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1.
Crosses were made between two widely grown U.S. peanut (Arachis hypogaea L.) cultivars, ‘Florunner’ and Florigiant’, and two genotypes adapted to growing conditions on the plateau of tropical Africa, ‘Makulu Red’ and 486 GKP. F2 seed populations were equally divided between Georgia and Zimbabwe. Subsequently, pedigree selection was practised simultaneously at both locations in the early segregating generations. The highest yielding pureline selections were then interchanged, and combined yield evaluations were determined over three growing seasons at each location. ‘Florunner’, ‘Florigiant’, and the Georgia pureline selections tested at the Georgia location had significantly higher pod yields than ‘Makulu Red’, 486 GKP, and the Zimbabwe selections. Conversely, the mean yield of the Zimbabwe selections tested m Zimbabwe was significantly higher than that of the Georgia selections. Thus, the breeding environment under which selection is conducted among cross populations strongly influences the yield adaptability of selected peanut genotypes.  相似文献   

2.
The quantity of N2 fixed in common bean (Phaseolus vulgaris L.) is a quantitatively inherited trait that shows sufficient genetic variability for improvement through breeding, but there is little information on gain from selection for 15N-determined N2 fixation ability. The objective was to determine whether intrapopulation recombination and selection could be used to improve N2 fixation. Four agronomically acceptable lines were selected, based on their acetylene reduction-determined N2 fixation ability, from an inbred backcross (IB) line population created from a cross between the high N2-fixing donor parent ‘Puebla 152’ and a commercial, low N2-fixing recurrent parent ‘Sanilac’. These four IB lines were intercrossed, advanced to the F3, and the six resulting F3 populations with 25 F3 families per population were evaluated for N2 fixation in a low-N field using 15N-depleted (NH4)2SO4. The six F3 population means differed significantly and were superior to ‘Sanilac’ for N2 fixation ability and yield, indicating significant improvement over ‘Sanilac’. Four F3 population means were similar to ‘Puebla 152’, indicating selection advance towards high N2 fixation while retaining favorable agronomic characteristics. Fifty percent of the F3 families were superior to ‘Sanilac’ for N2 fixation and one family exceeded ‘Puebla 152’, indicating that intrapopulation recombination produced improvement of 15N-determined N2 fixation.  相似文献   

3.
Experiments were undertaken to determine the inheritance of pod length in a cross with spring rapesecd, Brassica napus, and to assess the value of pod length as a criterion of selection for high seed yield. Analyses of patterns of variation in F2; and backcross populations derived from a cross between a short-pod line TB42 and long-pod line CA553 indicated that much of the variation in pod length could be attributed to two major genes interacting in a complementary manner. Short-pods were produced when cither one or both genes were homozygous for the recessive allele. Analyses of F3 progenies of selected F2 and inbred-backcross lines derived from the same cross supported the two-gene hypothesis but also indicated that the effects of the major genes on pod length were possibly modified by genes of minor effect. Field testing of families derived from random intermating between F2, plants of the TB42 × CA553 cross showed that number of pods per plant varied independently of pod length, but seed weight per pod tended to increase with increasing pod length. As a result, families with the longest pods generally had significantly higher yields than those with short pods. It was concluded that yield improvement in B. napus could be achieved through introgression of long-pod genes into cultivars with an appropriate genetic background to ensure that selection for the long-pod character would be accompanied by an increase in seed weight per pod with little or no reduction in number of pods per plant.  相似文献   

4.
S.R. Verma  M. Yunus  S.K. Sethi 《Euphytica》1998,100(1-3):15-18
Three populations of an intervarietal durum wheat cross IWP5308/PDW208, F5, F5BIP1 (population derived after intermating in F2) and F5BIP2 (population derived after intermating in BIPF1), were evaluated under three different agronomic environments for mean performance and stability of genotypes for grain yield, yield components and protein content. Though the biparental progenies indicated a higher mean performance, they did not differ significantly from progenies of the pedigree method for almost all characters. The biparental progenies, however, produced a higher number of stable genotypes for grain yield per plant, grains per ear and protein content. The F5 population had a higher number of stable genotypes for 1000 grain weight and number of tillers per plant. The BIP progenies also had a higher number of genotypes with above average mean performance, and many were significantly higher than the checks WH896 and WH542, compared with F5 progenies. Hence, in spite of high G x E interactions, the use of cycles of biparental mating and selection of top yielding lines on the basis of yield components can enable selection of stable genotypes with high protein content. Number of tillers per plant and 1000 grain weight were the yield component characters which made maximum contribution to phenotypic stability of the genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

5.
Yields of large-seeded Andean (A) common bean (Phaseolus vulgaris L.) cultivars of Chile and Nueva Granada races are 40 to 60% lower compared to their Middle American (M) counterparts of small-seeded Mesoamerica and medium-seeded Durango races. Our objective was to use the concept of congruity backcrossing between Andean x Middle American inter-gene pool [AM 11833 = A 483 (A)///// A 686 (M) //// PVA 800A(A)/// ‘Carioca’ (M)// Carioca (M)/ G 19833 (A)] and between races within Andean gene pool [i.e., intra-gene pool Andean, AA 11834 = A483 (A)//// ‘Cardinal’(A) /// ‘Blanco Español’(A) // BlancoEspañol (A) / ‘Taylor’ (A)] to compare selection for seed yield improvement of large-seeded Andean beans. Seven hundred sixty seven F2-derived F3 (F2:3) families were produced for each population. Visual appraisal for total plant performance, combined with seed yield from non-replicated plots was used for selection of 551 families in F2:3, 182 families in F2:4, and 91 families in F2:5 in each population. Eight hundred twenty three F5:6 lines were developed from the 91 F2:5 families in each population. Visual selection, combined with seed yield in non-replicated plots was again used to select 294 lines in F5:6 in each population. Similarly, 44 highest yielding F5:7 lines were selected in AM 11833 and 39 F5:7 lines in AA 11834. Thus, single plant selections were made in the F2 and F5, and plants within each plot were harvested in bulk in F3, F4, F6, and F7. Thirty nine F5:8 lines from AA 11834 and 44 lines from AM 11833, parents, and checks were evaluated at Popayán and Quilichao, Colombia in 1998 and 1999. Selected lines in both populations, on average, out-yielded the mean of their large-seeded Andean parents. Mean yield of the lines selected from AM 11833 was 50% higher than AA 11834 lines. Twelve F5:8 lines out-yielded the highest yielding Andean parents G 19833 and A 483 in AM 11833, whereas only one line yielded significantly higher (p < 0.05) than the highest yielding parent A 483 in AA 11834. However, none of selected lines out-yielded small-seeded Middle American parents used in AM 11833 (A 686 and ‘Carioca’). The mean 100 seed-weight of AA 11834 was 36 g compared to 28 G for AM 11833 F5:8 lines. Selected lines had similar days to maturity as parents in AM 11833, and matured 3 d later in AA11834. Correlation coefficients between yield and 100 seed-weight were negative in both populations. Yield and days to maturity were positively correlated in AA 11834.  相似文献   

6.
To test for the association of the eyespot of wheat cv. ‘Cappelle-Desprez’ with the structural gene encoding the isozyme Ep-A1, F3, families from the cross ‘Cappelle-Desprez’ (resistant) X ‘Chinese Spring’ (susceptible) were selected on the basis of endopeptidase phenotype. Analysis of eyespot reaction showed that Ep-Alb homozygotes were associated with a higher level of resistance than Ep-Al a homozygotes. Thus selection of the Ep-Alb allelc should assure concurrent selection of at least a part of the eyespot resistance of ‘Cappelle-Desprez’.  相似文献   

7.
The objective of this work was to develop homozygous common bean lines carrying angular leaf spot resistance genes derived from the cultivars ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’ through marker‐assisted selection. Molecular markers SCAR OPN02890, RAPD OPE04500 and OPAO12950 linked to the resistance genes of ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’, respectively, were used in segregating backcross‐derived populations to selection. DNA fingerprinting was used to select homozygous BC2F3 and BC1F3 resistant plants genetically closer to the recurrent parent. Two homozygous BC2F2:3 and two and five BC1F2:3 families derived from ‘Ruda’ vs. ‘Mexico 54’ (RM), ‘MAR 2’ (RMA) and ‘BAT 332’ (RB) crosses were selected, respectively. After only one (RMA, RB) or two backcrosses (RM), five and eight BC1F3 lines derived from RMA and RB, respectively, and seven BC2F3 lines derived from RM, with 14.9–16.6, 16.9–18.6 and 9.3–11.1% of relative genetic distances to the recurrent parent were selected. This is the first report of lines resistant to angular leaf spot carrying genes of the cultivars ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’ developed with the aid of molecular markers.  相似文献   

8.
A. Zougari    S. Guy  C. Planchon 《Plant Breeding》1995,114(4):313-316
Decreasing the lipoxygenase content of soybean (Glycine max (L.) Merr.) seed is a prerequisite for its increased use in human foods. These investigations aim to analyse the variation of lipoxygenase contents in relation to the genotype or the nitrogen nutrition of the plant. Four genotypes from a divergent selection for N2 fixation and the recurrent parent, Weber, were grown in pots, and two Bradyrhizobium japonicum strains (G.49 and SMGS1) were used. Dinitrogen fixation was estimated in situ using the acetylene–reduction assay. The lipoxygenase activity was determined polarographically on seeds taken from plants grown under controlled conditions in the presence or absence of symbiotic N2 fixation. The large genotypic variation observed for the lipoxygenase contents was enhanced by high N2 fixation. The variation range of lipoxygenase contents, which was obtained through the combination of the genotypic variation and the N2 fixation activity, was relatively large with a ratio of 2 on a seed dry–weight basis and a ratio of 2.6 when the total proteins were considered. Decreased lipoxygenase content and increased total protein content can thus be considered in parallel in a genetic context, together with more efficient N2 fixation.  相似文献   

9.
Four seed-set groups of plants, viz. unselected ‘general’ and selected ‘high’, ‘medium’ and ‘low’ were constituted in C1 generation from randomly selected autotetraploids of two pea cultivars, T 163 and 5064-S. In C2 generation, ten plants were selected at random in each of the four groups. Two seeds each from selected autotetraploids were drawn and bulked to make 20 seeds in each of the four groups to raise C3 generation. Selection resulted in a gradual shift in seed-set, though the magnitude and nature varied with the group and generation. Improvement in the seed-set from C1 to C3 generation was associated with the increase in bivalents per cell, disjunction index and total chiasmata. Increase in total chiasmata was mostly due to an increase in proximal ones. Increase in seed-set was reflected in improvement of grain yield per plant.  相似文献   

10.
The objectives of the study were to estimate the genetic components of variance, predict the response to selection and to evaluate observed response to selection using two populations namely, PSB 7 and PSB 3, of pearl millet (Pennisetum americanum [L.] Leeks). The observed response was studied using four methods of selection based on single and multitrait criteria in three types of families, namely S1, half-sib (HS) and full-sib (FS) families. One hundred SI, HS and FS families each were developed in PSB 7 and PSB 3. Plants within a population were pollinated with bulk pollen of other population to develop HS families. Crosses were made between a pair of plants using one plant from each of the two populations to develop PS families. Data were recorded on days to flower, plant height, tiller number, spike length, spike girth, seed yield per plant and spike weight. Additive genetic variance estimates were significant for all traits. The estimates of dominance and additive × location and dominance × location interaction components were not significant, except additive × location component in PSB 7 for seed yield and spike weight. The genotypic component of variance among S1 families and S1 × location interactions were significant except S1 × location interactions in PSB 7 for days to flower, spike length and spike girth. Twenty-four strains were developed by intermating superior families identified on the basis of four selection methods in each of the six types of families. The selection methods were high seed yield (YS) per se; index selection (IS) for high tiller number and long and thick spike; truncation selection (TS) for high yield among the families having days to flower and plant height lower than the population mean: and visual selection (VS) after completion of flowering for good vigour, uniformity in plant height and good inflorescence attributes. YS and IS were found to be superior to TS and VS with respect to observed genetic gains for seed yield. That advance was higher in selection among SI families as compared with FS and HS families. In general, a good agreement was noted between observed and expected responses. Expected genetic gain from FS reciprocal (R) recurrent selection was higher than the average gain from HS-R selection.  相似文献   

11.
Two approaches were used to determine the relationship between salt tolerance during seed germination and vegetative growth in tomato. First, F4 progeny families of a cross between a breeding line, ‘UCT5’ (salt sensitive at all developmental stages), and a primitive cultivar, ‘PI 174263’ (salt tolerant during germination and vegetative growth), were evaluated in separate experiments for salt tolerance during germination and vegetative growth. There were significant differences among the F4 families in both the rate of seed germination and the plant growth (dry matter production) under salt stress. There was, however, no significant correlation between the ability of seeds to germinate rapidly and the ability of plants to grow under salt stress. In the second approach, selection was made for rapid germination under salt stress in an F2 population of the same cross and the selected progeny was evaluated for salt tolerance during both germination and vegetative growth. The results indicated that selection for salt tolerance during germination significantly improved germination performance under salt stress; a realized heritability estimate of 0.73 was obtained. Selection for salt tolerance during germination, however, did not affect plant salt tolerance during vegetative growth; there was no significant difference between the selected and unselected progeny based on either absolute or relative growth under salt stress. Obviously, in these genetic materials, salt tolerance during germination and vegetative growth are controlled by different mechanisms. Thus, to develop tomato cultivars with improved salt tolerance, selection protocols that include all critical developmental stages would be desirable.  相似文献   

12.
Summary Three populations of winter wheat were formed by crossing Avrora to Sage, TAM W-101, and Danne. Approximately 10% of the F2 plants from these crosses were selected for high and low levels of number of tillers per plant, number of kernels per spike, 1000-kernel weight, and grain yield. Forty-eight solid seeded F3 lines obtained from the selected F2 plants were then selected for high and low expressions of yield components and grain yield. Realized heritabilities were estimated. Indirect responses of yield to yield component selection and direct response to selection for grain yield were measured. Heritabilities were low for tiller number, number of kernels per spike and kernel weights but were high or intermediate for grain yield when selection occurred in the F2 generation. When selection was practiced in the F3 generation, heritabilities for tiller number and yield were low, but were intermediate to high for number of kernels per spike and kernel weight and high heritabilities were found for kernel weight. Selection for kernel weight often increased grain yield; however, direct selection for grain yields was usually as effective.Journal article no. J-4488 of the Oklahoma Agri. Exp. Stn., Stillwater, Oklahoma 74074.  相似文献   

13.
Quantitative genetic theory was used to investigate selection differentials, expected and observed direct and correlated responses to simultaneous improvement of grain yield, kernel weight, and grain protein content in F3 and F4 populations of four spring wheat (Triticum aestivum L.) crosses. Selection in the F3 generation based on the Smith-Hazel index (SH) and yield was found to be superior to the other methods studied in identifying high-yielding lines, but resulted in substantial decrease in grain protein level. Consequently, a 1.0% increase in protein from selection for protein depressed grain yield as much as 536 kg/ha below the population mean, reducing the expected yield gains per generation selection cycle by 250%. The weight-free indices (EW), particularly the index involving only yield and kernel weight (EW3) and its linear approximation (EW4), and the desired gains indices were effective in improving protein content but were less efficient in selecting top-yielding lines. Selection in the opposite direction using truncation of the lowest 10% of the population based on weight-free-index involving yield, kernel weight and protein (EW2) reduced all traits significantly compared with the mean of the unselected population indicating the effectiveness of the unweighted selection index. The observed genetic gains (Ra) from selection based on yield, the SH, EW3 and EW4 indices were slightly lower than the expected advances per cycle (R) in populations from crosses ‘Sinton’בGlenlea’ (C1), ‘Glenlea’בNB505’ (C2), and ‘A2P5’בNB320’ (C6) (Ra/R = 70 to 85%) but were higher in cross ‘NB505’בA2P5’ (C5) (Ra/R = 126 to 143%). It was concluded that weight-free and the desired gains indices can be used to improve wheat grain yield and grain protein simultaneously in F3 generation selection, as revealed by response to selection measured in the F4 generation.  相似文献   

14.
F. Veronesi 《Plant Breeding》1990,105(4):321-326
The objective of the study was to determine the effect of selection for large root dimension on root and shoot characteristics of an Italian variety of Lolium perenne L. (cv. ‘Vejo’). Two cycles of recurrent restricted phenotypic selection (RRPS) were carried out in 1983 and 1984 at Perugia (Italy). In each cycle, 20 out of 1,500 plants were selected and intercrossed under isolation. In 1985, 120 plants from‘Vejo selected’ and an equal number of plants from‘Vejo’ initial seed-lot were grown hydroponically for 92 days; at the end of the experiment, the plants were measured for their number of leaves and stems, leaf length, length of the longest root, root volume and shoot and root dry weight. Sufficient genetic variability existed among plants of cv. ‘Vejo’ to allow highly significant responses to selection for root dimension (+25 % in root length, +39 % in root volume, + 67 % in root dry weight and +31 % in root: shoot dry weight ratio). Furthermore, two cycles of RRPS for root dimension did not show negative responses of the above-ground parts of the plant.  相似文献   

15.
E. E. Mahdy 《Plant Breeding》1988,101(3):245-249
The breeding materials used in this study were the F3, F4 and F5-generations of the cross between Giza 158 × Sonora 64 (Triticum aestivum L.). The objective of this study was to compare the relative merits of Smith-Hazel, desired gain selection indices, independent culling levels and single trait selection in improving grain yield, heading date and several agronomic traits. Highly significant differences among F3 families and a satisfactory genotypic coefficient of variability were obtained for all the traits studied. The genotypic correlations were high between yield and each of spike weight, kernels/spike and spikes; plant, intermediate with 1000 kernel weight and very low with heading date, plant height and spike1 length-After two cycles of selection, the results of the gains realized indicated that the most effective method for improving yield was the Smith-Hazel index (SH7) of seven traits followed by the desired gain index of seven traits (DG7), SH5, independent culling levels, DG5 and direct selection (or grain yield/plant. Direct selection for heading date, plant height and spike length was the best method for improving these traits, but undesirable correlated responses in the other traits were obtained.  相似文献   

16.
Estimates of N2 fixation in segregating populations of bean plants based on 15N-isotope methods are technically demanding and expensive; therefore, indirect measures based on related traits including total seed N were used to select for improved N2 fixation and yield. In 1985, six populations of F2-derived F3 families resulting from six parental lines crossed to a common tester were grown in field trials on a low-N soil. In 1986, 25 selected half-sib families and two populations of full-sib F4 families were grown under similar conditions. Parents and a non-nodulating soybean line were included both years. Narrow sense (HNS) heritability estimates based on parent-offspring regressions ranged from 0.57 for total seed N to 0.39 for shoot biomass in one population, but were near zero for all measured traits in a second population. Among the criteria used to identify parental lines with superior potential for producing progenies with high total seed N, testcross population means combined with estimates of realized heritability were the most reliable. Selection of the best F3 families for total seed N resulted in F4 families with increased total seed N and higher seed yields, while seed protein percentage was unchanged. When plants are grown on low-N soils, selection for total seed N offers a useful alternative to selection for increased N2 fixation based on 15N-isotopic or total-N-difference method.  相似文献   

17.
Taro (Colocasia esculenta) is the tropical root crop species featuring the greatest flavonoids diversity. Their quantification is important for breeding programmes focusing on biofortification. This study aims at developing an HPTLC protocol to compare the flavonoids fingerprints of more than 1800 hybrids belonging to 24 full‐sib families and to select genotypes with high levels of antioxidants. Twenty different chemical markers were identified based on bands Rf and colour. Flavonoids differ among individuals both quantitatively and qualitatively. Marker ‘A’ yielded the strongest antioxidant response to DPPH, equivalent to the one with quercetin pure standard. Overall, 377 high flavonoids content (HFC) hybrids were selected from 14 different families. The mean corm weight of HFC hybrids always appeared higher than the mean corm weight of the family they belong to. This method allows unambiguous selection of HFC hybrids. It also contributes to taro genetic improvement for nutritional value and access to new markets and to strengthen corm tolerance to pests and diseases. It could be applied to other tropical root crop species.  相似文献   

18.
The effectiveness of early generation selection under low and high plant density was evaluated in faba bean (Vicia faba L.). For this, the faba bean cv. 'Polycarpe' was pollinated by eight higher yielding cultivars of different origin. The F1's and F2's together with 'Polycarpe' and the pollinator with the highest yielding ability (cv. 'Effe') were evaluated under high plant density with adjacent controls and under low plant density in a honeycomb design. It was found that the eight hybrids had a different ranking at low than at high plant density for both generations (F1and F2). Hybrid Pol.x A-58 had the best combined yield performance in the F1and F2under high and hybrid Pol.x A-37 under low plant density. Application of individual plant selection in the F2and F3generation of the two crosses (Pol.x A-58 and Pol.x A-37), under both low plant density according to UNR-O honeycomb design and high plant density using a moving average, resulted in the selection of four groups with 20 selected F3plants each. Within each group, equal numbers of seeds from each plant were mixed to establish four mixtures. These mixtures together with two controls ('Polycarpe' and 'Effe') were evaluated in a randomized complete block design (22 plants/m2) in one location for two years. It was found that the material selected continuously under low plant density had a significantly higher yield than the material selected under high plant density. In addition, the material selected from Pol.x A-37 (H1R2) under high plant density had a lower mean yield than that selected continuously under low plant density (H1H2). Their average yield over years was significantly higher than the yield of the material selected from Pol.x A-58 under both plant densities. Furthermore, the material selected from Pol.x A-58 under low plant density, had a significantly higher mean yield over years than its sibs selected under high plant density. It was concluded that honeycomb selection at low plant density can be used effectively for early generation selection in faba bean.  相似文献   

19.
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.  相似文献   

20.
以来自湖北和湖南5个地区的21个红椿优树半同胞家系为研究材料,在四川泸县进行分家系容器育苗,通过对1年生容器苗苗高和地径的观测和分析,进行苗期生长比较与优良家系选择,以期为红椿苗期优良家系选择及后续的良种选育提供参考.结果表明,不同家系苗高和地径变幅分别为14.33~55.50 cm和3.03~6.64 mm,不同家系...  相似文献   

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