effect may have been concealed by the success of hand-pulling. Application of mineral fertilizers or farmyard manure did not significantly reduce Striga infestation.
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  • 44
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    Plant and soil 138 (1991), S. 139-142 
    ISSN: 1573-5036
    Keywords: maize ; manganese deficiency ; pollen viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays L. cv. G2) was grown with 0.55 mg L−1 (sufficient), or 0.0055 mg L−1 (deficient) manganese in sand. Manganese-deficient plants developed visible deficiency symptoms and showed poor tasseling and delayed anther development. Compared to Mn-sufficient plants, Mn-deficient plants produced fewer and smaller pollen grains with reduced cytoplasmic contents. Manganese deficiency reduced in vitro germination of pollen grains significantly. Ovule fertility was not significantly affected by Mn. But in Mn-deficient plants seed-setting and development was reduced significantly.
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  • 45
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    Plant and soil 123 (1990), S. 83-88 
    ISSN: 1573-5036
    Keywords: maize ; nitrogen availability tests ; soil nitrate ; UV absorbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The ability of several chemical soil N availability indexes to predict the N supplying capability (NSC) of soils to maize in the field was evaluated in 49 field experiments over 3 years in Pennsylvania. Two recently proposed indexes based on the amount of NH4 + released by treating soil with 2 M KCl at 100°C for 4 hr or with a pH 11.2 phosphate-borate buffer for 8 min were not good predictors of NSC (r=0.484 and 0.254, respectively). The absorbance of a 0.01 M NaHCO3 extract at 260 nm was also poorly correlated with field-measured NSC (r=0.412). The pre-sidedress soil NO3 − test (PSNT), the soil NO3 − concertration in the surface 20 cm of soil at planting, and the UV absorbance at 200 nm of a 0.01 M NaHCO3 extract of at planting soils were all moderately well correlated with NSC (r=0.672, 0.750, and 0.737, respectively). The latter two indexes are very simple, rapid, and inexpensive to perform and offer the possibility of improving the prediction of NSC in heavily manured fields.
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  • 46
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    Plant and soil 123 (1990), S. 95-100 
    ISSN: 1573-5036
    Keywords: Belonolaimus longicaudatus ; Criconemella sphaerocephala ; maize ; Meloidogyne incognita ; nematode ; Paratrichodorus minor ; plant-parasitic nematodes ; Pratylenchus brachyurus ; sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Distribution of plant-parasitic nematode species at soil depths of 0–15 cm, 15–30 cm, and 30–45 cm was examined in two maize fields in Florida during 1987 and 1988. Soil type in both fields was an Arredondo fine sand, consisting of 94–96% sand at all three depths. On most sampling dates, more than 50% of the Belonolaimus longicaudatus collected occurred at the 0–15 cm depth. Only 20–30% of Criconemella sphaerocephala were present at this depth, and the depth distribution of this nematode differed in the two fields. The greatest densities of Pratylenchus brachyurus often occurred at 15–30 cm. Vertical distributions of Meloidogyne incognita and Paratrichodorus minor were erratic and showed marked seasonal variation. For all species examined except B. longicaudatus, a diagnostic soil sample collected 15 cm deep would recover only a minority of the nematode population present in the soil profile.
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  • 47
    ISSN: 1573-5036
    Keywords: barley ; chlorosis resistance ; cucumber ; genotypical differences ; grasses ; iron mobilization ; iron uptake ; maize ; microorganisms ; oat ; phytosiderophores ; rice ; root exudates ; root growth ; rye ; sorghum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Graminaceous species can enhance iron (Fe) acquisition from sparingly soluble inorganic Fe(III) compounds by release of phytosiderophores (PS) which mobilize Fe(III) by chelation. In most graminaceous species Fe deficiency increases the rate of PS release from roots by a factor of 10–20, but in some species, for example sorghum, this increase is much less. The chemical nature of PS can differ between species and even cultivars. The various PS are similarly effective as the microbial siderophore Desferal (ferrioxamine B methane sulfonate) in mobilizing Fe(III) from a calcareous soil. Under the same conditions the synthetic chelator DTPA (diaethylenetriamine pentaacetic acid) is ineffective. The rate of Fe(III)PS uptake by roots of graminaceous species increases by a factor of about 5 under Fe deficiency. In contrast, uptake of Fe from both synthetic and microbial Fe(III) chelates is much lower and not affected by the Fe nutritional status of the plants. This indicates that in graminaceous species under Fe deficiency a specific uptake system for FePS is activated. In contrast, the specific uptake system for FePS is absent in dicots. In a given graminaceous species the uptake rates of the various FePS are similar, but vary between species by a factor of upto 3. In sorghum, despite the low rate of PS release, the rate of FePS uptake is particularly high. The results indicate that release of PS and subsequent uptake of FePS are under different genetic control. The high susceptibility of sorghum to Fe deficiency (‘lime-chlorosis’) is most probably caused by low rates of PS release in the early seedling stage. Therefore in sorghum, and presumably other graminaceous species also, an increase in resistance to ‘lime chlorosis’ could be best achieved by breeding for cultivars with high rates of PS release. In corresponding screening procedures attention should be paid to the effects of iron nutritional status and daytime on PS release as well as on rapid microbial degradation of PS.
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  • 48
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    Plant and soil 123 (1990), S. 181-183 
    ISSN: 1573-5036
    Keywords: maize ; sterols ; sulphate uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data of compartmental analysis of sulphate were compared with the sterol content of roots of differently yielding maize genotypes. In conditions of steady state nutrient supply, sterol content was significantly correlated only with sulphate efflux (ϕco). This increased at increasing concentration of sterols in the roots. Influx to cytoplasm (ϕoc) was evaluated after sulphate deprivation leading to an induced rate of sulphate uptake. This was negatively correlated with sterol content, which was lower in the high than in the low yielding genotypes. When the highest yield genotype was grown at different sulphate concentrations, influx, efflux, root content of sulphate and sterols were positively correlated with the concentration of sulphate in the nutrient medium. Sterol content in roots appears to be controlled by both the genetic settlement and the nutritional status in maize. Low sterol content is connected with a high efficiency of sulphate utilization.
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  • 49
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    Plant and soil 134 (1991), S. 127-135 
    ISSN: 1573-5036
    Keywords: aluminium and acid saturation ; exchangeable aluminium and acidity ; lime requirement indices ; maize ; relative crop yields ; seasonal effects ; soil pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Due, in part, to the relative paucity of published comparisons based on field generated data, there is still poor agreement regarding the relative merits of lime requirement indices based on exchangeable Al and those based on pH. The objective of this study was to compare such indices using results obtained from long-term field experiments. Data were obtained over 22 site-years from lime trials conducted on clay (Typic Haplorthox) and sandy loam (Plinthic Paleudult) soils differing widely in organic carbon content. Relative maize (Zea mays L.) yields were used to compare the prognostic value of soil pH with indices obtained using exchangeable Al and exchangeable acidity (Al+H). Both within and across soils, pH proved to be markedly inferior to Al based indices. Exchangeable acid saturation of the effective cation exchange capacity, a readily obtained and popular index of lime requirement in some countries, proved as effective as less easily acquired indices based on exchangeable Al per se. The findings reported are consistent with those of many glasshouse studies and support the viewpoint that indices based on Al or acid saturation should replace pH as a measure of lime requirement.
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  • 50
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    Plant and soil 134 (1991), S. 277-280 
    ISSN: 1573-5036
    Keywords: bleeding rate ; maize ; root pruning ; root-study methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Current methods of studying roots are either labour intensive or require expensive equipment. In 1986 and 1987 root pruning treatments were given to maize plants grown indoors. In both years the amount of xylem exudate collected from plant stumps shortly after root pruning increased with the dry weight of roots attached to the plant. The measurement of xylem exudation is presented as an alternative for conventional laborious root-study methods.
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  • 51
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    Plant and soil 135 (1991), S. 213-221 
    ISSN: 1573-5036
    Keywords: maize ; plant growth-regulating substances ; plant hormones ; substrate dependend-cytokinin production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Glasshouse experiments were conducted to evaluate the influence of pretested cytokinin precursors, adenine (ADE) and isopentyl alcohol (IA), and a cytokinin producing bacterium, Azotobacter chroococcum added to soil, on the vegetative growth of maize (Zea mays L.). The combination of 2.0 mg ADE kg-1 soil, 13 mg IA kg-1 soil, plus an inoculum of A. chroococcum was the most effective in enhancing the vegetative growth of maize compared with the application of ADE plus IA, ADE plus A. chroococcum, or ADE, IA or A. chroococcum alone. The dry weight of root and shoot tissues was increased up to 5.57- and 5.01-fold, respectively, in comparison to the controls; however, the root/shoot ratios were similar. The increases in shoot height, internodal distance, stem and leaf width over the controls under the optimum treatment were: 2.07-, 2.81-, 1.46-, and 2.11-fold, respectively. The improvement in plant yield was primarily attributed to A. chroococcum production of cytokinins in the rhizosphere.
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  • 52
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    Plant and soil 138 (1991), S. 189-194 
    ISSN: 1573-5036
    Keywords: aggregate size ; carbon allocation ; maize ; shoot-root ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Shoot dry mass and leaf area of 16-d old maize plants decreased as soil aggregate size in greenhouse pots increased in diameter from 0.075–0.5 to 4–8 mm. Root length was also much greater on the finer aggregate beds, due primarily to increased growth of second-order laterals. In a subsequent experiment in which shoot dry matter again decreased with increasing aggregate size, it was found that a similar change in root morphology as noted in experiment I resulted in increased root dry mass as aggregate size increased. The associated change in shoot-root ratio was significant eight days after emergence. This change was due to a change in allocation of fixed carbon rather than allocation of seed reserves. Neither transpiration rate per unit leaf area, nor net assimilation rate were affected by aggregate size. Likewise nutrition could not account for the differences in shoot or root growth.
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  • 53
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    Euphytica 45 (1990), S. 131-137 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; acetochlor ; heterosis ; susceptibility ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The variation of response to acetochlor was studied in a two-year experiment carried out by subjecting 18 maize (Zea mays L.) inbred lines to three herbicide rates (0, 2.5 and 5 l a.i./ha). In both years some inbred lines consistently exhibited an evident susceptibility, with symptoms consisting of the seedling curling up below the soil surface and causing impaired field emergence. The results were poor plant density and lower grain yield in comparison to control. In contrast, other lines showed a satisfactory level of tolerance. Then, to gather data on the inheritance of response to acetochlor, four tolerant inbreds (T) and four susceptible inbreds (S) were crossed to obtain four T×T, four S×S, four S×T and the corresponding four T×S two-way hybrids. These hybrids were studied together with parental lines by applying the same herbicide rates used in the previous trial. The S×S hybrids showed susceptibility to the herbicide and the T×T were tolerant, whereas the S×T and the T× S hybrids showed a tolerance very close to that of the T×T hybrids. No difference was found between S×T and the corresponding T×S hybrids as to herbicide response. On average, the 16 hybrids exhibited greater tolerance than the eight parental lines, with each hybrid group being more tolerant than its parental line group. These results indicate that tolerance to acetochlor is prevailingly dominant, that action of extranuclear genes should be ruled out, and that the level of plant vigour can affect herbicide reactiveness.
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  • 54
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; Ostrinia nubilalis ; European corn borer ; resistance ; taxonomy ; germplasm ; indigenous land races
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The resistance to the European corn borer, Ostrinia nubilalis (Hubner), of thirty-seven indigenous landraces of Mexican maize was examined. The relationship of resistance and existing taxonomy of maize according to Wellhausen et al., (1952), was subjected to numerical analyses. Variables examined were: seedling DIM-BOA content, the extent of leaf feeding damage by early instar larvae both in the field and in the laboratory, the extent of plant breakage and stalk tunneling by late instar larvae, plant height, and the extent of fungal damage by Gibberella zeae and Ustilago maydis. Significant differences in resistance among the major taxonomic groupings were reflected in the existing taxonomy of maize (Wellhausen et al., 1952). The most resistant landrace grouping was Wellhausen et al.'s Prehistoric Mestizos. Eighty-five percent of a series of modern inbred lines, pools, and Argentine landraces were found to have affinities with one of the more susceptible groupings, the Ancient Indigenous Races, based upon analysis of the resistance data.
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  • 55
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    Euphytica 51 (1990), S. 19-23 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; corn ; Aspergillus flavus ; Aspergillus parasiticus ; aflatoxin ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Contamination of maize (Zea mays L.) grain prior to harvest with aflatoxin frequently occurs in the southern U.S.A. and sources of resistance are needed. Maize from twelve genotypes (varieties) crossed to two testers was analyzed for aflatoxin B1 (AFB1) contamination at Baton Rouge, LA and Tifton, GA in 1987. Variety Philippines had the lowest amount of AFB1 at Baton Rouge and one of the lowest amount of AFB1 at Tifton. In the combined analysis of variance, the location x treatment x tester x variety interaction was significant. This interaction was analyzed and a stability variance (σ1 2) statistic calculated. Mean AFB1 accumulation and stability of AFB1 production were examined simultaneously, i.e., variety ranks for AFB1 and σ1 2 were summed. The most desirable (lowest rank sum) variety across locations, testers, and treatments (inoculation and control) was St. Charles White, followed by Delta Prolific White, and Hopi. The most inconsistent AFB1 accumulation, along with high AFB1, was on Fino, Atkinson, USAWI, Navajo, and Michoacan-21. The ranks of varieties between the inoculation and control treatments were different (rs=−0.51 for Baton Rouge and 0.29 for Tifton). The rs (rank correlation coefficient) for the control treatments between Baton Rouge and Tifton was 0.60 (P〈0.05) and that for the inoculation treatments was −0.20. The varieties identified in this study as having relatively low concentration of AFB1 should be useful to maize breeders in reducing AFB1 contamination in field maize.
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  • 56
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; genetic variation ; nitrate accumulation ; N use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The objective of this research was to obtain information about expression of genes controlling N concentration in the lower stalk internodes of maize at silking stages and in two other stages during the grain filling period. The inheritance of nitrate-N concentration, total N concentration, and the nitrate-N/total N ratio in the lower stalk internodes was measured in an eight-line diallel cross experiment and in an experiment involving segregating generations. The results show that the parameters examined, particularly nitrate-N concentration, are genetically controlled and that maize plants differ in this respect. Moreover, the magnitude of the general combining ability effects in relation to the size of specific combining ability obtained from the diallel analysis and the mean squares of the analysis of variance of generation means indicated additive heritability of nitrate-N concentration and other N-related traits in maize stalks. These findings suggest to us that a cyclic selection program in maize should be effective in modifying the level of N-related traits concentration in the stalks.
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  • 57
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; prediction ability ; discrimination ability ; yield ; digestibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The identification of environments suitable for selection should enable plant breeders to test reliably a larger number of genotypes with given resources. This research was undertaken to evaluate discrimination ability (DA) and prediction ability (PA) of eight environments involving two locations. Eckartsweier (Eck) 1 and Voelkenrode (Voe); 2 yer. 1984 (84) and 1985 (85); and two harvests, silage harvest (I) and later (II). It was based on dry matter yield of plant (PDMY), ear (EDMY) and stover (SDMY) and on in vitro digestible organic matter (IVDOM), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) of stover of 12 inbred lines and their 66 diallel crosses in maize (Zea mays L.). Linear regression coefficient of the performance of genotypes in an environment on that averaged across all environments and its degree of determination were used as measures of the DA and PA of environments, respectively. In hybrids, the DA of environments differed significantly for all traits except SDMY and ADL. Environment Eck851 showed better PA (≥0.63) than other environments for PDMY, EDMY, IVDOM, NDF, and ADF. Among the 12 two-environment combinations. EckI was a better predictor for PDMY, EDMY, IVDOM and NDF (PA≥0.80). The more productive environments showed better DA and PA for PDMY and FDMY than less productive ones. For IVDOM and NDF the first harvest provided better discrimination and prediction than the second harvest. In inbred lines the DA of environments differed significantly for EDMY only. In the present study, PA and DA seemed to be functions of the environments, PA was improved by combining two environments, and some environments seemed to be suitable for preliminary selection of genotypes for such diverse traits as yield and digestibility.
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  • 58
    ISSN: 1573-5036
    Keywords: Cmin ; depletion curve ; flowing solution culture ; Glycine max L. ; Imax ; Km ; maize ; phosphate uptake kinetics ; soybean ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To obtain plants of different P status, maize and soybean seedlings were grown for several weeks in flowing nutrient solution culture with P concentrations ranging from 0.03–100 µmol P L-1 kept constant within treatments. P uptake kinetics of the roots were then determined with intact plants in short-term experiments by monitoring P depletion of a 3.5 L volume of nutrient solution in contact with the roots. Results show maximum influx, Imax, 5-fold higher in plants which had been raised in solution of low compared with high P concentration. Because P concentrations in the plants were increased with increase in external P concentration, Imax was negatively related to % P in shoots. Michaelis constants, Km, were also increased with increased pretreatment P concentration, only slightly with soybean, but by a factor of 3 with maize. The minimum P concentration, Cmin, where net influx equals zero, was found between 0.06 and 0.3 µmol L-1 with a tendency to increase with pretreatment P concentration. Filtration of solutions at the end of the depletion experiment showed that part of the external P was associated with solid particles. It was concluded that plants markedly adapt P uptake kinetics to their P status, essentially by the increase of Imax, when internal P concentration decreases. Changes of Km and Cmin were of minor importance.
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    Nutrient cycling in agroecosystems 30 (1991), S. 39-46 
    ISSN: 1573-0867
    Keywords: Rock phosphate ; single superphosphate ; P uptake ; VAM fungi ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of inoculation with fourteen endomycorrhizal species belonging to the generaGigaspora, Scutellospora, Glomus, Acaulospora andEntrophospora on the growth of maize (Zea mays L.) was evaluated under glasshouse conditions in an unsterilized tropical virgin soil using two P sources with different solubility. In both P treatments the population of indigenous mycorrhiza species was not affected and growth of maize was enhanced. Introducing VAM species additionally modified the growth pattern of maize. Using a low-grade rock phosphate (Patos de Minas) from Brazil all endophytes with exception ofGigaspora margarita, Scutellospora verrucosa, Scutellospora gregaria, Entrophospora colombiana andGlomus pallidum improved shoot dry weight. In the treatment with single superphosphate, dry matter production was not significantly enhanced byGigaspora margarita, Gigaspora gigantea, Scutellospora verrucosa, Scutellospora reticulata, Scutellospora gilmorei andGlomus manihotis. When rock phosphate was added root fresh weights were enhanced only by three endophytes (Gigaspora margarita, Gigaspora gigantea andAcaulospora rehmii); with single superphosphate none had a significant effect. The percentage of P in shoots was almost equal in non-inoculated and inoculated plants and yield responses did not always follow the pattern of P uptake. Mycorrhizal root infection was always highest in the treatment with single superphosphate and in most cases a correlation with plant growth was found. The present results show that introduced vesicular arbuscular mycorrhiza species differently promote growth of maize according to their adaptability to the P source and to their capability to compete with native VAM endophytes.
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    Agroforestry systems 14 (1991), S. 193-205 
    ISSN: 1572-9680
    Keywords: Acacia albida ; intercropping ; maize ; green gram ; coastal lowlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long-term agroforestry demonstrations/trials using Acacia albida and other nitrogen fixing multipurpose trees/shrubs were initiated in mid-1982 to assess soil and crop productivity at a coastal lowland site characterized by low soil fertility, weed problems and consequent poor crop yields. Growth performance (height and diameter at breast height, dbh) of Acacia albida under eight densities rotationally intercropped with maize (Zea mays) and green gram (Phaseolus aureus), crop grain yields, soil fertility changes and weed control were assessed for a 5-year period (May 1982 to March 1987). A parallel-row systematic spacing field layout was used. Intercropped Acacia albida mean hight and dbh were 140 and 24% respectively higher than tree-only controls by the fifth year. Growth rate was low during the first year but increased in subsequent years to mean height and dbh of 9 m and 10 cm respectively by March 1987. While differences in dbh were significant, those between stand heights were not. Crop yields, especially under higher tree densities, declined considerably due to unexpected shade which also caused significant reductions in weed biomass. Soil fertility levels remained unchanged during the experimental period relative to the initial status, and differences between the intercropped Acacia albida plots and the tree — or crop — only control appeared not to be significant. We conclude that an understanding of the mechanism regulating leaf fall/retention phenomena of Acacia albida is crucial towards determining the intercropping potentials of the species.
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    Agroforestry systems 10 (1990), S. 169-181 
    ISSN: 1572-9680
    Keywords: Alley cropping ; highland agroforestry ; maize ; pole bean ; Sesbania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Food production in the densely populated Rwandan highlands is impeded by soil erosion and loss in fertility. Alley cropping leguminous shrubs with food crops on contours is purported to minimize the problem and to provide wood and forage. This study reports the effect of Sesbania prunings plus moderate levels of N and P on bean (Phaseolus sp) and maize (Zea mays) yields in alley cropping. Experimental design was a randomized complete block with split-split plots. Main plots were alley width: 2, 4, 6 and 8 m. Phosphorus (P) at 0, 30 and 60 kg P2O5/ha occupied the subplot and nitrogen (N) at 0, 30 and 60 kg/ha were assigned at the sub-sub plot level. No P was applied to maize during the second cropping season. Crop yield in kg/ha included the land space taken by hedgerows. Bean yield in 6 m alleys (1100 kg/ha) was about twice that in 2 m alleys (500 kg/ha). Bean responded to N and P. Optimum alley width and N for bean yield were 6 m and 30 kg/ha, respectively. Cuttings from alley hedgerows provided stakes for climbing beans. Maize responded to N but not to residual P. The highest maize yield came from 8 m alleys with 40 kg/ha, but yields from 8 and 6 m alleys with the same N treatment were not significantly different. Maize plants in middle rows were significantly taller than plants in rows adjacent to hedgerows. Maize rust development showed significant alley width and row position effect. There were significantly fewer uredinia in the Sebania alleys relative to the control plots without shrub hedgerows. Rust development on maize in middle rows was significantly greater than development in border rows.
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  • 62
    ISSN: 1572-9680
    Keywords: Agroforestry ; green manure ; leucaena ; sesbania ; pigeonpea ; soil fertility ; maize ; beans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three multipurpose tree species (MPTS)-leucaena (Leucaena leucocephala), sesbania (Sesbania sesban var. nubica) and pigeonpea (Cajanus cajan) were pruned at a height of 60 cm above the ground every two months, and resulting plant biomass was incorporated into the soil as green manure. For comparison, maize (Zea mays) stover was also incorporated into some plots, while some other plots were left fallow. Varying quantities of plant biomass which were incorporated into the soil over a period of 12 months caused large changes in major soil plant nutrients, and it substantially improved soil fertility. To test for improved soil fertility, test crops of maize and beans (Phaseolus vulgaris) were grown on the plots after six biomass incorporations of 4806, 13603, 16659 and 7793 kg. ha−1yr−1 for pigeonpea, sesbania leucaena and maize, respectively. Responses of the test crops indicated that sesbania and leucaena green manures improved maize stover, cobs and grain yields; and bean haulms and grain yields by 77.6% when compared to fallow plots. Residual effects of green manures still resulted in significant (P 〈 0.05) yield differences in the test cropin the third testing season. Economic significance of green manures in increasing food crop yields to small scale farmers is discussed.
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  • 63
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    Human ecology 19 (1991), S. 389-418 
    ISSN: 1572-9915
    Keywords: maize ; indigenous knowledge ; technological change ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This paper presents a case study of the relationship between farmers' knowledge of maize varieties and their selection and management of these varieties under conditions of technological change. Research for this paper was done among Spanish-speaking small farmers in an ejidoof central Chiapas, Mexico. This ejido is well integrated into the market, and the use of modem technologies is widespread. This research demonstrates that farmers have an extensive and widely shared knowledge of their maize varieties. This knowledge reflects objective maize characteristics. Variation occurs in the farmers' selection and management of maize varieties, but on average the variation deviates from a random pattern in the direction predicted by the farmers' knowledge base. They have incorporated the technological changes brought about by development into their knowledge base. Farmers maintain maize varieties with contrasting traits, and their knowledge base provides important information about which traits and constraints are important to them.
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    Photosynthesis research 25 (1990), S. 101-106 
    ISSN: 1573-5079
    Keywords: maize ; phosphoenolpyruvate carboxylase ; diethyl oxaloacetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diethyl oxaloacetate was found to be a competitive inhibitor of maize leaf phosphoenolpyruvate carboxylase activity with respect to the substrate phosphoenolpyruvate. The Ki values, based on total diethyl oxaloacetate, decreased with increasing pH, while the Ki values, based on the enol tautomer (average of 4 μM), were similar and independent of pH. The results suggest that inhibition is dependent on the enol tautomer. Diethyl oxaloacetate was a weak inhibitor following treatment of the enzyme with dithiothreitol; inhibition could be restored by treatment with diamide, indicating inhibition depends on the reduction state of thiol groups on the enzyme.
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    Plant and soil 121 (1990), S. 107-114 
    ISSN: 1573-5036
    Keywords: aseptic ; 14C-labelled ; carbohydrate ; decomposition ; root exudate ; maize ; monosaccharides ; root lysate ; sandy loam sonication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays var. Caldera) plants were grown under sterile and not sterile conditions in soil in an atmosphere continuously enriched with 14CO2 for 36 days. At harvest the above ground parts of the maize were cut off and the roots were separated from the soil by washing with water. The soil was dispersed using ultrasonics and separated into soluble clay silt and sand fraction. Roots were included in the coarse sand fraction. 25% of the total label present in the soil ≡ 5.5% of that in the soil-plant system, was water soluble. Very little label was present in the clay and silt fractions (5% in each) and most (65%) was in the sand fraction as root material. Rapid extraction of soil after the removal of roots without ultrasonic treatment released soluble matter which amounted to 〈0.5% of the total activity in the soil-plant system. Isolated roots steeped in water released about 18% of their activity. Much of the soluble fraction may therefore be root lysate. The soil and roots accounted for 22% of the total activity in the soil-plant system. Glucose accounted for 89% of the sugars in the soluble fraction of the soil. 78% or more of the 14C present in glucose, arabinose and xylose constituents of the root-soil mixture occurred in the coarse and fine sand fractions, which also included root material. For mannose and galactose the value was 70% and for rhamnose, 50%. After reinoculation of the soil-root mixture and decomposition for 56 weeks, the water soluble material obtained on fractionation of the soil decreased to less than 1% of the total activity. A much greater proportion, 25%, was present in the clay fraction as a result of decomposition.
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  • 66
    ISSN: 1573-5036
    Keywords: maize ; sorghum ; spore production ; VAM fungi ; water-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays) and sorghum (Sorghum bicolor) were inoculated with a range of VAM fungi and grown under water-stressed and unstressed conditions. There was considerable variation amongst the inocula in their effects on plant growth. Inoculation withGlomus clarum produced the biggest plants in each host, withGlomus monosporum andAcaulospora sp. giving the least growth overall. Root infection produced by the different inocula also varied, but levels were not correlated with effects on plant growth. Water-stress reduced plant growth, with the effects not being altered by mycorrhizal infection. VAM infection levels were not affected by water-stress. Spore production from most inocula was reduced by water-stress, both in total spore numbers and in terms of spores per gram plant weight. Sporulation ofG. clarum, G. epigeum andG. monosporum were affected less by stress than were the other inocula. Spore production was in general greater on sorghum than on maize, but the host effect varied amongst the inocula.
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  • 67
    ISSN: 1573-5036
    Keywords: calcareous soil ; copper ; hyphal transport ; iron ; maize ; manganese ; phosphorus ; VA-mycorrhiza ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An investigation was carried out to test whether the mechanism of increased zinc (Zn) uptake by mycorrhizal plants is similar to that of increased phosphorus (P) acquisition. Maize (Zea mays L.) was grown in pots containing sterilised calcareous soil either inoculated with a mycorrhizal fungus Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe or with a mixture of mycorrhizal fungi, or remaining non-inoculated as non-mycorrhizal control. The pots had three compartments, a central one for root growth and two outer ones for hyphal growth. The compartmentalization was done using a 30-μm nylon net. The root compartment received low or high levels of P (50 or 100 mg kg−1 soil) in combination with low or high levels of P and micronutrients (2 or 10 mg kg−1 Fe, Zn and Cu) in the hyphal compartments. Mycorrhizal fungus inoculation did not influence shoot dry weight, but reduced root dry weight when low P levels were supplied to the root compartment. Irrespective of the P levels in the root compartment, shoots and roots of mycorrhizal plants had on average 95 and 115% higher P concentrations, and 164 and 22% higher Zn concentrations, respectively, compared to non-mycorrhizal plants. These higher concentrations could be attributed to a substantial translocation of P and Zn from hyphal compartments to the plant via the mycorrhizal hyphae. Mycorrhizal inoculation also enhanced copper concentration in roots (135%) but not in shoots. In contrast, manganese (Mn) concentrations in shoots and roots of mycorrhizal plants were distinctly lower, especially in plants inoculated with the mixture of mycorrhizal fungi. The results demonstrate that VA mycorrhizal hyphae uptake and translocation to the host is an important component of increased acquisition of P and Zn by mycorrhizal plants. The minimal hyphae contribution (delivery by the hyphae from the outer compartments) to the total plant acquisition ranged from 13 to 20% for P and from 16 to 25% for Zn.
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  • 68
    ISSN: 1573-5036
    Keywords: Glycine max (L.) Merr. ; intercropping ; maize ; N-depleted soil ; 15N dilution method ; N transfer ; soybean ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1985, 1986 and 1988, maize (Zea mays L.) was monocropped or intercropped with nodulating or nonnodulating soybean (Glycine max [L.] Merr.). In addition, nodulating soybean and nonnodulating soybean were each monocropped and grown as a mixture. In 1985 and 1986, treatments were grown at 0 and 60 kg N ha−1 and in 1988, the treatments were grown without N fertilizer, on N-depeted soil and on non-N-depleted soil. 15N enriched N was applied to soil in all the aforementioned treatments to test for N transfer from nodulating soybean to non-N2-fixing crops by the 15N dilution method. The 15N dilution method did not show the occurrence of N transfer in 1985 and 1986, but the N sparing effect was evident from the total N uptake of nonnodulating soybean, dwarf maize and tall maize, in 1986. In 1988, maize and nonnodulating soybean seed yields and seed N yields were higher on non-N-depleted soil than on N-depleted soil. On N-depleted soil, the 15N dilution method indicated N transfer from nodulating soybean to maize and to nonndulating soybean. At a population ratio of 67% nodulating soybean to 33% nonnodulating soybean, N transfer was also seen on non-N-depleted soil in 1988.
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  • 69
    Electronic Resource
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    Plant and soil 132 (1991), S. 85-90 
    ISSN: 1573-5036
    Keywords: maize ; phosphate ; phosphatase ; roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The long-term response of hydroponically grown maize plants to variations in the phosphate concentration in the growth medium was studied. There was a 5-week lag period before any differences between experimental and control groups could be seen. After this period, the plants grown without phosphate devoted a higher percentage of their total mass to roots than did the controls. The roots of the phosphate-free plants were longer and less bushy than those of the control plants. Plants grown without phosphate showed an increase in the amount of acid phosphatase extractable from the external surfaces of the roots by a high salt solution. These phosphate stress responses were induced by 5 μM phosphate but not by 25 μM phosphate.
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  • 70
    ISSN: 1573-5060
    Keywords: corn ; maize ; Zea mays L. ; aflatoxin ; resistance ; lfy gene ; Aspergillus flavus ; Aspergillus parasiticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aspergillus flavus Link ex Fries spores are commonly used as inoculum for screening maize (Zea mays L.) genotypes for resistance to aflatoxin accumulation on grain. Occasionally, A. parasiticus Speare is also used for this purpose. However, only limited data are available on whether one species is as effective as the other for identifying aflatoxin-resistant genotypes. Our objective was to determine relative aflatoxin accumulation on kernels of maize containing the leafy (Lfy) gene in response to A. flavus and A. parasiticus. Aflatoxin production by A. flavus and A. parasiticus on grain of seven maize synthetics containing the Lfy gene, viz., A619, A632, Mo17, B73, HY, Wf9, and 914, was examined in three environments in Louisiana. Ears were doubly inoculated at 14 and 21 days after mid-silk by atomizing over external silks a 2 ml suspension containing 2.0×107 spores ml-1 of either A. flavus or A. parasiticus. All genotypes responded similarly in the three environments to both the fungal species. Aflatoxin B1 and B2 production did not differ in the three environments. The seven genotypes did not differ in levels of aflatoxin accumulation in response to either A. flavus or A. parasiticus. Aflatoxin production by A. flavus was detected in maize samples from all three environments, but aflatoxin production by A. parasiticus was found only in samples from Winnsboro, where moisture stress occurred. Mean B1 and B2 production by A. flavus from the three environments was, respectively, four and one-half times and two times more than that by A. parasiticus.
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  • 71
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    Plant cell, tissue and organ culture 23 (1990), S. 59-66 
    ISSN: 1573-5044
    Keywords: development ; ears ; maize ; maturation ; ovaries ; stamens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Observations were made on the maturation of stamens and ovaries from cultured maize (Zea mays L.) ear inflorescences. Immature ears (5.1–10.0 mm long) of maize were cultured in kinetin medium to study microsporogenesis and pollen maturation in developing stamens. Male spikelets developed on ears cultured in kinetin medium. Meiosis-I began by 7 days of culture in the developing anthers and the mature tri-nucleate pollen grains were developed by 20 days of culture. Further, kinetin was required in the culture medium for at least initial 5 days to obtain the microspores in differentiated stamens. To observe the embryosac formation in developed ovaries, ears were cultured in control, kinetin (10.1–15.0 mm long ears) medium, and kinetin + gibberellic acid (5.1–10.0 mm long ears) medium. Formation of embryosacs was noticed in the developed ovaries which were sampled after 20 days of culture. This differential flower development using two growth regulators provides an opportunity to uncover the biochemistry and physiology of micro- and mega-gametophyte development in maize.
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  • 72
    ISSN: 1573-1561
    Keywords: Phenolic acids ; resistance ; susceptibility ; maize ; maize weevil ; Sitophilus zeamais ; Coleoptera ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The (E)-ferulic acid content of the grain of nine populations of land races of maize derived from CIMMYT's collections was found to be negatively correlated to susceptibility characteristics towards the maize weevilSitophilus zeamais. Correlation coefficients for six susceptibility parameters and (E)-ferulic acid content were significant and ranged from −0.58 to −0.79. A multiple regression analysis by the SAS forward procedure using the primary seed characteristics associated with susceptibility indicated that the ferulic acid content was the only significant factor in explaining variation in at least two susceptibility parameters: the Dobie index and adult preference. In 15 CIMMYT pools, correlations between four susceptibility parameters and (E)-ferulic acid content were also significant (−0.76 to −0.81). The results suggest that phenolic acid content is a leading indicator of grain resistance or susceptibility to insects and may represent a newly identified mechanism of resistance.
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  • 73
    ISSN: 1573-8248
    Keywords: Sesamid ; Platytelenomus ; egg parasitoid ; maize ; sex ratio ; parasitism ; Sesamia ; Platytelenomus ; maïs ; parasitoides oophages ; sex ratio ; parasitisme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le parasitoïde scelionid,Platytelenomus busseolae, a été recueilli des ooplaques de la sésamie dans la région d'Istiaea, en Grèce Centrale. Le parasitisme naturel a été étudié pendant les années 1986 et 1987. Un nombre de 3 382 ooplaques avec un total de 205 227 œufs ont été recueillis. Les premiers œufs parasitisés ont été récoltés fin-juillet, début-août et les derniers à la mi-octobre. En 1986, 76,2% des ooplaques et 42,8% des œufs étaient parasitisés, mais en 1987 les valeurs respectives étaient 27,6% et 12,9%. L'activité moindre du parasitoïde en 1987 serait due aux conditions climatiques hivernales et estivales. En 1987, la sex ratio, femalle: mâle, a été 1,5: 1 et 26,2% des ooplaques seulement ont donné naissance à des ♂♂. Les ♀♀ fécondées ont produit 3 fois plus de ♀♀ que de ♂♂. Dans des conditions climatiques favorables, le parasitoïde peut jouer un rôle important dans la lutte biologique contre la sésamie.
    Notes: Abstract The egg parasitoid,Platytelenomus busseolae (Gahan) (Hymenoptera: Scelionidae) was recorded from egg masses of the corn stalk borer,Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) on maize in the area of Istiaea, Central Greece. Natural parasitism was studied during the years 1986, 1987. A total of 3,382 egg masses, containing 205,227 eggs, was collected from corn fields. Parasitized eggs were found from end July to mid-October. In 1986. 76.2% of the egg masses and 42.8% of all eggs were parasitized, while in 1987, respective values were 27.6% and 12.9%. The inferior performance of the parasitoid in 1987 may be due to the unfavorable winter and summer conditions. Parasitism decreased when the host population was at its peak, but it increased again within 1 to 3 weeks. A small percentage of egg masses was completely parasitized (9.5% and 4.7% for the 2 years respectively). In 1987, the sex ratio, ♀♀/♂♂ was 1.5: 1 and 26.2% of the egg masses produced only ♂♂. Mated ♀♀ produced 3 times more ♀♀ than ♂♂. It seems that the parasitoid, under favorable weather conditions, can play a significant role in the control of the corn stalk borer.
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