共查询到20条相似文献，搜索用时 78 毫秒
1.
Summary Progress was evaluated after four cycles of recurrent selection among S0 plants of Glycine max (L.) Merr. in which selection was either for maturity (MAT) or seed protein (PRO). The two populations, MAT and PRO, were developed from an initial population that was a combination of a line with 48.4% seed protein and two F2 populations segregating for male sterility. Intermating was facilitated by genetic male-sterility and the selection intensity was 20% in each cycle of the two populations. Selection for early maturity advanced the average maturity a significant 2.7±0.34 days cycle–1 and reduced seed yield a non-significant 9.1±2.95 g plant–1 cycle–1. Selection increased mean seed protein a significant 0.8±0.15 percentage points cycle–1 and decreased percent seed oil a non-significant 0.5±0.17 percentage points cycle–1. Correlation coefficients between seed protein and seed yield varied from 0.18 to –0.21 in the four cycles indicating plants with favorable combinations of seed yield and seed protein could be identified. Selection in these two populations would be effective for early maturity and for increased seed protein. 相似文献
2.
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. 相似文献
3.
Summary The objectives of this study were to evaluate the efficacy of S1-recurrent selection for increasing groat (caryopsis)-protein yield in oat (Avena sativa L.) and to compare the effects of three selection strategies on correlated responses in groat yield and groat-protein concentration. Three S1-recurrent selection programs were conducted for five cycles. Selection criteria in each program (line of descent) emphasized different components of protein yield; high grain yield in HG, both high grain yield and high groat-protein concentration in HP, and protein yield per se in HGP. Thirty to sixty random S0-derived lines from each cycle and ten check lines were evaluated in one year at two locations to estimate the response to selection. Groat-protein yield increased 4.4% cycle-1 in HG, 3.4% cycle-1 in HP, and 2.2% cycle-1 in HGP. Gains in groat yield were 7% cycle-1 in HG, 1% cycle-1 in HP, and 3% cycle-1 in HGP. Mean groat-protein yield and groat yield in the cycle 5 (C5) populations of all three lines of descent were equal to or slightly higher than those of high yielding cultivars. The HG line of descent showed a significant decrease from 193 to 175 g kg-1 groat protein, while the HP line of descent showed a significant increase from 202 to 218 g kg-1. The HGP line of descent showed a small but significant decline in groat protein from 200 to 192 g kg-1. In comparison, the high-protein commercial cultivars contained about 210 g kg-1 groat protein. The C5 population of the HP line of descent had a unique combination of high groat yield and high groat-protein concentration. Genotypic variances for groat-protein yield, groat yield, and groat-protein concentration were not always significant in the various cycles of the three lines of descent, but in no instance was there a consistent change from C0 to C5. S1-recurrent selection was effective for increasing groat-protein yield of oat, and with the proper germplasm and selection strategy both groat yield and groat-protein concentration can be improved simultaneously.Abbreviations C -
cycle
- GPC -
groat-protein concentration (a groat is the part of an oat grain that is the actual seed or caryopsis, rather than the hull)
- GPY -
groat-protein yield
- GTY -
groat yield
- HG -
selection for protein yield through high grain yield
- HGP -
selection for protein yield per se
- HP -
selection for protein yield through high grain yield and high protein concentration
Journal Paper No. J-15287 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011, USA. Project No. 2447. 相似文献
4.
T. N. Girish T. M. Gireesha M. G. Vaishali B. G. Hanamareddy Shailaja Hittalmani 《Euphytica》2006,152(2):149-161
Genetic variability, correlation, path coefficient analysis and test of normality was conducted in an F8 recombinant inbred aerobic rice population developed by single seed descent method to evaluate its potential as a mapping population. Estimates of genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability in the broad sense (H) and expected genetic advance at 5% selection index (GA) for grain yield and other attributing characters were computed. In all the cases, PCV was higher than GCV indicating the influence of environment on the characters. High heritability coupled with high GA was observed for several plant traits; number of tillers, plant height, total number of spikelets panicle−1, biomass plant−1, straw weight, harvest index and grain yield plant−1 and hence offered good scope for selection. Grain yield plant−1 was found to be positively correlated with plant height, number of tillers, panicle length, panicle exsertion, number of panicles plant−1, single panicle weight, test weight, number of fertile spikelets panicle−1, straw weight, biomass plant−1, harvest index and grain breadth both at genotypic and phenotypic levels. Harvest index exerted maximum positive direct effect, followed by biomass plant−1 and straw weight on grain yield plant−1 at phenotypic level. Shapiro-Wilks “W test of normality” indicated that the population was skewed towards female parent IR50 for some traits and for some others towards Moroberekan, the male parent. Most of the characters that showed skewness were platykurtic with a kurtosis value of less than 3. 相似文献
5.
Summary Genetic relationships of condensed tannins (CT) with other forage quality parameters have not been adequately studied in birdsfoot trefoil (Lotus corniculatus L.). The objectives were to bidirectionally select for CT concentration in birdsfoot trefoil to determine selection response and to create populations for examination of genetic relationships of CT with forage quality parameters, principally lignin. High-and low-tannin parental clones were selected from NC-83 birdsfoot trefoil germplasm and intercrossed to produce Syn1 populations. Herbage samples, harvested for two years at two locations, were analyzed from high-tannin, low-tannin, and parental populations for CT concentration, herbage yield, and forage quality parameters. The mean condensed tannin concentrations in the high-and low-tannin populations were 69.3±0.8 and 21.1±0.8 g catechin equivalent (CE) kg-1 dry matter (DM) compared with 36.4±0.8 g CE kg-1 DM in the parental population. The selection response exhibited a quadratic relationship, with selection for increased CT concentration more effective than for reduced CT concentration. Compared with the parental population, acid detergent lignin (ADL) was higher, and crude protein (CP) and in vitro digestible dry matter (IVDDM) concentrations were lower for the high-tannin population and the converse was true for the low-tannin population. Lignin concentration was positively correlated with CT concentration (rg=0.66 P0.01).Abbreviations ADF
acid detergent fiber
- ADL
acid detergent lignin
- CP
crude protein
- CT
condensed tannins
- IVDDM
in vitro digestible dry matter
- NDF
neutral detergent fiber
- NIRS
near infrared reflectance spectroscopy 相似文献
6.
Summary Soybean is an important oilseed crop in India and varieties with high yield potential are being developed since 1969. This study was conducted to assess the impact of breeding on yield and plant characteristics during the last 25 years. A 3-year field experiment was conducted to evaluate forty three soybean varieties belonging to two different selection cycles and representing most of the varieties developed in the domestic breeding programme of India from 1969 to 1993. Varieties resulting from selection cycle 1 showed 4 times higher seed yield and harvest index as compared to the farm traditional variety Kalitur. This yield increase was due to an increase in biomass, pods plant–1, mean seed weight and longer seed filling duration, but a reduced plant height and improved lodging tolerance, less seeds pod–1 and early flowering and maturity dates. The varieties of selection cycle 2 showed 19% higher seed yields and 16% increase in harvest index over selection cycle 1 accompanied by longer seed filling duration, more seeds pod–1 and reduced plant height. The annual genetic gain in seed yield of soybean varieties released in India from 1969 to 1993 was approximately 22 kg ha–1. 相似文献
7.
The F
1 and F
2 generations of a twenty parent fractional diallel cross of opium poppy (P. somniferum L.) were analyzed for combining ability for ten quantitative and five quality (alkaloids) traits. The results indicated significant
differences among the parents for combining ability for all the traits. The GCA and SCA components of variances were significant
for all the characters. However, the SCA component of variance (δ
2s) was predominant indicating the preponderance of non-additive gene effect for all the traits except for leaves/plant and
papaverine in F1 hybrids. The average degree of dominance (δ
2s/δ
2g) was more than unity indicating over dominance and also confirming non-additive mode of gene action. Among the parents IS-16,
IS-13 and NBRI-1 for early flowering, BR226 and BR241 for branches/plant, capsule weight/plant, seed yield/plant and husk
yield/plant, BR227 for leaves/plant, UO1285 for capsule size and opium yield/plant, NBRI-5 for husk yield/plant, morphine,
codeine, and thebaine and ‘Papline’ for plant height and papaverine content were found good general combiners. Parent ND1001
was good combiner for codeine and narcotine content. Inclusion of good general combiners in a multiple crossing program or
an intermating population involving all the possible crosses among them subjected to bi-parental mating may be expected to
offer maximum promise in breeding for higher opium, seed yield and alkaloid contents. 相似文献
8.
Four cycles of recurrent selection for FHB resistance were conducted in an intermating wheat breeding population using the
dominant male-sterile gene ms
2 during 1987–1991.Five cycles of phenotypic mass selection for male-sterile plants were evaluated using the soil-surface inoculation
method in Experiment I. Experiment II evaluated changes in FHB scores during five cycles of progeny selection for fertile
plants using the single-floret inoculation method. In Experiment I, the average level of FHB response increased to MR level
in C4, compared to MS level in C0. The numbers of infected spikelets and diseased kernels decreased 0.32 and 2.68 per cycle, respectively. In Experiment II,
the average level of FHB response increased to R level in C4F1. The numbers of infected spikelets and diseased kernels decreased 0.93 and 4.58 per cycle, respectively. In both experiments,
the largest selection gains were realized in the first cycle. The frequencies of R and MR individuals were increased significantly.
The frequencies of individuals with FHB response equal and/or superior to Sumai 3 were increased to 5–8% in C4 and 25% in C4F1after the fourth cycle. Agronomic traits tended to be slightly improved in selected populations. Compared to 2% in C0, about 34% of lines superior in both FHB resistance and agronomic traits in C4F1 were selected to enter the conventional breeding program for further evaluation. Sixty three semidwarf lines superior in
both FHB resistance and yield potential were selected from the F5 generations derived from C1F1 to C4F1. From them, two resistant cultivars with high-yielding potential were developed and commercialized in the Lower Yangtze Valley.
Recurrent selection appears to be highly effective and feasible in shifting the average FHB response of the intermating population
in the desirable direction, thereby enhancing the frequency of resistant individuals.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Summary Sixty tetraploid wheat (Triticum turgidum L.) landrace agrotypes collected from the central highlands of Ethiopia and one commercial check cultivar (Boohai) were evaluated at Akaki experimental station for grain yield and 11 other component traits. The objectives were to estimate phenotypic (PCV) and genetic (GCV) coefficients of variation, broad-sense heritability (H) and genetic advance (GA), and to determine the interrelationships among the various traits. Genotypic differences among the agrotypes were highly significant for all the traits considered. Compared to Boohai, the landrace agrotypes were later in days-to-heading (DTH) and maturity (DTM), and had shorter grain filling period (GFP), lower fertility (KS) and lower 1000-kernel weight (TKW). By contrast, they were superior to Boohai in tiller number (TN), biological yield (BY) and grain yield plant-1 (GYP). Intermediate to high order estimate combinations of GCV, H and GA (as % of the mean) were observed for TN, GYP, number of kernels spike-1 (NKS), harvest index (HI) and TKW. GYP showed a moderate heritability which was higher than GFP, BY and Plant height (PHt). DTH and DTM were strongly correlated, but both were negatively associated with the rest of the traits except PHt. The negative correlation of DTM with GYP was largely indirect via other characters. PHt had either a weak or negative association with the other traits. TN and TKW were positively correlated with GYP, and had high and intermediate direct effects, respectively. These two traits, however, were negatively correlated and showed a substantial counter-balance effect via one another. It appears that, for the short-term, improvement of the Ethiopian wheat landraces may be possible through indirect selection for TN and TKW or direct selection for grain yield per se. In the long-run, crossing programmes between indigenous and introduced germplasm may be necessary. 相似文献
10.
Six pearl millet (Pennisetum glaucum [L.] R. Br.) composites were subjected to three or more cycles of selection in multilocational yield trials and downy mildew disease nurseries in India. The base and selected populations were tested (a) over four years at three locations in India (11° to 29°N), (b) under terminal-drought and optimal moisture conditions for two years, and (c) under induced downy mildew infections to determine the impacts of selection on grain yield, agronomic traits, and resistance to downy mildew (Sclerospora graminicola Sacc. Schroet.). Mean grain yield increases for four composites undergoing three to six cycles of selection ranged between 23 to 94 kg ha-1 cycle-1 (0.9 to 4.9 % cycle-1) which, averaged over composites, amounted to 3.3 % cycle-1. Yield gains were generally expressed at all test locations and under both terminal-drought and optimal moisture environments. The gains in grain yield were associated with increases of both biomass and harvest index without extending the growth duration except in the earliest composite. Susceptibility to downy mildew remained below 10 % in all selected populations. Thus, the effectiveness of recurrent selection for increasing yield and yield stability of pearl millet is clearly demonstrated. 相似文献
11.
Recurrent selection programs can use several crossing arrangements to synthesize basic populations for breeding purposes.
This study evaluated heritability and correlations among traits in forty-five populations of F2[4] and F2:3[4] generations obtained throughout four-way crosses [4] between two dialells among ten semi-late and ten late maturity soybean
(Glycine max L. Merrill) genotypes. The generation advance was made by the TSHD (Thinned Single Hill Descent) method and all individual
plants were evaluated for the following traits: number of days to flowering (NDF) and maturity (NDM), plant height at flowering
(PHF) and maturity (PHM), agronomic value (AV) and seed yield (YLD). Four-way crosses associated with TSHD method provided
high genetic variability in the populations with little or no reduction from F2[4] to F2:3[4]. The ‘narrow sense’ heritability estimated using correlations between F2[4] and F2:3[4] plants was lower than but closely related to broad-sense estimates. The populations 21(IAC-4 × IAC-9) × (GO79-1039 × Paranagoiana)
and 23 (IAC-4 × Santa Rosa) × (GO79-1039 × Tropical) were the most productive with high variability in F2[4] and/or F2:3[4] generations. Genotypic correlations measured were generally high, positive and consistent for the two generations except
for those related to AV and YLD. These results indicate that the use of four-way crosses can be an efficient method to increase
the genetic base of populations for recurrent selection or cultivar development. Significant AV × YLD correlations indicated
visual selection can be used as additional selection criteria for improving populations.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
This paper aims at improving the legume landrace Fava Santorinis (Lathyrus sp.) through the study of the existing variability, and an intra-landrace pedigree, combined with analytical selection, scheme.
The experiments were conducted at the farm of Aristotle University of Thessaloniki during five growing seasons (2005–2009),
and the selection was applied on a spaced plant conditions. In the first stage, single-plant frequency distributions of the
source landrace for grain yield and pod number plant−1 was studied, and a percentage of 60.80% of non productive plants was found. In the second stage, improvement of grain yield
relied on direct pedigree selection, accomplished by analytical selection for the number of pods plant−1, plant leaf color and vigor. This procedure was followed along the first generation progenies, and, later on, along two successive
generations on the offsprings of two populations, one with purple and the other with white flower color. In the third stage,
the evaluation of the fourth-generation progenies of each population for grain yield, showed superiority ranging from 42.48
to 107.89% compared to the source landrace. Furthermore, the breeding procedure succeeded in: (i) decreasing the coefficient
of variability of grain yield and pods plant−1, thus increasing the stability of performance, (ii) reducing by 56.41 and 39.67% the non productive plants for white and
purple flower populations, respectively, and (iii) maintaining the mean and the variability for pod traits as in the original
landrace. Realized heritability for grain yield was positive during all selection cycle. 相似文献
13.
Effect of plant density on selection for seed yield in two population types of Phaseolus vulgaris L.
Summary Pedigree selection for seed yield, using early generation yield tests, was practiced from the F2 to F7 in two populations of common bean (Phaseolus vulgaris L.) in three plant densities: 66, 133, and 266 thousand plants ha-1 at CIAT-Palmira, Colombia. The six highest yielding lines selected from each plant-density, along with 13 parents, were evaluated in a 7×7 lattice design with three replications at the three densities utilized for selection, and at 399,000 plants ha-1 in 1988 and 1989.Based on the mean performance of selected lines and the mean of the parents, selection for seed yield was effective in all densities in both populations. However, none of the lines selected from the population within the race Mesoamerica (TC 4673) significantly outyielded their best parent under any plant density. The highest yielding lines selected from the interracial population (TR 4635) outyielded their best parent irrespective of the plant-density used for selection. The highest yielding line originated from the highest density used for selection. Low density was neither good for selection nor for evaluation and identification of high-yielding cultivars of common bean. There was no significant difference between the mean yield of lines selected at the intermediate and high population densities. The effects of plant density, year, and their interactions were significant for seed yield. 相似文献
14.
Association of isozyme genotypes with agronomic and seed composition traits in soybean 总被引：2，自引：0，他引：2
Summary Two crosses between Glycine max (L.) Merr. and G. soja Sieb. & Zucc. parents were used to study the association between isozyme marker loci and agronomic and seed composition traits in soybean. The parents possessed different alleles at six isozyme loci for Cross 1 (A80-244036 × PI 326581) and at eight isozyme loci for Cross 2 (A81-157007 × PI 342618A). A total of 480 BC2F4:6 lines from the two crosses was evaluated for 13 traits in two environments. Lines were grouped in locus classes from 0 to 5 according to the number of loci homozygous for the G. soja alleles that they possessed. Within each locus class, each isozyme genotype was represented by five random lines.Selection for G. max alleles at the isozyme loci was not effective in recovering the recurrent parent phenotype in either cross. In cross 1, however, BC2F4-derived lines in the 0- or 1- locus class more closely resembled the G. max parent than lines in the 4- or 5- locus classes for most of the agronomic and seed composition traits evaluated. Significant associations were found between particular isozyme genotypes and every trait analyzed. The estimated effect of genes linked to the Pgm1 locus was a delay in maturity of 6.0±3.4 days. In cross 1, the Idh2 locus was associated with a significant effect on linolenic acid content. The percentage of variation accounted for by the models of estimation varied according to the heritability of the trait. The R2 was high (up to 78%) for maturity, lodging, and vining, and low (up to 21%) for seed yield. Most of the variation was associated with the BC2F1 family from which the lines were derived. There was little evidence that digenic epistasis was an important source of variation.Journal Paper No. J-13505 of the Iowa Agric. Home Econ. Exp. Stn., Ames, IA, Project 2475. 相似文献
15.
Summary Recurrent selection programs can be manipulated by varying either the extensiveness of testing used to identify superior lines or the number of intermating generations conducted among the superior lines between cycles of selection. The research was conducted to compare the performance of soybean (Glycine max (L.) Merr.) lines derived from populations developed by recurrent selection for seed yield using a factorial arrangement that combined one or two stages of replicated yield testing to identify superior lines with one or three generations of intermating among the selected lines. The base population AP6, which was used for this evaluation of alternative strategies of recurrent selection, was derived from 40 high-yielding strains of Maturity Groups 0 to IV. For this study, the 40 original parents of AP6 and the lines used as the parents for the most advanced cycle of selections for each of the strategies were evaluated in four Iowa environments. The number of cycles of selection completed for the strategies under evaluation varied from two to five. Strategies with two stages of replicated yield testing to select superior lines resulted in a larger number of high-yielding lines than when only one stage of testing was conducted. A larger number of high-yielding lines was obtained from strategies with one generation of intermating than when three generations were used. With the procedures used for the one-stage and two-stage tests in this study, the results indicated that an appropriate strategy for recurrent selection of seed yield in soybean would involve two stages of replicated yield testing to identify superior lines and one generation of intermating among the selected lines to form a new population.Journal Paper no. J-12025 of the Iowa Agriculture and Home Economics Experiment Station, Projekt 2475, Ames, IA. 相似文献
16.
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. 相似文献
17.
Summary The efficiency of indirect selection for seed yield was compared with direct selection for yield per se in chickpea. A total of 2500 single F2 plants, derived from 50 crosses with 50 plants from each cross, were divided into five sub-populations (SP1 to SP5) of 500 plants each by including 10 plants from each of the 50 crosses. The five sub-populations were advanced upto F6 by exercising 10% selection intensity for four successive generations for number of pods per plant in SP1, number of seeds per pod in SP2, seed weight in SP3, seed yield in SP4 and random selection in SP5. The efficiency of direct and indirect selection for yield was evaluated by comparing groups of 50 F6 lines from each sub-population. SP1 and SP3 F6 lines showed higher mean grain yield than the other three methods. SP1 and SP3 were found to be almost equally efficient in developing F6 lines which were significantly superior to the check. This suggests that indirect selection for yield via pod number and seed weight is more efficient than direct selection for yield. 相似文献
18.
Mateus Figueiredo Santos Tassiano Maxwell Marinho Câmara Gustavo Vitti Moro Emiliano Fernandes Nassau Costa Cláudio Lopes De Souza Jr 《Euphytica》2007,157(1-2):185-194
This research reports responses to selection and changes in general (GCA) and specific (SCA) combining abilities after three
cycles of a modified reciprocal recurrent selection procedure (MRRS) in EPB-4 and EPB-5 maize populations. In the MRRS procedure
a cycle can be completed in 1 or 2 years depending on the availability of winter breeding nurseries. The original and the
three selection cycles of the two populations per se (eight entries) and the partial diallel developed from the crosses between
them (16 entries) were evaluated in six environments. Realized response to selection on the population cross was 7.25% cycle−1 for grain yield, −13.63% cycle−1 for plant lodging, and 11.93% cyle−1 for prolificacy, whereas plant and ear heights remained unchanged. GCA estimates increased with selection cycles for both
populations for grain yield and prolificacy, and decreased for plant lodging, indicating that the frequency of favorable alleles
with additive effects for these traits increased with the MRRS cycles in both populations. SCA estimates increased for grain
yield and prolificacy indicating that the frequency of favorable complementary alleles at loci with non-additive effects in
the reciprocal populations increased with the MRRS cycles. For grain yield, SCA effects increased more than GCA effects with
selection cycles, indicating that MRRS exploited more the non-additive effects than the additive effects for the improvement
of this trait. The overall results showed that the MRRS procedure was highly effective in improving the population cross,
exploiting both GCA and SCA effects. 相似文献
19.
Summary Early testing was evaluated for efficiency as a procedure for selecting among lines for yield (total and marketable fruit number), earliness and fruit quality (shape, color and seedcell size) in 24 sets of lines developed at random from a pickling cucumber (Cucumis sativus L.) population. The advantage of early testing was calculated using the regression of S6 on S1 performance. The amount of effort required in worker-hours and the theoretical gain from selection were also considered in estimating the advantage of early testing. Early testing for specific combining ability and for general combining ability was up to 2.05 times as efficient as late testing for total yield, and up to 2.29 times as efficient as late testing for earliness. Early testing was not efficient for selection for the fruit quality traits measured, nor for inbred performance per se. 相似文献
20.
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