Contribution of Leaf Photosynthesis towards Seed Yield in Brassica species

The effect of defoliation after flowering, when a considerable number of pods were already formed on yield components, was examined in four Brassica species. In B. campestris and B. juncea , a decrease in seed yield by defoliation was associated with a decrease in the number of pods per plant as seed number per pod and thousand-seed weight were not significantly affected by this treatment. In B. nigra , apart from decreasing the pod number per plant, defoliation also significantly decreased the thousand-seed weight, Defoliation significantly decreased both seed number per pod and thousand-seed weight apart from decreasing the number of pods per plant in B. carinata. The study indicated that in B. campestris and B. juncea , the role of leaf photosynthesis seemed to be restricted mainly to the formation of pods. On the other hand, in B. nigra and B. carinata it appeared that leaf photosynthesis also contributed towards seed development.     

Putrescine Increases Floral Retention, Pod Set and Seed Yield in Cold Stressed Chickpea

Chickpea (Cicer arietinum L.) is sensitive to cold stress (<8 °C) at its reproductive phase that results in flower abortion, poor pod set and thus reduced yield. Early maturing genotypes are especially more sensitive. In this crop, the metabolic causes underlying cold injury that are imperative to induce cold tolerance are not known. In the present study, the endogenous levels of putrescine (diamine), spermidine (triamine) and spermine (tetramine) were examined in early maturing chickpea genotype ICCV 96029, subjected to chilling temperatures of field (12–15/4–6 °C; average maximum and minimum temperature respectively), at flowering or early podding stage. These were compared with controls growing in warmer conditions (28/12 °C) of the glasshouse. The polyamine levels increased six to nine times because of stress. Relatively, putrescine (PUT) elevation was the highest but short-lived and its decrease appeared to match with the onset of flower and pod abscission in stressed plants. Compared with controls, chilling injury, observed as electrolyte leakage (EL), increased by 60 % while cellular respiration declined by 68 % in stressed plants. Exogenous application of 10 mm PUT to stressed plants reduced the EL by 29 % and elevated the cellular respiration by 40 %. PUT application at flowering stage resulted in increase of 30, 31, 23 and 25 % in floral retention, pod set, pod retention and fertile pods respectively. At the early podding stage, PUT treatment increased the seed yield per plant, seed number per 100 pods and individual seed weight by 50, 17 and 19 % respectively. The number of single-seeded pods per plant increased from 4.4 in stressed plants to 12.2 in PUT-treated plants while the number of double-seeded pods reduced from 6.2 to 4.3. The number of infertile pods declined from 8.2 in stressed plants to 3.1 in PUT-treated plants.     

Contribution of incident solar radiation on leaves and pods to soybean seed weight and composition

The weight and composition of soybean seeds (Glycine Max L. Merrill) depend on changes in carbon and nitrogen assimilate supply during grain filling. Soybean pods and seeds are green, evidencing their capacity to capture light. However, the current physiological knowledge does not consider any effect of incident solar radiation reaching the pods on seed weight and composition. The objective of this work was to investigate the response of seed weight and composition to changes in assimilate supply from leaves, to the incident solar radiation reaching the pods and to the combination of both, changes in assimilate supply from the leaves and incident solar radiation on pods of soybean plants. Field experiments were performed during two growing seasons at Balcarce, Argentina. Treatments modified the amount of assimilates supplied by the leaves (plant shading, defoliation), the solar radiation reaching the pods (pod shading) or both (defoliation and pod shading) during seed filling. Plant shading and defoliation reduced seed weight, oil concentration and oil and protein content and increased the concentration of saturated and poli-unsaturated fatty acids while reduced oleic acid percentage. Pod shading increased the concentration of stearic acid and reduced the concentration of linolenic acid. When pods were shaded on defoliated plants, seed weight and oil and protein content decreased while fatty acid composition was similar to values obtained under defoliation treatment. Based on these results, a conceptual model that considers photoheterotrophic nature of reproductive structures of soybean is proposed. Seed weight, oil and protein content and oil fatty acid composition depended on assimilate availability for the seeds. The response of oil and protein content to assimilate supply depended on whether leaves were present or not. The effect of solar radiation incident on pods depended on the amount of assimilates available for the seeds: (i) when carbon allocated was low (defoliation treatments), pods contributed to seed carbon economy but solar radiation incident on them did not affect fatty acid composition; (ii) when carbon allocated to the seeds was high (intact plants), contribution of pods to seed carbon economy was not significant, but the amount of solar radiation incident on pods produced significant changes in fatty acid composition.     

Effects of Timing of Drought Stress on Abscission and Dry Matter Partitioning of Short-duration Pigeonpea

Shoot dry mass partitioning and cumulative abscission of leaf, flowers and pods were determined for nine short-duration pigeonpea genotypes grown with adequate soil moisture throughout growth (control), or subjected to water stress during the late vegetative and flowering (stress 1), flowering and early pod development (stress 2), or pod fill (stress 3) growth stages. The total cumulative dry mass of abscised plant parts was lower for determinate genotypes, but it increased to a greater extent under water stress than that for indeterminate genotypes, with stress 2 having the greatest and stress 3 die least effects. The dry mass contribution of pods to total abscission was ≤ 5%, and not signiflcantiy affected by water stress, while the contribution of leaves increased and mat of flowers decreased. Stress 3 had no significant effects on abscission dry mass totals or components. Reduction in shoot dry mass under water stress was most pronounced for genotypes in die early pod development stage, and the dry mass contribution of leaves generally decreased and that of pods increased under stress 1 and stress 2. With similar abscission levels, the shoot dry mass of genotype ICPL 151, was similar to, or greater than, that of hybrid ICPH 9, under stress 1 and stress 2, and the contribution of pods to shoot dry mass was lower for hybrid ICPH 9 under both stress treatments. Genotypic differences in drought resistance were likely due to differences in the leaf area maintenance during, and in the recovery of dry mass and pod production following, water stress periods.     

Reproductive Abscission and Yield of Irrigated and Drought Stressed Cowpea

Two experiments were conducted under field conditions to evaluate reproductive abscission, seed yield and yield components of three cowpea [Vigna unguiculata (L.) Walp.] genotypes. In the first experiment, level of abscission and yield of two cultivars, California Blackeye Pea No. 5 (CA-5) and Speckle Purple Hull (SPH), and one experimental line (AZ-54) were studied. In the second experiment, effect of drought stress on abscission at three nodal positions, seed yield, and yield components of CA-5 were studied. Abscission in both experiments was determined by counting scars left by dropprd reproductive structures including floral buds, open flowers, and immature pods. Abscission of CA-5 and AZ-54 in the first experiment ranged between 68 and 76 % while that of SPH ranged between 86 and 89 %. CA-5 and AZ-54 retained two to three pods per peduncle, and SPH retained only one mature pod per peduncle. Average seed yields of SPH and AZ-54, respectively, were 45 and 50 % of CA-5. Drought stress in the second experiment did not affect production of floral buds Peduncle^?1 (average of 10) but significantly increased percent reproductive abscission and decreased pod retention of CA-5. Abscission in the bottom two-third nodes increased from 82 % in well-irrigated plants to 93 % in non-irrigated plants. This increase in abscission corresponded to nearly 60 % reduction in pod retention. The number of pods per peduncle in the bottom two-third nodes decreased from 1.9 in well-irrigated plants to only. 77 in non-irrigated plants. The increase in abscission and decrease in pod retention with increasing intensity of drought was greatest in the bottom one-third nodes. Drought stress did not affect abscission and pod retention in the top one-third nodes. Stress also decreased peduncles plant^?1, seeds pod^?1, and dry matter and seed yield plant^?1 but did not affect seed weight and harvest index. The decrease in seed yield was largely due to reductions in pods plant^?1 and seeds pod^?1. The reduction in the number of pods and, therefore, seed yield due to stress was because of reductions in the number of peduncles plant^?1 and increases in reproductive abscission. It is concluded external conditions that increase abscission beyond that of normal occurrence affect seed yield adversely.     

Effects of Faba Bean Leaves in Different Positions on the Yield and Photosynthetic Compensation after Defoliation

In a field experiment in the winter seasons of 1985/86 and 1988/89 at Xichang, China, the effects of defoliation on seed yield of Vicia faba and its photosynthetic compensation were investigated by removing all leaves, some leaves from different plant positions at the beginning of flowering and the beginning of pod formation. Seed yield decreased by 37.3–52.3 % in plants with upper leaves removed at the beginning of flowering. Removal of middle leaves at the beginning of pod formation had the most significant effect, followed by the of upper and lower leaves removed, causing yield decreases of 43.4–64.3 %, 18.6–24.7 % and 8.9–12.3 %, respectively. Removal of leaves at the beginning of pod formation resulted in a greater reduction in seed yield, total dry weight, harvest index, and number of pods and seeds per plant than leaf removal at the beginning of flowering.
The photosynthetic rate and export rate of photosynthate of upper leaves at the beginning of flowering, and middle leaves at the beginning of pod formation were the greatest during both years of the experiment. Photosynthetic rate increased and reached its maximum at 4–5 days after leaf removal, then decreased, but, yet greater than the control leaves at 9–11 days after leaf removal. In the meantime, transport of photosynthetic products was accelerated. In general, removal of leaves from the upper and middle third of the plant increased the export rate of photosynthate by ca. 20 %. Photosynthetic compensation could not fully make up the loss caused by leaf removal, so grain yield was decreased by all treatments. The full defoliation decreased yield by > 70 %.     

长豇豆几个数量性状杂种优势的研究

此试验利用长豇豆（Vignaunguiculatassp.Sesquipedalis(L)Verd.）7个品种，采用Griffing第2套方案配制21个杂交组合，对长豇豆的7个数量性状进行了杂种优势分析和配合力分析。结果表明，单株结荚数、单荚重、荚长、早期产量等性状为正向优势，第一花序节位、开花前天数、开花至嫩荚成熟天数为负向优势。     

豇豆种质资源农艺性状的相关性、主成分及聚类分析

为给豇豆育种中品种资源的合理利用提供依据,对41份豇豆品种资源15项主要农艺性状进行相关性、主成分和聚类分析。结果表明,枯萎病发生程度的变异系数最大,与豇豆产量关系密切的单荚重和单株嫩荚数2个农艺性状,与株型、嫩荚长、单株花序数和单荚种子粒数都呈现显著正相关,单株嫩荚数与开花期、叶宽和单株分枝数呈现显著负相关。15个主要农艺性状可以归纳为5个主成分,第1主成分包括株型、初花节位、嫩荚长、单荚重、单荚种子粒数、单株花序数、单株嫩荚数和单株分枝数;第2主成分包括开花期、叶长和叶宽;第3主成分包括种皮颜色和嫩荚宽;第4主成分包括嫩荚颜色;第5主成分包括枯萎病发生程度。41份豇豆种质资源在遗传距离为25处分为2大类,在遗传距离为15处分为Ⅰ、Ⅱ、Ⅲ类,其中第Ⅰ类的品种优势明显,具有较好的应用前景。     

Early Generation Selection for Grain Yield in Narrow-Leaf Lupin (Lupinus angustifolius L.)

Experiments were conducted with early segregating generations of a selected narrow-leaf lupin cross to determine the effectiveness of selection for yield based on alternative criteria. F2 plants were selected on the basis of seed yield and several other yield-related characters to generate separate F3 populations. Randomly selected plants from each population were grown over the summer (off-season) in a glasshouse to generate F4 populations. Analyses of relationships between F2 plant measurements and F3 progeny mean yields revealed significant correlations only for those characters with the highest heritabilities - flowering time, 100 seed weight and harvest index. However, selection for the earliest flowering F2 plants followed by selection within this group of plants with the highest number of pod bearing branches would result in the greatest increase in F3 mean yield. The F2-derived F4 populations with the highest seed yields were those obtained by selection for total plant dry weight, number of pod bearing branches and number of pods per plant. Improvement in commercial crop yield should therefore be obtained through selection in early generations for those characters contributing to the greatest number of pods per unit area. A scheme involving selection for early flowering and high number of pod bearing branches in the F2 combined with replicated yield tests in the F4 is proposed.     

DTA-6对大豆花荚脱落纤维素酶和GmAC基因表达的调控

叶面喷施生长调节剂(PGRs)可以调控大豆花荚脱落。2012-2013年在大庆林甸县黑龙江八一农垦大学试验基地采用大田小区试验,R1期对大豆绥农28(SN28)、垦丰16 (KF16)和合丰50 (HF50)分别叶面喷施DTA-6调节剂,对调控花荚离区脱落纤维素酶(GmAC)基因相对表达量、荚脱落纤维素酶(AC)活性、花荚脱落率和产量进行了研究。结果表明：DTA-6抑制大豆花荚离区GmAC基因相对表达量,最大可达51% (±CK%);大豆荚的AC活性能够在喷药后阶段性地被降低,在不同品种上增加和降低存在差异;能够显著降低花荚脱落率(P<0.05);能够显著增加产量(P<0.05)。植物生长调节剂DTA-6是通过降低花荚离区GmAC基因相对表达量,调节AC活性,从而减少植株的花荚脱落率,以实现对产量的调控。     

Chemical Manipulation of Reproductive Efficiency of Chickpea (Cicer arietinnum L.) by Triadimefon in Relation to Changes in Ethylene

Reproductive efficiency was successfully manipulated by the application of different concentrations of triadimefon at pre‐flowering, flowering and post‐flowering stages in chickpea (Cicer arietinum L.). Triadimefon improved the parameters determining reproductive efficiency. Yield was significantly improved due to reductions in flower and pod abscission by the application of triadimefon, which also lowered the ethylene levels in leaves, flowers and pods and delayed senescence. These findings suggest a relationship between ethylene level and reproductive efficiency in chickpea. Further, they indicate that triadimefon can be used for chemical manipulation of the reproductive efficiency of chickpea under field conditions.     

Plant character correlations and path analysis of pod yield in okra (Abelmoschus esculentus)

Summary Genotypic, phenotypic and environmental correlation coefficients were calculated for fifteen characters during two growing seasons. Correlation coefficients varie between seasons. Edible pod weight, edible pod length, edible pod width, number of seeds per plant, weight of 100 seeds, length of mature pods and number of branches per plant showed significant genotypic correlation with pod yield per plant; only number of branches per plant, edible pod length and weight of 100 seeds were phenotypically correlated with pod yield. Environmental correlation coefficients were generally low but edible pod length, final plant height and edible pod weight showed significant environmental correlation with pod yield during the two seasons.The genotypic correlation coefficients of selected eight characters with pod yield were partitioned into direct and indirect causes. In the early seasons, edible pod weight had the largest positive direct effect on pod yield with its largest indirect effect through reduction in edible pod width. Edible pod width which was highly correlated with pod yield had a negative direct effect on pod yield. In the late season, edible pod weight had the largest direct effect on pod yield, with large indirect effects through reduction in number of days to flowering and number of pods per plant. Number of days to flowering had a large direct effect on pod yield with its largest indirect effect through reduction in edible pod weight. The residual factors during the two seasons were negative. The study indicated that only number of branches per plant, edible pod length and weight of 100 seeds would be useful for indirect selection for pod yield. The path analysis indicated that edible pod weight was the most reliable and effective character to select for when high yield is the objective.     

Effects of Partial Defoliation on Sucrose Accumulation, Enzyme Activity and Agronomic Parameters in Sugar cane (Saccharum spp.)

Mechanical defoliation of sugar cane plants (Saccharum spp.) will provide leaves that can be used as fodder. The effect of partial mechanical defoliation on sucrose content, enzyme activities and agronomic parameters of sugar cane is still unknown. We investigated how sucrose accumulation, activities of sucrose phosphate synthase, soluble acid invertase, sucrose synthase, neutral invertase, brix grades, purity grade, moisture content, fibre content, maturity index and reduced sugars of two commercial sugar cane plants (Mex 69‐290 and Mex 57‐473) were affected in a field experiment. The concentration of sucrose in stems of partial defoliated plants was not significantly different from that found in intact plants. Agronomic parameters and enzyme activities were not different in defoliated plants compared with intact plants except for the moisture content which was higher in defoliated plants than in intact ones. These results indicated that sugar cane plants could be partially defoliated without changing sucrose production and agronomic parameters while providing leaves that could be used as fodder.     

Temporal profiles of pod production and pod set in soybean

The distribution of flower and pod production during flowering may be an important determinant of pod and seed number in grain crops. We characterized the dynamics of small pod production and survival to maturity on indeterminate and determinate soybean [Glycine max (L.) Merrill)] cultivars growing in the field or greenhouse. Two soybean cultivars (maturity group IV, indeterminate and determinate) were grown in the field near Lexington, KY (38°N latitude) in 2001 and 2002 in 0.76 cm rows using late May and late June (2002 only) planting dates, and normal (24 plants m⁻²) and low (9 plants m⁻², 2002 only) plant populations. Cultivar Elgin 87 (indeterminate, maturity group II) was grown in a greenhouse in 3.0 L pots with one plant per pot. All unmarked pods that were ≥10 mm long were marked with acrylic paint at the base of the pod at 3-day intervals. Paint color was changed at each marking to provide a temporal profile of pod production and pod survival. The pod production (marked pods) period was longer in the indeterminate cultivar (nearly 50 days after R1) than the determinate cultivar (≤40 days after R1). Delayed planting shortened the pod-production period, but a two- to three-fold difference in pods per plant, created by changing plant population, did not affect it. The temporal distribution of small pods that survived to maturity (full sized pods with at least one normal seed) closely followed the distribution of pod production in all experiments. Some surviving pods initiated growth after the beginning of seed filling (i.e., between growth stage R5 and R6), but most of the pods were initiated in a much shorter interval (up to 84% were initiated in <40% of the period) before R5. Abortion of pods >10 mm long was relatively low (20–30%), so production of a pod ≥10 mm long seems to be a key event in the pod set process. The average length of the pod set period at individual nodes on the main stem was larger for the determinate cultivar (14 days) than for the indeterminate (9 days), so the longer total period in the indeterminate cultivar resulted from the delay in initating pod production at the upper nodes on the main stem. Temporal profiles of pod production and pod set seem to be more sensitive to changes in flower and main stem node production than to changes in photosynthesis per plant (created by varying plant population). These results provide some of the information needed to integrate time into models predicting pod and seed number.     

Shortening the generation cycle in faba bean (Vicia faba) by application of cytokinin and cold stress to assist speed breeding

The aim of this study was to reduce the length of the breeding cycle for faba bean by accelerating seed setting. We examined the mode and time of exogenous 6-benzylaminopurine (BAP) (cytokinin) application, and cold treatments and their combinations in two faba bean genotypes. Acropetal node number of pod and seed set and pollen viability were recorded during the experiments. Application of BAP improved pollen germination. The application of 10^–5 M BAP 4 days after flowering increased seed set at the lower nodes. Cold treatment (8/4°C day/night for 2 days) after the onset of flowering induced the formation of more pods and faster pod set compared to the non-cold treatment. The time to first seed was significantly reduced, and pollen viability was increased in plants exposed to cold treatment. Increased pollen viability also showed a significant positive correlation with seed setting. The combinations of 10^–5 BAP and cold treatment together had similar and independent effects. These results will accelerate plant breeding in faba bean by providing additional tools for reducing generation time.     

花生单株生产力与主要农艺性状间的相关性研究

为了解各主要农艺性状对花生单株生产力影响的主次关系,利用来源于5个国家的126份花生栽培种资源为试验材料,通过表型相关性分析和灰色关联度分析相结合的方法,探讨了12个农艺性状与单株生产力之间的密切程度。结果表明：单株总果数和单株饱果数对花生单株生产力的影响最大,其次为结果枝数和百仁重;而主茎高、侧枝长、出仁率和公斤果数对其影响较小。单株总果数、单株饱果数、结果枝数与单株生产力的表型、遗传型和环境相关系数大小基本一致,而出仁率与单株生产力之间的环境相关系数为0.185,显著小于表型(0.521)和遗传型(0.650)相关系数;且从单个性状的广义遗传率来看,单株总果数、单株饱果数和结果枝数的广义遗传率均小于50%,百仁重的广义遗传率为88.8%。综上所述,在选育高产花生新品种的过程中,首先应注重大籽品系的选育,其次考虑单株果数和结果枝数多的品系。且通过单株果数和结果枝数性状来选育高产花生新品种时,需考虑环境因素对产量的影响。     

Regulation of Correlative Senescence in Arachis hypogaea L. by Source-Sink Alteration through Physical and Hormonal Means

Amongst the plants ( Arachis hypogaea ) subjected to differential reproductive manipulations, the leaf levels of chlorophyll and sugar and the dry weight of the aerial plants increased more (except sugar level in defruited plant) in the deflorated plants than either in the defruited or control plants, and the order of senescence was: control > defruited > deflorated. Seed yield per plant increased in deflorated plants as a result of increase in the number of pods (sink size) and reduction in the sink strength (seed wt per pod). While 75 % defoliation caused a decrease in all the parameters relating to senescence (chlorophyll, protein, reduced nitrogen, sugar and dry wt), 25% defoliation caused a slight decrease of chlorophyll level of leaf and aerial plant weight. However, the level of protein and reduced nitrogen in the leaf and sugar in the stem increased by the latter (through 25% defoliation). Defoliation up to 25% reduced seed yield by only 2%. Whereas the level of chlorophyll and aerial plant dry weight were not significantly changed by either kinetin or ABA, the level of protein and reduced nitrogen in the leaf and sugar level in both leaf and stem increased by kinetin. GA₃ increased almost all the parameters studied. All the three phytohormones increased the yield, mainly by increasing the sink size rather than the sink strength. It is concluded that the aerial flowers are more lethal than the underground fruits in inducing whole plant senescence where the leaf senescence is uncoupled from fruit maturation in normal condition possibly due to sink limitation.     

菜用大豆落花落荚率与品种生育阶段的关系

本文采用单因素随机区组设计,研究菜用大豆品种生育阶段遗传差异对花荚脱落率的影响。结果表明：菜用大豆花荚脱落与各生育时期生育日数的遗传差异达极显著;花荚脱落率不仅与品种的开花阶段、结荚阶段日数呈极显著负相关,并均有显著的回归线性效应。     

Yield, yield components and plant architecture in the F3 generation of common bean (Phaseolus vulgaris L.) derived from a cross between the determinate cultivar ‘Prelude’ and an indeterminate landrace

Growth trials were conducted outdoors in the UK to determine the yield, yield components and plant architectural differences between determinate and indeterminate Phaseolus vulgaris bean plants. F3 lines derived from crosses between ‘Prelude’, a determinate cultivar and ‘V8’, an indeterminate landrace, were grown together with the parents and ‘Carioca’, an indeterminate landrace from Brazil. Data were recorded on flowering date, number of nodes on main stem at flowering, plant height at maturity, number of pods/plant, number of seeds/pod, number of seeds/plant, 100-seed weight, seed mass/plant, percentages of diseased and healthy seeds/plant. Determinate F3 lines had significantly lower (P < 0.05) seed mass/plant, fewer pods/plant, fewer seeds/pod, fewer seeds/plant, lower harvest index, shorter stems, earlier date of flowering, fewer nodes at flowering and fewer healthy seeds/plant than indeterminate F3 lines. However, determinate genotypes had significantly larger (P < 0.05) pods to accommodate their larger seeds compared with indeterminate lines. A similar situation was found when the yield and yield components of ‘V8’, ‘Prelude’ and ‘Carioca’ were evaluated; the highest seed mass/plant was given by ‘V8’ and the lowest by ‘Prelude’. Furthermore, some indeterminate genotypes with Type IV growth habit yielded significantly higher (P < 0.05) than the high-yielding parent, ‘V8’, indicating a positive influence on seed yield by crossing different genotypes.     

Natural occurrence of autopolyploidy within the allotetraploid-cultivated peanut

The cultivated peanut is classified as an allotetraploid species. During the past several years, abnormal plants with coarse stems, thick leaves and an occasional single seed per pod have been found within different cultivars and advanced breeding lines. The spontaneous natural occurrence of these plants has been very rare, and frequently they do not produce any pods or seed. However, over a 3‐year period (2001–2003), four individual plant selections with one mature seed per plant were found and saved. In 2003, another similar plant was also found that had the same plant characteristics, except for a single branch that had normal leaves with typical two‐seeded pods. A greenhouse study was conducted during the winter of 2003–2004. The four coarse stem individual plant selections from the previous years were planted along with the check cultivar ‘Georgia Green’ and the sectorial plant found in 2003. S₁ seed from both the one‐seeded pods as well as normal two‐seeded pods were planted from the sectorial plant. Relative DNA content was measured by flow cytometry on all plants. Results from the test showed that the coarse stem, thick leaf plants with poor fruit set were autooctoploids and had about twice the DNA content when compared with the normal sectorial branch and the allotetraploid peanut cultigen.