Determining relationships among yield and some yield components using path coefficient analysis in chickpea (Cicer arietinum L.)

Chickpea is an important source of protein and has a major role at human nutrition and it is essential to know the relationships between yield and its components in chickpea breeding programs. In this study, five chickpea lines provided from the chickpea breeding program of Field Crops Department, Faculty of Agriculture, Ankara University were used. In the examined characteristics, positive and significant relationships were found statistically between the number of seeds pod⁻¹ and the number of pods plant⁻¹, between the number of seeds plant⁻¹ and the number of pods plant⁻¹ and the number of seeds pod⁻¹, between seed yield plant⁻¹ and the number of pods plant⁻¹, the number of seeds pod⁻¹, the number of seeds plant⁻¹; between the number of seeds pod⁻¹ and seed yield unit⁻¹ area; between the number of seeds plant⁻¹ and seed yield unit⁻¹ area. Negative and significant relationships were determined statistically between the number of pods plant⁻¹ and 100 seed weight, between the number of seeds pod⁻¹ and 100 seed weight, between the number of seeds plant⁻¹ and 100 seed weight, between seed yield unit⁻¹ area and 100 seed weight. The total determining coefficient linking seed yield plant⁻¹ and seed yield unit⁻¹ area are 0.773 (77.3%) and 0.488 (48.8%) respectively in the model which were used in our research. And also total determining coefficient related to 100 seed weight was 0.896 (89.6%) in the same model.     

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.     

Traits associated with dry edible bean (Phaseolus vulgaris L.) productivity under diverse soil moisture environments

Two experiments were conducted in the Rift Valley, Ethiopia (8°N and 39°E) to determine associations between eight plant traits and seed yield, and to obtain estimates of narrow sense heritability for the traits. Experiment I evaluated seven dry edible bean cultivars/lines at two locations to simulate different soil moisture stress, including, Debre Zeit(non-stress) and Dera (moderate-stress). Experiment II evaluated 25 cultivars/lines in three environments including, Melkassa early planted (non-stress), Melkassa late planted (high-stress), and Dera (moderate-stress). A randomized-complete-block design with three replicates was used in both experiments. Plant traits evaluated were seed yield, pods plant^-1, seeds pod^-1, 100 seed weight, root dry weight, hypocotyl diameter, plant biomass, plant height and days to flowering. Plant traits that were significantly associated with seed yield were included in a stepwise-regression model to determine which trait or combination of traits provided the best model to estimate seed yield in each environment. An analysis of variance was conducted to test main effects and interactions between plant traits and environments. Significant variation among lines occurred for seed yield and all plant traits in both experiments. Strong positive correlations were observed between plant biomass and seed yield in all environments. Seed yield and pods plant^-1 were also highly associated in four of the five environments. Stepwise regression models indicated that the combination of pods plant^-1 and plant biomass consistently contributed to seed yield prediction, while other traits did not. Because both plant biomass and pods plant^-1 had moderate to high narrow sense heritability estimates and low GE interactions, they should be useful as indirect selection criteria to improve and stabilize seed yield in a breeding program. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heterosis for yield and related characters in pea

Summary To determine the levels of heterosis in F1 hybrids, four current pea (Pisum sativum L.) cultivars from southern Australia were used as female parents and crossed with 18 introduced genotypes. The 22 parents, 72 F1 hybrids and, depending on the environment, either 54 or all 72 F2 families were grown in replicated plots in four environments. Grain yield, total dry matter, harvest index, branches per plant, pods per plant, seeds per pod, hundred seed weight, plant height, onset of flowering and flowering periods were evaluated. For both the F1 and F2 generation, heterosis was determined as the superiority over the mid-parent and also over the better parent. In addition, the superiority over the best commercial cultivar was calculated. Most hybrids were higher yielding than their mid-parent but were less stable in yield across environments. Four F1 hybrids were significantly higher yielding than the best parent, by up to 26%. There were significant correlations between F1 hybrid and mid-parent value for plant height, pods per plant and hundred seed weight but not for yield. Overall, grain yield heterosis was mainly due to more pods per plant in the hybrids. The level of heterosis for yield in a poor yielding environment was higher than that in a high yielding one. Both additive and non-additive gene effects were important in the expression of all studied traits. The average level of heterosis for grain yield and total dry matter in the F2 population was half of that in F1 hybrids. The low level of inbreeding depression from the F1 to the F2 generation suggested that epistatic gene action also contributed to the expression of grain yield. Some F2 populations maintained the high yield levels of the corresponding F1 hybrids.     

Breeding for resistance to bean golden mosaic virus in an interracial population of Phaseolus vulgaris L.

Summary Eighty-three F₂-derived F₈ recombinant inbred lines (RILs) randomly selected from a population (TY 8419) of two common bean genotypes (Pinto UI 114 x ICA Pijao), the two parents, and a control cultivar (Topcrop) were screened for their reaction to bean golden mosaic virus (BGMV) under glasshouse conditions. A randomized complete block design with two replications was used. Data were recorded for disease incidence, foliar yellowing, number of pods and seeds, and yield.Significant (P<0.05) differences among the 83 RILs were recorded for all traits. Of these RILs, 11 lines did not develop any symptom, 24 lines had a mean disease incidence of 8%, 28 lines had a disease incidence of 26.6% and developed intermediate mosaic symptoms, and 20 lines were more susceptible (>50% disease incidence and severe yellowing) than either of the parents, which had 25% to 38% disease incidence and moderate symptoms. Heritability for disease incidence was 0.54±0.01, for foliar yellowing 0.36±0.13, for pods plant^-1 0.69±0.01, for seeds plant^-1 0.54±0.09, and for yield plant^-1 0.49±0.01. Gains from selection (at 20% selection pressure) for these traits were 49.5%, 31.6%, 24%, 0%, and 20%, respectively, over the mean value of all RILs. Correlation coefficients between disease incidence and foliar yellowing and among yield and its components were positive. Disease incidence and foliar yellowing showed negative associations with yield and its components.     

Marker‐assisted parentage analysis reveals high individual selfing rates in tetraploid red clover genotypes selected for seed yield

Seed yield is a major breeding target in tetraploid red clover. We investigated if marker‐assisted parentage analysis can identify progeny plants with two high seed‐yielding parents in tetraploid red clover and if this technique is more advantageous than traditional half‐sib selection. Parentage analysis was successfully performed on the progeny from the 10% highest seed‐yielding genotypes from a second‐cycle family selection trial: 16.0% of progeny were identified with a high seed‐yielding father. However, progeny plants with two high seed‐yielding parents did not produce more seeds than traditionally selected progeny (27.3 g vs. 30.7 g/plant, respectively). The 10% highest seed‐yielding genotypes displayed on average 2% self‐fertilization. Four genotypes were self‐fertile with individual selfing rates up to 20%. Our results discourage the use of marker‐assisted parentage analysis to improve seed yield in tetraploid red clover when the material has been preselected for seed yield. Breeders should be aware that intensive selection for seed yield in tetraploid red clover may inadvertently lead to selection for increased self‐fertility, which may increase inbreeding in the long term.     

Genetics of Seed Yield and its Components in Common Bean (Phaseolus vulgaris L.) of Middle-American Origin

Genetic variance, heritability, and expected response from selection arc useful in devising alternative methods and criteria of: selection. The objectives of this study were to estimate these for seed yield and its components from 200 F₂: populations involving 80 cultivars and lines of mostly small-seeded dry bush bean (Phaseolus vulgaris L.) of habits growth I, II, and III of Middle-American origin. All cultivars and lines were crossed in eight sets of ten parents each in a Design II mating system. The F₂ populations, without parents, were evaluated in the field in a replicates-in-sets design at two locations in Colombia in 1983. Estimates of additive genetic variance were significant for yield, pods/m², seeds/pod, and seed weight. Interaction with environments was also significant. Values for nonadditive genetic variance were not significant for either yield or yield components. The estimates of narrow sense heritability, based on the F₂ population mean and unbiased by genotype x environment interaction, were 0.21 ± 0.13 for yield. 20 ± 0.13 for pods/m², 0.57 ± 0.13 for seeds/pod, and 0.74 ± 0.15 for seed weight. The expected direct response from selection of the top 20 % of F₂ populations for yield per se would result in a 4.30 % increase in yield with a correlated response of 0.21 % in seed weight. In contrast, the expected gain from direct selection for seed weight would result in a 11.76 % increase in seed weight with a, correlated gain of 0.28 % for yield. Direct selection for pods/m² would decrease yield, seeds/pod and seed weight, while direct selection for seeds/pod would reduce pods/m² and seed weight but increase seed yield by 0.37 %. Data on yield from replicated trials in the early segregating generations could be utilized for identification and selection of promising crosses and families or lines with crosses for dry bean yield improvement.     

Recurrent selection for yield in Glycine max using genetic male-sterility

Summary Recurrent selection, using genetic male sterility to facilitate intermating in Glycine max, was evaluated when selecting among individual space-planted S₀ soybean plants for three yield-related traits: 1) seed yield per se (YLD), 2) apparent harvest index (AHI), and 3) a selection index in which seed yield was regressed on maturity (REG). The original intermating population was a combination of the cultivar Century and two F₂ populations segregating for male sterility. The selection intensity through three cycles of selection was 20%. The YLD population increased in mean yield by 2.8±2.2 g plant^-1 cycle^-1 buf shifted significantly toward late maturity by 3.9±0.6 days cycle^-1. The AHI population decreased in yield by 4.4±2.6 g cycle^-1 while maturity shifted slightly earlier; there was very little change in AHI. The REG population increased in yield by 5.7±2.4 g plant^-1 cycle^-1 while shifting toward later maturity by only 0.8±0.5 day cycle^-1. We concluded that selection among S₀ plants in these populations, using the selection index of yield regressed on maturity, was affective in increasing single plant yields without causing a significant shift in maturity. Selecting for yield per se caused an unacceptable shift toward late maturity and selection for AHI was ineffective for increasing yield or AHI.     

Heritability of, and genetic correlations among, forage and seed yield traits in Ladino white clover

Sixteen white clover genotypes and their half-sib progenies were grown in pure stand. Each clover progeny was also grown in a mixed stand that also included three grass varieties of different species. Dry matter (DM) yield was measured over 2 years and seed yield at the second year. Competitive ability of clover families was defined as the ratio between mixed stand and pure stand for clover DM yield. Narrow-sense heritability from parent-offspring regression of pure stand data was high to moderate (h²0.50) for DM yield, seed yield and most of their components. Persistence as predicted by stolon density showed negative genetic correlations with seed yield (r_g= -0.70) and DM yield (r₂= -0.60), whereas seed yield and DM yield tended towards a negative correlation (r₂=0.45). Sizes of different vegetative or reproductive organs were generally correlated positively. Evidence was provided that the set of parent genotypes represents well the genetic variation available within the Ladino gene pool. The results highlighted the difficulty of combining relatively short-term DM yield, persistence and seed yield into a unique plant type. Differences in competitive ability emerged only in the second year, better ability being related mainly to petiole length among the traits assessed in pure stand.     

The relative contributions of yield components to lint yield of upland cotton,Gossypium hirsutum L.

Summary Stepwise regression analyses provided an estimate of the net effect of yield components on lint yield of Upland cotton. Data from strain tests in the Pee Dee, South Carolina, cotton breeding program for crop years 1968 and 1969 were used in these analyses. Lint yield/m² was the dependent variable. Independent variables were: bolls/m², lint/seed, and seeds/boll.Correlation analyses indicated the relationships among yield components. Partial correlation coefficients were utilized to show the order of variable addition in the regression equations. We found that bolls/m² assumes the major role in determining yield. The lint/seed component assmes the secondary role in the development of lint yield. Seeds/boll made a relatively larger total contribution only after lint/seed had made its contribution.These data indicate that selection pressure should be placed on prolificacy (bolls/m²) and seeds/boll, concommitantly with selection to maintain or increase lint/seed. Although the lint/seed component makes a relatively smaller total contribution to lint yield, it is necessary to maintain or increase this component to secure the increased contributions of seeds/boll.Cooperative investigations of the Plant Science Research Division, Agricultural Research Service, US Department of Agriculture and the Tennessee and South Carolina Agricultural Experiment Stations. South Carolina Technical Contribution No 954.     

Variation for dry matter yield,seed yield and other agronomic traits in Ladino white clover landraces and natural populations

Summary A set of Ladino white clover ecotypes including the last available landraces and some natural populations collected from old permanent meadows, together with some white clover varieties of various origins, were evaluated as monocultures for dry matter (DM) and seed yield assessed in separate field experiments. Other agronomic traits were also recorded. The best performing variety, Espanso, was significantly outyielded by some ecotypes for DM and seed production. Compared to landraces, natural populations yielded on average far less seed but as much DM and tended towards higher persistence indicating that domestication of the native Ladino at the farm level only improved seed yield of the crop. Natural populations showed, besides lower values of most seed yield components, a distinct canopy architecture characterized by smaller leaves, longer internodes and denser stolons. Seed weight proved the best character discriminating between the two ecotype groups. Significant variation for most traits was found both among landraces, in which it was mostly relatable to differences among provenances, and among natural populations. The relations between the main multivariate patterns of phenotypic variation and a set of environment collecting variables suggested that evolutive adaptation to different agronomic practices was a major determinant of the overall variation found in landraces. Evidence is provided that a relevant part of the variation observed among ecotypes for some important traits could be genetic.Abbreviations DM dry matter - DMY dry matter yield - NRH number of ripe heads - NFH number of florets per head - PL petiole length - LS leaf size - IL internode length - NS number of stolons - PRO protein content - SY seed yield - TSW thousand seed weight - NSF number of seeds per floret - PCA principal components analysis - PC principal component     

Analysis of quantitative variability for seed yield and related characters in Lotus corniculatus L. cv. Leo

Summary Quantitative variability for seed yield and six other characters was analysed in Lotus corniculatus L. cv. Leo. The material consisted of 144 polycross progenies and 100 parents.Wide variability existed for all characters. The characters with the greatest variability were seed yield, forage grading and plant height. The polycross progeny test was employed to study the general combining ability of the parents. Highly significant differences existed for all seven characters under study.Parent-offspring genotypic and phenotypic correlations were high and significant for all characters except genotypic correlations for seed yield and seeds per pod. High h² values (broad sense) were obtained for seed size and days to flowering. Traits with moderate to high h² were seed yield (71% in parents, 64% in progenies), plant height, forage grading, and seeds per pod. The character pods per inflorescence had the lowest h².Positive estimates of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabiGaaiaacaqabeaadaqaaqaaaOqaaiqabo8agaqcaK% aaavaabeqaceaaaeaacaqGYaaabaGaaeiraaaaaaa!3A89!\[{\text{\hat \sigma }}\begin{array}{*{20}c} {\text{2}} \\ {\text{D}} \\ \end{array} \] were obtained only for seed size. The ratio of dominance variance to additive variance indicated partial dominance for this character. Except for seed yield, in all other cases these estimates had very high sampling errors. In all cases except pods per inflorescence and seeds per pod high positive estimates of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabiGaaiaacaqabeaadaqaaqaaaOqaaiqbeo8aZzaaja% qbaeqabiqaaaqcaauaaiaaikdaaKaaGeaacaqGbbaaaaaa!3B30!\[\hat \sigma \begin{array}{*{20}c} 2 \\ {\text{A}} \\ \end{array} \] were obtained.The data indicated that it may be possible to simultaneously improve seed yield and maintain forage yield. Seed yield had positive and significant associations with seed size, seeds per pod and pods per inflorescence. The associations of days to flowering with forage grading (negative) and with pods per inflorescence (positive) were also significant.     

高产高油花生品种的光合与物质生产特征

以冀花2号、冀花4号和鲁花12号为材料,连续测定干物质、荚果产量、含油量及叶片光合指标,定量分析高产高油花生品种冀花4号物质生产指标的动态特征和叶片光合性能,为解析花生高产高油形成机制和优质高效栽培提供依据。结果表明,荚果产量和籽仁含油量均以冀花4号最高。干物质平均积累速率和最大积累速率均以冀花4号冀花2号鲁花12号,且冀花4号干物质积累潜力适中;籽仁油分最大积累速率和平均积累速率均以冀花4号鲁花12号冀花2号,籽仁油分积累活跃期以冀花4号最短。冀花4号全生育期的光合势显著高于冀花2号和鲁花12号,分别高20%以上,产量形成期的光合势占全生育期的80%,冀花4号结荚期光合速率比冀花2号和鲁花12号均高24%以上;光饱和点和CO_2饱和点均为冀花4号最高。荚果产量与干物质平均积累速率、叶片光合速率和总光合势呈极显著正相关;籽仁含油量与单株干物质积累速率、籽仁油分平均积累速率、光饱和点、CO_2饱和点、经济系数、出仁率等显著或极显著相关;荚果产量与含油量极显著正相关。冀花4号具有较高的经济系数、总光合势及结荚期后分配比例、光合速率、光饱和点和CO_2饱和点,以及相对较高的干物质和油分积累平均速率,是其较冀花2号和鲁花12号高产高油的重要原因。     

Investigation of the fenugreek (Trigonella foenum-graecum L.) genotypes for fresh weight, seed productivity, symbiotic activity, callus formation and aceumulation of steroids

Summary As a result of the analysis of 31 fenugreek (Trigonella foenum-graecum L.) genotypes we demonstrated that subsp. indica surpass significantly subsp. foenum-graecum in fresh weight, seed yield, nodulation ability, resistance to coot rot and the duration of the interstage and growing periods. There was no difference between the subspecies for leafiness and biochemical composition of seeds (concentrations of diosgenin and steroid glucosides, nitrogen, fat, inhibitors of tripsin and hemotripsin). The most promising genotypes (as compared with the standard cv. Nakhichevanskaya Shambala) yield 1650–1938 g/m² of fresh weight, 98.2–116.1 g/m² of seeds and accumulate 1.45–1.64% of diosgenin in seeds. High positive correlations (r=+0.53 ... +0.84; P_o<0.01) were found between fresh weight, seed yield, plant leafiness and height. Inoculation of the cv. Nakhichevanskaya Shambala with Rhizobium meliloti strains 851 and 852 increased its fresh weight by 94.5% and 93.6% and seed yield by 83.1% and 60.5%, respectively. Significant correlations of the nodule number with the fresh weight and seed yield (r=+0.70 and +0.77; P_o<0.01) allow us to assume that selection for increased symbiotic activity may be useful for improving the fenugreek productivity. The intersubspecies hybrids (four genotypes) surpass the subsp. indica (six genotypes) for the sizes of calli formed in presence of 2.4-D and kinetin. The sizes of calli formed by ten analysed genotypes in presence of BAP and kinetin (or 2.4-D) were negatively correlated with the nodule number (or fresh weight).     

作物种子的营养成分与其萌发特性关系的探讨

选择7种作物种子,测定百粒重、发芽率以及发芽期间的丙二醛浓度和酶活性指标的变化情况,结果表明,种子粗脂肪与淀粉含量呈负相关,可溶性糖含量与粗脂肪含量和淀粉含量无相关关系。样本间百粒重和4d发芽率区别明显,且二者之间没有相关性;二者主要与粗脂肪含量呈正相关。发芽期间,淀粉类种子MDA含量较低且为逐步上升趋势,脂肪类种子MDA含量较高且为先升后降趋势,并且随粗脂肪含量的增加而升高,随可溶性糖和淀粉含量的增加而降低。淀粉类种子POD活性呈下降趋势,脂肪类种子POD活性变化较复杂,主要随着粗脂肪含量的增加而上升。CAT活性呈逐步上升趋势,SOD活性呈逐步下降趋势,这2个指标的变化趋势在淀粉类种子和脂肪类种子之间没有区别,主要随可溶性糖含量的增加而下降。总体来看,相对于脂肪类种子,淀粉类种子在萌发方面具有一定的优势,生产中可以适当降低播种量。种皮较厚的种子出苗率较高但发芽速度慢,生产中最好采取一定的催芽引发措施,以促进其出苗。     

Surveying the relations among traits affecting seed yield in sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.)

To determine the most important traits influencing seed yield of sesame, 18 lines were evaluated in a randomized block design with three replicates in two years during the 2013 and 2014 growing seasons. Following a combined analysis of variance, multivariate statistical analyses such as simple correlation coefficients, factor analysis, stepwise analysis, path analysis, and cluster analysis were administered on combined means. The correlation coefficient analysis showed a significant negative correlation between seed yield and number of capsules per plant and number of seeds per capsule. Correlation between germination period and seed yield was positive and significant at 5% probability level. Factor analysis divided the 14 measured variables into five factors. In the stepwise regression analysis for seed yield as the independent variable, four traits including number of capsules per plant, first capsule height, number of seeds per capsule, and stem length to first capsule were entered into the regression model in four steps with r² =0.72. The regression coefficient of number of capsules per plant, number of seeds per capsule, and stem length to first capsule were negative and the regression coefficient of the first capsule height was positive and significant at the 5% probability level. The path coefficient analysis based on seed yield as a dependent variable implicated that the number of seeds per capsule had the highest negative direct effect on seed yield. The highest negative indirect effect on seed yield was related to the number of capsules per plant through the number of seeds per capsule. Cluster analysis using Ward’s method divided 18 investigated lines into five clusters.     

Combining ability of seed vigor and seed yield in soybean

Studies have shown no consensus in relationships between seed yield and vigor in soybean [Glycine max (L.) Merrill]. The lack of information regarding the inheritance of seed vigor prompted this study to determine the types of gene action and combining ability estimates for seed vigor and its related traits. Five high and six low seed vigor soybean genotypes were crossed in a diallel, and selfed to produce 55 F₂ progenies, which were examined, along with the parents, for seed vigor, yield, and seed weight. Significant genotype and environment effects were found for seed vigor and yield. General combining ability (GCA) effects for seed vigor and seed yield were significant (p≤ 0.01) and larger than specific combining ability (SCA) effects. Significant GCA and SCA effects were found for seed weight, indicating that both additive and non additive genetic effects were involved in conditioning seed weight. The ratios of mean square, 2GCA / (2GCA+SCA), were 0.96 for seed vigor and 0.93 for seed yield. These ratios indicated that additive gene effects were more important than non additive gene effects for seed vigor and seed yield in these crosses. Mean seed vigor(83.8%), as determined by accelerated aging germination, and mean seed yield (2,155 kg ha^-1)in high vigor × high vigor crosses were higher than the high vigor × low vigor and low vigor × low vigor crosses. Mean percent accelerated aging germination rates in F₂ populations from diallel crosses were significantly related to mid-parent seed vigor(r² = 0.52^**) and midparent seed size (r² = 0.31^**). These results indicated that levels of seed vigor can be improved through breeding, while maintaining high yields because of the predominance of GCA effects in both seed vigor and seed yield. This revised version was published online in July 2006 with corrections to the Cover Date.     

两种类型蓖麻杂交种杂种优势的分析

为进一步了解蓖麻表型性状杂种优势表现特点及与亲本相应性状的关系.选用两种基因类型有明显差异的中高秆和矮杆蓖麻杂交组合的亲本CS-R6(♀)、CS-R181(♂)和CS-R63(♀)、CS-R268(♂)和它们的杂交种CS-R6.181F_1、CS-R6.181F_2、CS-R63.268F_1为研究材料.通过田间试验,测定了地上部干物质积累及在营养体和生殖体中分配速率和成熟期13个表型性状的杂种优势表现.结果表明:两种类型杂交组合的生育特点及杂种优势表现上有明显差别,CS-R6.181F_1属于生殖型为主、体质型为辅的杂种优势类型;而CS-R63.268F_1属于生殖型的杂种优势类型;中高秆杂交种CS-R6.181F_1收获期13个地上部主要性状杂种优势均表现为超高亲优势;而矮秆杂交种CS-R63.268F_1只是在籽粒产量、皮壳率和粗脂肪含量等7个性状表现为超高亲优势,百粒重等3个性状表现为超中亲优势,而营养体3个性状均表现超低亲优势,CS-R63.268F_1综合了母、父本突出的优良特性,生育期趋向父本,是适合密植和机械化栽培的杂交种;蓖麻杂种优势从杂种F_2开始出现衰退,不再适合在生产中应用.     

Seed yield related to crop development and to yield components in nine cultivars of perennial ryegrass (Lolium perenne L.)

Summary We had previously found differences for seed yield among nine perennial ryegrass cultivars which were not associated with variation for seed weight. To detect the physiological basis of these genetic differences for seed yield, growth analyses were carried out. We related crop development and components of seed yield to seed yield during three years on clay and sandy soil. No significant differences occurred among cultivars for accumulation and partitioning of dry matter or the pattern of tiller production. Seed yield of the cultivars was not associated with ear number or total dry matter yield of the seed crop. Seed yield was more correlated with the number of seeds per unit area than with seed weight. The number of seeds as calculated after harvest from seed yield and seed weight was much lower than the number of seeds as estimated prior to harvest from seed yield components. The number of spikelets differed significantly among the cultivars, but the ranking was different from that for seed yield. The physiological basis of the genetic differences for seed yield is not clear. Implications for breeding perennial ryegrass are discussed.     

Effect of the gene for double pod in chickpea on yield, yield components and stability of yield

Five pairs of near isogenic lines (NILs) for the gene for single vs. double pod were used to study the effect of this character on yield and its components (seeds per plant, yield per plant and seed weight). The NILs were sown in 2 years at five locations in ihe first year and four locations in the second. Combined analysis of variance was applied to t he data and no significant differences between isolines were found, but there were significant genotype– location interaction effects for yield and seeds per plant. For both characters the double–podded lines were more stable than the single–podded lines. Although there were significant differences between the five genotypes lor yield per planl and seed weight, the differentes between single– and double–podded lines were almost nil. The results indicate that the double–pod gene has a positive effect on the stability of yield and is not linked to any other gene responsible Tor seed size in chickpea