Showing papers on "Diallel cross published in 2009"

A diallel study of yield components and fruit quality in chilli pepper (Capsicum baccatum)

Abstract: The aim of this work was to estimate the general and specific combining ability of peppers by measuring fruit quality and yield traits. This experiment was carried out on the garden field from Universidade Federal de Vicosa (UFV), Minas Gerais State—Brazil. Eight lines of Capsicum baccatum belonging to the UFV Horticultural Germplasm Bank were chosen based on their broad genetic and phenotypical background variation and then they were crossed in a complete diallel way. The F1 seeds of the 56 hybrids and eight parents were planted in the field in a randomized complete block design. The data were submitted to ANOVA and the means were grouped by Scott–Knott test (P ≤ 0.01). Significant variation for fruit quality and yield components was observed among parents and F1 generation. Analysis of variance for the combining ability showed that GCA effects exhibited significant difference and SCA effects of the crosses were significant, except for the height of first bifurcation. For almost all characters both additive and non-additive effects influenced the performance of hybrids.

Combining ability and heterosis for some agronomic traits in crosses of maize.

Abstract: In 2007, five maize inbred lines were crossed in all possible combinations without reciprocals by using a half diallel crosses mating design to obtain 10 single cross. Inbred parents and their F1 single crosses were evaluated through 2008 season to evaluate the role of general and specific combining ability and heterosis for some agronomic traits. Results indicated that mean squares of genotypes were highly significant for all studied traits, i.e., ear diameter, ear length, number of kernels/row, 100-kernel weight, ear yield per plant, grain yield per plant and shelling percentage. General Combining Ability (GCA) and Specific Combining Ability (SCA) mean squares were highly significant for all studied traits. The GCA/SCA ratio was less than unity for all studied traits; this means that these traits are predominantly controlled by non-additive gene action. Significant positive GCA effects were found for all studied traits. Based on GCA estimates, it could be concluded that the best combiners were Rg5 and Rg8 inbred lines for most of studied traits. This result indicated that these inbred lines could be considered as good combiners for improving these traits. Significant positive SCA effects were found for all studied traits. Based on SCA effects, it could be concluded that the best crosses for ear diameter and 100-kernels weigh was G507AxG516; for ear length was G516xRg8; for kernels number/row was G516xG278; for ear yield/plant, grain yield/plant and Shelling percentage was G278xRg5. These crosses could be selected and used in breeding programs for improving these traits. Results showed positive significant heterosis values for all studied traits. The best crosses over both their mid-parents and better-parents for ear diameter and 100-kernel weigh was G507AxG516; for ear length and kernels number/row was G516xG278; for ear yield/plant and grain yield/plant was G278xRg8 and for Shelling percentage was G278xRg5.

Growth and survival of three small abalone Haliotis diversicolor populations and their reciprocal crosses

Abstract: The aquaculture industry of small abalone Haliotis diversicolor in southern China is now close to collapse because of high mortality at the grow-out stage. To examine if survival and growth (shell length increase) could be improved by cross breeding among populations, a 3 × 3 complete diallel cross was conducted among three populations from Japan (A), Taiwan (B) and Vietnam (C). Performances in growth rate and survival at early juvenile, later juvenile and grow-out stages were compared among the six reciprocal cross lines and three parental lines. Magnitude of heterosis for survival and growth varied among cross lines in the three growing stages. As to mid-parent heterosis, HAB was significantly (P<0.01) higher than HAC and HBC at all three growing stages for both growth and survival, and all mid-parent heterosis fell between the two corresponding single-parent heterosis. HAB was 6.84% for shell length and 69.09% for survival at Day 420. Our results of high survival heterosis in line AB and line BA show that crossbreeding between different populations can benefit the small abalone breeding programs and the industry.

Genetic analysis of grain yield, days to flowering and maturity in oilseed rape (Brassica napus L.) using diallel crosses

Abstract: Twenty one F2 progenies derived from a 7×7 diallel crosses along with parents were evaluated for grain yield, flowering and maturity time Due to significant genotypic effects for all traits, genetic analyses were performed on F2 progenies including analyses of combining ability and genetic components The Analysis of variance revealed that both additive and non-additive genetic effects were involved in controlling these traits GCA/SCA ratios were 091 for days to flowering, 095 for days to maturity and 083 for grain yield which indicated that the additive gene effects were more important than non-additive gene effects for all these traits Narrow-sense heritability was high for days to flowering (7312%) and days to maturity (8199%) and low for grain yield (3015%) Heterosis in hybrids seemed to be largely determined by complementary epistasis as well as genetic distance between the parents The spring-type varieties Tower and Regent appeared as the best parents for earliness whereas winter-type varieties DR and Ceres were best parents for high grain yield It could be concluded from the study that S1 recurrent selection would be effective to improve the performance of these genotypes for grain yield, flowering and maturity time The selected S1 lines from each cycle can be used in a pedigree-breeding program to identify superior genotypes

Diallel cross analysis for maturity and yield-related traits in melon (Cucumis melo L.)

Abstract: A complete diallel cross study of six local populations of Iranian melon (Eyvanaki, Abasali, Tashkandi, Hose-sorkh, Mashhadi and Nahavand) and one foreign cultivar (Ananasi) was carried out. We investigated maturity, average weight per fruit, yield and acceptable yield in the pruning conditions over a period of two planting seasons. The analysis of variance for all of the characteristics indicated highly significant differences among genotypes. Additive gene effects were most important with respect to average weight per fruit and yield, while genetic dominance effects mainly controlled fruit maturity and acceptable yield. The reciprocal effects were significant for yield, acceptable yield and fruit maturity. Nahavand and Tashkandi had significant positive general combining ability effects for yield and acceptable yield. Favourable heterosis over the better parent was found for average weight per fruit, yield and acceptable yield. Thus, there is the potential to generate superior cultivars in segregant generation and hybrid production.

Genetic Analysis for Yield Potential and Quality Traits in Maize (Zea mays L.)

Abstract: Grain yield is a complex phenomenon which results from the interaction of various contributing factors highly influenced by environmental variation. Phenotypic selection cannot directly improve the characters in heterozygous crops like maize unless dissected by genetic analysis. Gene action for various quantitative and qualitative traits was explored in a complete set of diallel involving seven elite inbred lines. Variance/Co-variance graphs revealed that the yield potential traits like number of days taken to tasselling, number of days taken to silking, plant height, number of ears per plant, number of kernel rows per ear, number of kernels per row, 100-kernel weight and grain yield per plant were controlled by over dominance type of gene action, while quality traits like protein and oil contents were under the control of partial dominance with additive type of gene action.

Genetic variance components and genetic effects among eleven diverse upland cotton lines and their F2 hybrids.

Abstract: Selecting high yielding upland cotton, Gossypium hirsutum L. lines with improved fiber quality is a primary breeding goal. A diverse set of ten cultivars and one breeding line were crossed in a half diallel. Parents and F2 hybrids were grown in three environments at Mississippi State, MS. Ten agronomic and fiber traits were analyzed by a mixed linear model approach based on the additive-dominance genetic model. Variance component, genetic effects and genetic correlations were calculated. ‘Acala Ultima’ was a desirable general combiner for fiber length, uniformity, strength, micronaire, lint percentage, and boll weight. ‘FiberMax 966’ was a desirable general combiner for fiber length, uniformity, strength, and all agronomic traits. ‘Tamcot Pyramid’ and M240 were poor general combiners for both fiber and agronomic traits. ‘Coker 315’ was a good general combiner for fiber length, uniformity, micronaire, boll weight, boll number, and yield. Heterozygous dominance effects were associated with several crosses, which suggest their use as hybrids.

Genetic distances between popcorn populations based on molecular markers and correlations with heterosis estimates made by diallel analysis of hybrids.

Abstract: Diallel analysis was used to obtain information on com­bining ability, heterosis, estimates of genetic distances by random amplified polymorphic DNA (RAPD) and on their correlations with heterosis, for the popcorn varieties RS 20, UNB2, CMS 43, CMS 42, Zelia, UEM J1, UEM M2, Beija-Flor, and Vicosa, which were crossed to obtain all possible combinations, without reciprocals. The genitors and the 36 F1 hybrids were evaluated in field trials in Maringa during two growing seasons in a randomized complete block design with three replications. Based on the results, strategies for further studies were developed, including the construction of composites by joining varieties with high general combining ability for grain yield (UNB2 and CMS 42) with those with high general combining ability for popping expan­sion (Zelia, RS 20 and UEM M2). Based on the RAPD markers, UEM J1 and Zelia were the most genetically distant and RS 20 and UNB2 were the most similar. The low correlation between heterosis and genet­ic distances may be explained by the random dispersion of the RAPD markers, which were insufficient for the exploitation of the popcorn genome. We concluded that an association between genetic dissimilar­ity and heterosis based only on genetic distance is not expected without considering the effect of dominant loci. Diallel analysis was used to obtain information on com­bining ability, heterosis, estimates of genetic distances by random amplified polymorphic DNA (RAPD) and on their correlations with heterosis, for the popcorn varieties RS 20, UNB2, CMS 43, CMS 42, Zelia, UEM J1, UEM M2, Beija-Flor, and Vicosa, which were crossed to obtain all possible combinations, without reciprocals. The genitors and the 36 F1 hybrids were evaluated in field trials in Maringa during two growing seasons in a randomized complete block design with three replications. Based on the results, strategies for further studies were developed, including the construction of composites by joining varieties with high general combining ability for grain yield (UNB2 and CMS 42) with those with high general combining ability for popping expan­sion (Zelia, RS 20 and UEM M2). Based on the RAPD markers, UEM J1 and Zelia were the most genetically distant and RS 20 and UNB2 were the most similar. The low correlation between heterosis and genet­ic distances may be explained by the random dispersion of the RAPD markers, which were insufficient for the exploitation of the popcorn genome. We concluded that an association between genetic dissimilar­ity and heterosis based only on genetic distance is not expected without considering the effect of dominant loci.

Combining ability and heterosis for yield contributing traits in upland cotton (gossypium hirsutum l.)

Abstract: A 4x4 complete diallel crosses between Sadori, CRIS-134, Sohni and CIM-448 was designed in F1 generation to estimate the general and specific combining abilities of genotypes and to determine the degree and direction of heterosis and selection of promising recombinants for future breeding programme. The experiment was conducted in RCBD in three replication at experimental farm of Nuclear Institute of Agriculture, Tando Jam during 2005-06 for the traits plant height, sympodia/plant, bolls/plant and seed cotton yield/plant. The results of GCA showed that the variety Sadori proved to be best general combiner for plant height, number of bolls/ plant and seed cotton yield while the crosses Sadori x CIM-448 and Sadori x CRIS-134 exhibited higher SCA effects for boll number/plant. All the crosses showed positive magnitude of heterosis over mid and better parental means for plant height. The crosses Sadori x CIM-448 followed by CIM-448 x Sohni exhibited positively higher heterosis and heterobeltiosis for number of bolls /plant and seed cotton yield/plant.

Legacy study of cotton seed traits in upland cotton using Griffing's combining ability model.

Abstract: Combining ability was studied for identification of potential cultivars and hybrids, and the nature of gene action involved for inheritance of cottonseed traits and oil content % in a 6x6 diallel cross in upland cotton (Gossypium hirsutum L.) during 2003-2005. Analysis of variance revealed highly significant (p≤0.01) differences among the genotypes for all the traits. Combining ability studies showed that the mean squares due to general combining ability (GCA) and specific combining ability (SCA) were mostly significant in F1 and F2 generations. Genetic components of variances due to GCA and SCA revealed that most of the traits were controlled by additive type of gene action in both generations because of greater GCA variances. However, seeds per boll and cottonseed oil % in F1 generation gained preponderance of SCA variances having non-additive type of gene action. Cultivar CIM-1100 was found as leading general combiner in combination with other cultivars BH-36 and CIM-240, FH-682 and CRIS-9, and their hybrids (CIM-1100 x BH-36, CIM-240 x CIM-1100, FH-682 x BH-36, CIM-1100 x FH-682 & CIM-1100 x CRIS-9) showed prominent SCA and renowned mean performance for seeds per boll, seed index and cottonseed oil content %. Therefore, involvement of CIM-1100 in most of the hybrids resulted in the synthesis of superior genotypes for all the traits.

Stability of combining ability effects in maize hybrids

Abstract: General and specific combining ability effects are important indicators in a maize (Zea mays L.) breeding program aiming hybrid development. The objectives of the present study were to estimate the general (GCA) and specific combining abilities (SCA) effects of commercial maize hybrids using a complete diallel scheme and to assess the stabilities of these estimates. Fifty-five entries were assessed; ten commercial single-crosses and all possible double-crosses. The experiments were carried out in 12 environments in the 2005/06 growing season. A randomized complete block design was used with three replications per environment. Ear yield was evaluated, corrected to 13% of moisture content. The combined diallel analysis involving all environments was performed and the stability of general and specific combining ability effects was investigated. The underlying nonparametric statistics evaluated the contribution of each effect to the genotype by environment interaction. Non-additive effects were more important for this set of hybrids than the additive effects. It was possible to select parents with high stability for combining ability and with high GCA.

Combining ability studies for physiological and grain yield traits in maize at two temperature regimes.

Abstract: The F1 generation obtained from a 6×6 diallel cross was evaluated for combining ability effects at normal and high temperature regimes for various physiological and grain yield parameters. The mean squares due to genotypes, general combining ability (GCA), specific combining ability (SCA) and reciprocal effects were highly significant for all the traits at both temperature regimes while GCA effects were non–significant for stomatal conductance and transpiration rate at high temperature. The GCA: SCA variance ratio exhibited that all traits were controlled by the non-additive genes except for growing degree-days to 50% maturity that was predominantly under the control of additive genes at both temperature regimes. The inbred line 935006 was found to be the best general combiner with better mean performance for grain yield plant -1 with lesser growing degree days to 50% silking growing degree days to 50% physiological maturity and higher turgor potential at normal and high temperature regimes. The best single cross hybrid was 935006 × R2304-2 and its reciprocal followed by F165-2-4 × R2304-2 and F165-2-4 × 935006 for good specific combining ability, reciprocal effects, better grain yield plant -1 and some other desirable traits.

Diallel analysis of leaf disease resistance in inbred Brazilian popcorn cultivars.

Abstract: We estimated general and specific combining abilities and examined resistance to northern leaf blight (Exserohilum turcicum) and to gray leaf spot (Cercospora zeae-maydis) in a set of nine inbred popcorn lines. These inbreds were crossed in a complete diallel scheme without reciprocals, which produced 36 F(1) hybrids. Two experiments with a square lattice design and three replications were conducted during the 2008/2009 crop season, in Maringa, PR, Brazil. The severity of northern leaf blight and gray leaf spot was assessed under natural infestation conditions. Data were examined by individual and joint analysis of variance. Individual and joint Griffing's diallel analyses were carried out for adjusted means. General combining ability and specific combining ability were significant (P < 0.10) by the F-test for northern leaf blight and gray leaf spot infestation levels. This denotes that additive and non-additive gene effects both contributed to resistance to these diseases, but that the additive gene effects were more important. Among the inbred lines, P(8) and P(9) gave the highest resistance to northern leaf blight, and P(3) and P(4.3) gave the highest resistance to gray leaf spot. The hybrids P(7.4) x P(8) and P(4.3) x P(9) could be exploited by reciprocal recurrent selection to provide genotypes with both northern leaf blight and gray leaf spot resistance. Significant interaction between general combining ability and crop season (P < 0.10) denotes the importance of environment, even though the disease levels in the hybrids were quite consistent.

Capacidade combinatória entre híbridos simples de milho em dialelo circulante

Abstract: Estimatives of the general combining ability (CGA) and specific combining ability (SCA) among eleven commercial maize hybrids were obtained in this study. Single-cross hybrids AS 1550, DK B214, DK B215, DK B330, Dow 2B150, Dow 8460, P 30F33, P 30F53, P 30P70, Penta and Premium Flex were intercrossed in a circulant diallel scheme with p=11 (eleven parents) and s=8 (crossed 8 to 8) to obtain 44 double hybrids. These genotypes were evaluated in randomized block design with three replications. Two experiments were carried out in Center-South Parana State, in Guarapuava and Goioxim, Brazil. The yield, plant height and ear height were obtained and submitted to diallel analysis. There were significant differences between localities and between diallel hybrids for both traits. Significant differences were observed for localities x diallel hybrids interaction for grain yield. Significant differences were detected for GCA in all characteristics and for SCA only in yield. Parents Penta, P 30F53 and Dow 8460 were outstanding for CGA values in yield, and parent AS 1550 in plant height and ear height. The best hybrid combination was Penta x P 30F53, since it showed the highest yield, high SCA value and both parents presented the highest GCA estimative. The hybrid P 30F53 was parent of three among four of the most productive double hybrids. It is possible to obtain good populations from the commercial cultivars that were outstanding because of GCA and SCA estimatives in hybrid combinations.

Genetic analysis of grain yield and some agronomic traits in hulless barley

Abstract: The choice of an efficient breeding procedure depends to a large extent on the knowledge of the genetic system controlling the character to be selected. An eight-parent diallel, involving hulless barley varieties ICNBF-582, ICB-102607, ICNBF93-328, SB91925, ICNBF8-613, BBSC congana, Petuina2 and ICNBF93-369, was evaluated to determine the genetic parameters contributing to plant height, days to maturity, number of tillers, number of grains per spike and grain yield per plant. Furthermore, generation mean and variance analysis was carried out on six generations (P1, P2, F1, F2, BC1 and BC2) derived from the cross ICNBF93-369ICNBF-582 and SB91925ICB-102607 to complement the genetic information obtained from the diallel analysis. Wr/Vr graph in diallel analysis and average degree of dominance together with narrow-sense heritability values in both experiments revalued additive gene effects for plant height, number of tillers and days to maturity and over-dominance gene action for number of grains per spike.Although in cross ICNBF93-369ICNBF-582 the dominance effects had a greater share, the additive effects in diallel analysis and cross SB91925ICB-102607 played major role in the inheritance of grain yield per plant, since narrow-sense heritability of this trait was low. It can therefore be concluded that direct improvement of this trait is somehow problematic because environmental factors contribute greatly in the control of the trait. Key words: Hulless barley, diallel, generation mean analysis, gene effects, agronomic traits.

Crossbreeding parameters for growth and feed consumption traits from a five diallel mating scheme in rabbits.

Abstract: Twenty-five genetic groups of young rabbits originated from a diallel-crossbreeding scheme among 5 selected lines: 3 maternal and 2 terminal sire lines belonging to 2 Spanish research institutions. A sample of 2,773 young rabbits from 525 litters was controlled during the fattening period lasting from 5 to 9 wk. Growth and feed consumption traits were evaluated throughout different biweekly batches. A Bayesian approach was used for inference from an animal model with common litter effects. On average, genetic groups coming from lines selected for growth rate were heavier (+58.9 g at 32 d and +315.5 g at 60 d), had greater growth rate (9.24 and 8.15 g/d from individual or cage analysis, respectively) and feed intake (+13.24 g/d), and showed better feed conversion ratio (-0.21 g of intake/g of gain), than the genetic groups originated from crosses among lines selected for litter size. Crossbreeding parameters were estimated from the samples of the marginal posterior distribution of the genetic group effect according to the Dickerson model. Maternal genetic and individual heterosis effects were null or very low. Direct genetic effects mainly regulated the expression of growth traits.

Combining ability of wheat genotypes in two models of diallel analyses.

Abstract: Diallel analyses are commonly used for the estimate of population genetic effects. Different models can be used, with a direct effect on the inferences. The objective of this study was to determine and compare two diallel analysis models, fixed and random, regarding the combining effects among six wheat genotypes. The experiment was conducted in the county of Capao do Leao/RS in the year 2006. Six wheat genotypes were used that were used for artificial crosses according to a complete diallel model without reciprocals, resulting in 15 hybrid combinations. The data were subjected to diallel analyses according to model 2 of Griffing (fixed) and BLUP (random). The results show that both diallel models indicate similar general combining ability effects. On the other hand, for the specific combining ability , the data must be used with caution, considering the two models simultaneously .

Genetic studies of yield related traits in mungbean (Vigna radiata L. Wilczek)

Abstract: A full diallel mating system involving eight divergent parents selected from a germplasm pool of 55 mungbean genotypes was used to determine the inheritance of yield related traits such as grain yield per plant, total dry matter, and harvest index. All traits displayed significant (P D for grain yield in F1 and harvest index in F2 generation depicted the preponderance of dominant genes in their genetic control which, thus it was recommended that selection followed by hybridization in early generations was a suitable breeding method for progress in these traits. Conversely, greater value of D over H1 demonstrated additive nature of genes for grain yield in F2, harvest index in F1 and total dry matter in both generations, which advocated the utilization of pedigree and full/half sib selection for improvement of these parameters. Grain yield in F1 and harvest index in F2 generation exhibited moderate narrow sense heritability, while grain yield in F2, harvest index in F1 and total dry matter in both generations had higher heritability (h 2 n. s. >0.60).

Membrane Thermal Stability at Different Developmental Stages of Spring Wheat Genotypes and Their Diallel Cross Populations

Abstract: Membrane thermal stability (MTS) can be a significant selection criterion for heat stress tolerance. MTS is determined by measuring of electirical conductivity of aquause phase in which leaf tissue exposure to high temperature. This research was conducted to investigate the membrane stability assay measured by two different methods, namely MTS and relative injury (RI). The second objective of this experiment was to determine the effects of different growth stages of four spring wheat parents and their six half F2 diallel cross progenies grown in the field on membrane stability. Measurements were taken at different growth stages (seedling, stem elongation and early milk). The MTS and RI assays gave similar results at the three different growth stages. However, growth stages significantly affected the MTS and RI values of genotypes. Membrane stability parameters of genotypes decreased during the later developmental stages. Specific combining ability effects were superior to general combining ability effect for all measurements, indicating that membrane thermal stability was mediated mainly by non-additive gene actions. Membrane stability of flag leaf at the early milk stage was significantly correlated with grain yield. The parent of Genc 99 and 84CZT04 had low yield potential, whereas Chil's and Seri 82 had high yield potential. Grain yield, spike yield and kernel weight of F 2 population were found higher than their parents. These results suggest that genetic variation among genotypes for membrane stability can be utilized in wheat breeding in heat-stressed environments.

Diallel analysis of sugar composition of 10 vegetable soybean lines

Abstract: Few studies have evaluated vegetable soybean for sugar content at the green pod stage. Information on combining ability and type of gene action that governs inheritance of seed traits can help breeders to select suitable parents and devise an appropriate breeding strategy. Ten vegetable soybean accessions were crossed in a complete diallel mating design. Parent lines and F 2 and F 3 progenies were evaluated for two nutritional components. In this study, both general and specific combining ability and reciprocal effects were significant for sucrose and total sugar. Cultivars 'Kanrich', 'Pella', 'Verde' and V81-1603 had good general combining ability for high sucrose. In general, high sucrose content was observed in progeny of the early maturity group genotypes 'Kanrich', 'Pella' and 'Verde'. The best combiners for high total sugar content were 'Verde', V81-1603 and PI 399055. These genotypes could serve as genetic sources in a vegetable soybean breeding programme.

COMBINING ABILITY ESTIMATES OF TOMATO (Solanum lycopersicum) IN LATE SUMMER

Abstract: Combining ability effects were estimated for yield, yield components and plant height in a 8 x 8 diallel analysis excluding reciprocals. The variances for general combining ability (GCA) and specific combining ability (SCA) were highly significant indicating the presence of additive as well as non-additive gene effects in the traits studied. The relative magnitude of these variances indicated that additive gene effects were more prominent for all the characters. The tomato genotype P1 proved to be the best general combiner for yield followed by P2. In general, the cross P1 x P3 followed by cross P4 x P6 proved better for yield per plant and also for number of fruits per plant, individual fruit weight and days to 50% flowering.

Combining ability analysis across environments for some traits in dry bean ( Phaseolus vulgaris L.) under low and high soil phosphorus conditions

Abstract: Dry bean (Phaseolus vulgaris L.) is an important grain legume for small-scale farmers in eastern Africa who nonetheless, grow beans with limited phosphorus (P) fertilizer supply or none at all. Phosphorus rank second, after nitrogen (N), as the most limiting soil nutrient in bean production in East African soils. This study was conducted to determine combining ability for five polygenic traits in the red mottled, large seeded bean market class, under low and high soil P conditions and two locations. Three parents tolerant to low soil P were hybridized with five well adapted, but non-low P tolerant lines in a diallel mating scheme. The resulting 28 F1 hybrids were evaluated in a randomized complete block design with three replications, under low and high soil P conditions at two sites. There were highly significant (P ≤ 0.001) differences among the genotypes for all the traits under all the study conditions. The GCA mean squares were highly significant (P ≤ 0.001) for these traits, indicating importance of additive effects for both study conditions and sites. The GCA × Environment and SCA × Environment were significant for all the parameters and test conditions. CAL143 had positive GCA effects that were significant; except for 100-seed weight under P stress; for all the traits and under all the study conditions. The negative GCA effects for the none P tolerant parents indicate that they impacted positively in imparting earliness.

Morphological, pedigree, and molecular distances and their association with hybrid wheat performance

Abstract: The objectives of this work were to estimate the genetic distance among wheat genotypes using morphological, pedigree, molecular, and combined morphological and molecular measures, to determine the correlations between these measures, and to evaluate the combining ability of the genotypes. Three generations and two planting designs were studied. Six wheat genotypes were crossed using a diallel design. The F1, F2 and F3generations were evaluated in the field, in the crop seasons of 2003, 2004 and 2005, under spaced plant and full-row planting designs. The estimated general and specific combining abilities of tested hybrids were influenced both by the generation and the planting design. The correlation coefficients among the distance measures and between these measures and genotype performances of different generations for the two planting designs were low to moderate. In order to obtain a more precise estimate of the genetic distance among cultivars and its association with the hybrid performance, more than one generation, planting design, and genetic distance estimation technique should be employed.

Study of fiber quality traits in upland cotton using additive-dominance model

Abstract: Diallel analysis was studied in F1 and F2 hybrids by crossing six upland cotton cultivars (CIM- 109, CIM-240, CIM-1100, FH-682, BH-36 and CRIS-9) following Hayman's diallel approach using Mather's concept of D, H components of variation for additive and dominance genetic variances, respectively. The objectives were to study the additive-dominance model, nature of gene action, heritability and genetic gain in F1 and F2 hybrids and mean performance of the selections (made in F2 population) in advanced segregating generations (F3, F4 and F5) in upland cotton. Genotypes mean values differed significantly for all the fiber quality traits. Additive-dominance model was adequate for fiber length, fiber fineness, and uniformity ratio, while showed partially adequate for fiber strength in F1 generation. In F2s, fiber fineness showed the adequate data, while other three traits manifested partial adequacy. Additive component (D) was found significant for all the traits in F1 and F2 generations. Dominance components (H1, H2) were also significant for all the traits in F1s except the fiber fineness, while were insignificant for all the traits in F2 generation. In F1s the additive gene action was somewhat partial, while in F2s all the traits were controlled by additive gene action as confirmed by average degree of dominance (√H1/D

Genetic basis of some quantitative traits in upland cotton (Gossypium hirsutm L.).

Abstract: Five cotton cultivars were crossed in a complete diallel to study the inheritance of different polygenic traits. Genotypic differences were found to be significant (P<0.01) for all the characters. Adequacy tests disclosed that data of all the parameters were fully adequate for genetic analysis except bolls per plant, staple length, fibre strength, and fibre fineness, which was partially or not adequate. Additive component of genotypic variation (D) was significant and predominant for plant height, sympodia per plant, staple length and fibre strength, while dominance effects (H 1 and H 2) were main controlling factors for of monopodia per plant, number of bolls, lint percentage and seed cotton yield. More dominant genes were revealed in the parents for sympodia per plant, lint percentage and seed cotton yield. The values of H 2/4H 1 demonstrated asymmetrical and unequal distribution of dominant genes in the parents for all characters. Plant height, sympodia per plant, staple length and fibre strength exhibited high narrow sense heritability (h 2 n.s) due to the presence of additive gene action, whereas, monopodia per plant, number of bolls, lint percentage and seed cotton yield possessed low heritability. The genetic analysis suggested that plant height, sympodia per plant, staple length and fibre strength could be improved through sib family, pedigree and progeny selection, while exploitation of heterosis would be necessary to attain the genetic advancement in monopodia per plant, number of bolls, lint percentage and seed cotton yield.