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  • 1
    Publication Date: 1977-03-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 2
    Publication Date: 1960-02-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 3
    Publication Date: 1972-02-01
    Description: SUMMARYWork that has been reported from some African countries indicates a dependence of grain yield in maize on the duration of leaf area after flowering. This paper studies maize yield in south-east England and confirms work at a similar northern latitude in Canada which has shown that considerable remobilization of photosynthate from the stem to the ear takes place during the main ear fill period.A similar grain yield was obtained from two contrasting hybrids. In a short early hybrid, Kelvedon 75A, there was a low peak leaf area index (5·3) but the net assimilation rate was high due possibly to efficient light interception by leaves that maintained an erect posture. Stem dry matter was also low and hence in this hybrid the high reproductive/vegetative ratio shows that there has been economy in the production of leaves and stem, especially as a 48% stem loss occurred during the period of ear fill.In contrast, in a later hybrid, Anjou 210, the final shoot dry matter was 20% higher as the peak leaf-area index of 7·7 gave slightly higher crop growth rates than K 75A. Although the remobilization of stem dry matter was similar in both hybrids it was notable that a different partition of dry matter in the ears of Anjou 210 gave a higher grain/rachis ratio.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
    Publication Date: 1972-02-01
    Description: SUMMARYThree maize hybrids (Kelvedon 75A, Kelvedon 33, and Anjou 210) were grown under irrigated conditions at a wide range of density from 5·4 to 21·6 seeds/m2 at a rectangularity of 1:1. For yield of digestible dry matter at the time of silage harvest (7 October) a seed rate of 10·8 seeds/m2 (44000/acre) appeared adequate, as doubling the density to 21·6/m2 only resulted in 7% higher yield. K 33, which is a late·maturing hybrid bred for silage in south-east England (50·5–52·5 °N) produced the highest total yield of digestible dry matter due to a high yield of digestible stem. However, the dry matter % of this material would be too low for good ensilage and for a high level of feed intake. In the early grain hybrid K 75 A, 62% of the digestible dry matter was contained in the ear at the silage stage which improved the digestibility and dry matter % of the whole crop with only a 12% lower yield than K 33.The optimum density for grain was 10·8 seeds/m2. This is a higher response to density than is believed to occur in field crops in Britain as in these experiments the seed was planted on the square and irrigation was applied at moisture sensitive stages. The parabolic relationship between grain yield and density was closely related to grain number per unit area. At 10·8 seeds/m2 all three hybrids were of similar yield and grain number per unit area. In Anjou 210 this was achieved with one large ear per plant, whilst for the two Kelvedon hybrids mean ear production was 1·34/plant but with 27% fewer grains per ear.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
    Publication Date: 1974-12-01
    Description: SummaryThree field experiments are described in which the effect of plant density and date of stopping (removal of the apical bud) on the development of yield in several Brussels sprout cultivars was studied. In a fourth experiment, the effect of a leaf removal treatment was designed to assess the possible remobilization of dry matter to the buds from senescing leaves.A total plant dry weight of 1·2 kg/m2 was achieved with a hybrid cultivar at commercial densities. Although the crop growth rate was low in midsummer, growth continued until mid-October. Bud dry weight yield was curvilinearly related to plant density with 2 plants/m2 giving the highest yields of 0·35 kg/m2 in stopped crops in November. Rapid bud growth did not begin until September but the increase in bud dry weight continued into December and January. Early stopping increased bud dry weight yield and the ratio of bud weight to total shoot weight. In November, bud dry weight accounted for 25–40% of the total shoot dry weight for most treatments.In the leaf removal experiment, estimated net photosynthetic rate of the crop was greater than the bud growth rate up to the end of the experiment and there was no significant effect of removing leaves just prior to natural senescence on bud dry weight.The production and partition of dry matter is discussed in comparison with other vegetative crops. It is found that the proportion of total dry weight partitioned to the useful parts in Brussels sprouts is comparatively low. Factors controlling the date at which rapid bud growth begins are discussed. It is concluded that the dry matter in the axillary buds is derived from photosynthesis occurring at the time of bud growth and that the remobilization of dry matter from other plant parts is not of great importance.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
    Publication Date: 1970-04-01
    Description: SUMMARYYield and growth analysis has been carried out on vining peas (variety Dark Skinned Perfection) sown at 43, 97 and 172 seeds/m2 at a rectangularity of 1:1. No difference wasobtained in the yield of green peas (at tenderometer reading 110) over this fourfolddifferencein sowing density.At a high seed rate (172/m2) a high peak leaf area (8·3) was attained 1 week afterthe start of flowering but declined rapidly. The peak number of flowers and pods reached 1002/m2 at this density, but there was a greater wastage (34 %) by abscission than inthe lower seed rates which resulted in a similar number of pods/unit area being present at the time of vining for all densities.In contrast, peas sown at low density (43/m2) resulted in a lower peak leaf area (4·3) but this occurred during the stage of pod fill; net-assimilation rate was somewhat higher also. Thus the yield of green peas may depend less on the ability of the plant stand to provide reproductive nodes than on its ability to produce photosynthate during the post-flowering period.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
    Publication Date: 1971-08-01
    Description: SummaryWhen incoming radiation was reduced artificially to 50% daylight during the postflowering period in peas, the rate of abscission of flowers and pods increased in the same way as when the density of planting is raised. Shading from flowering onwards reduced yield almost to the level of peas that were shaded throughout the growing season, even though peas that received full daylight until flowering had many fertile tillers and a greater reproductive potential in terms of the total number of flowers produced. Conversely, when shades were removed at flowering time the crop was able to compensate and yields approached those of peas grown entirely in full daylight, this was mainly due to a reduction in absoission losses of flowers and pods so that the majority of pods formed on the main stem contributed to final yield.It is suggested from these results that the major source of dry matter for pea yield is the photosynthate produced during the post-flowering period rather than that translocated from roots or stems following storage during the vegetative period.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
    Publication Date: 1975-10-01
    Description: SUMMARYExperiments are described which analyse the effects of date of sowing and of a black petroleum soil mulch on the growth of two maize hybrids. The two hybrids used were Anjou 210, which is late maturing in S.E. England, and Kelvedon 75A, which is an early hybrid.As sowing was delayed from mid-April until the end of May, so there was a greater development of vegetative tissue (mainly stem) and leaf area which reached peaks at a later stage after silking. In Anjou 210 early sowing led to higher grain yields (12%) as the production of peak vegetative weight near to the time of silking allowed dry matter produced after that stage, still at a time of high radiation, to move direct to the oars. Also, the remobilization of the secondary source of grain dry matter, namely previously stored photosynthate from the stem, occurred earlier with early sowing and to a greater extent when a longer grain-filling period was allowed.The hybrid K 75A had a lower vegetative weight, and earlier silking coincided with higher levels of radiation, and the resultant increase in net assimilation rate led to a higher proportion of dry matter being partitioned into the ear. Because this hybrid flowered and senesced early, reserves of stem carbohydrate were low and the time available to transfer carbohydrate to the ear was short, resulting in lower yields than in the later maturing Anjou 210. K 75A also responded unexpectedly to the sowing treatments. Although late sowing gave higher grain yields in both hybrids up to 156 days after sowing, in the case of K 75 A, the early senescence curtailed the continuation of grain fill that would normally give early sowing an advantage and hence the late sown K 75 A produced 10 % more grain.The application of a black petroleum mulch to the surface of the soil to raise soil temperature enhanced the benefits derived from early sowing. Plants given this treatment produced greater leaf areas and vegetative dry weights. As a result more carbohydrate was translocated from the stem during the grain-filling period, increasing grain yield by 13% following an increase in both number of grains and individual grain weight.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
    Publication Date: 1976-08-01
    Description: SummaryThe growth and development of two varieties of Phaseolus vulgaris (Purley King and Limelight) were compared in two experiments in 1973 and 1974 at a range of planting density from 20 to 100 seeds/m2. Within this range, the relationship between seed yield and density in Purley King was asymptotic, although there was a suggestion that if even higher densities had been tested, a downward trend in yield might have occurred. The optimum density of planting for Purley King in Expt 1 was 50 seeds/m2 while that for Limelight was 40 seeds/m2. The corresponding densities in Expt 2 were 75 and 50 seeds/m2 respectively. Although number of branches per plant generally decreased with increasing density, there was no significant density effect on the number of nodes per plant. Thus stabilization of seed yield occurred even at quite low densities. Although in the low-density treatments, less vegetative tissue was produced, the peak of dry-matter yield occurred later after flowering and the slower subsequent senescence ensured the presence of active photosynthetic tissue throughout the pod-fill stage. Less pod retention occurred at high density which, combined with the ability of widely spaced plants to produce pods over a longer period, resulted in a similar number of pods per unit area over a wide range of density.Although the variety Purley King produced more than double the number of mature pods from its extra nodes and branches, it was outyielded by Limelight by 35% from the combined effect of more seeds per pod and a higher mean seed weight. Limelight also produced this high yield with less vegetative tissue. In both varieties it appeared that pod photosynthesis could take place, in Purley King because the pods were borne on higher nodes above the canopy and in Limelight due to the earlier senescence of its smaller leaf area. However, in spite of the apparent physiological advantages of Limelight, the pods are not borne high enough on this plant to enable satisfactory mechanical harvesting.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
    Publication Date: 1960-10-01
    Description: 1. Field experiments are described in which the absorption of radioactive strontium by rye-grass and lucerne has been investigated during 1958 on five soil types which represent a range in exchangeable soil calcium content. 89Sr was applied as a spray to both arable land and to established pasture.2. Absorption was reduced by a factor of up to 4 in rye-grass (shallow rooted) following ploughing to 11 in. compared with leaving the contamination on the soil surface. These results are compared with those obtained in an earlier series of experiments in 1957.3. The ratio of 89Sr to calcium was highest in crops grown on soil low in calcium (2 m-equiv. Ca per 100 g. extracted with N-ammonium acetate).4. The addition of lime reduced absorption of 89Sr from the soil only when the exchangeable soil calcium content was relatively low. Some effect was observed in soils containing 7–8 m-equiv. Ca/100 g., a considerably larger one in a soil containing 2 m-equiv.5. Only small differences occurred in the ratio of 89Sr to calcium between lucerne and rye-grass. This comparison was not made beyond the first 6 months of growth.6. Experiments carried out with established pastures on four soil types indicate that 89Sr is more readily absorbed from the ‘plant-base’ than after incorporation with soil. Ploughing and reseeding may reduce the ratio of 89Sr to calcium in herbage by a factor of up to 4. This effect may be greater on mature swards.7. The liming of contaminated swards reduces the ratio of 89Sr to calcium in herbage by a factor of 2 to 3 regardless of the calcium content of the soil, and liming followed by ploughing and reseeding by a factor of 3 to 7.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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