Genetic analysis, heterosis and character association studies in bread wheat (Triticum aestivum L.)

Abstract

The present investigation was carried out with 17 parents and 52 Fı‟s developed from line x tester mating design. The parental lines (13 lines and 4 testers) were grown during rabi, 2015-2016 and 52 cross combinations among lines and testers were made and the seeds of parental lines and 52 crosses were procured. The parents and F1s were evaluated in a Randomized Completely Block Design in three replications at Crop Research Centre (Chirodi Block) of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (U.P.) during rabi, 2016-17. The observations were recorded for eighteen quantitative characters viz; days to 50 % flowering, days to maturity, plant height (cm), spike length (cm), spikelets per spike, productive tillers per plant, grains per spike, flag leaf area (cm2), biological yield per plant (g), grain yield per plant (g), harvest index (%), 1000 weight (g), gluten content (%), ash content (%), and phenol colour reaction (grading) and data of these fifteen traits were subjected to statistical and biometrical analysis except for phenol colour reaction, to find out analysis of variance, combining ability variance and effects, estimates of heritability, genetics advance in percent of mean, correlation coefficient, path coefficient and extent of heterosis. Data on phenol colour reaction was recorded in five grades black, dark brown, light brown, light colour on edge and no colour. Parents and crosses were grouped into three categories. Analysis of variance (ANOVA) revealed that a wide amount of variability among the genotypes were present for all the traits except ash content under study. Estimates of phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV) for all the traits, but little differences were recorded between PCV and corresponding GCV values for all the traits, which indicated that there was not much influence of environment in the expression of the traits, under study. High estimates of heritability (>30 %) in narrow sense were observed for plant height, days to maturity, flag leaf area, spikelets per spike and days to 50 % flowering, while moderate heritability estimates were recorded for eight characters viz; 1000 weight, harvest content, gluten content, grains per spike, grain yield per plant, biological yield per plant, spike length and productive tillers per plant. However, one character like, ash content was showing low heritability % in narrow sense. High genetic advance in % of mean were found for grain yield per plant followed by plant height and harvest index. High heritability (narrow sense) coupled with high genetic advance in percent of mean was observed for plant height and high heritability coupled with moderate genetic advance in percent of mean was observed for flag leaf area, indicated that there is least influence of environment in expression of this trait and selection of desirable plants could be easily made on the basis of this character. Moderate heritability coupled with high genetic advance were recorded for grain yield per plant and harvest index, this indicated that these traits may be relied upon while selecting the genotypes for improvement in wheat. Analysis of variance for combining ability revealed that variance gca among female lines was found highly significant for five traits viz; days to 50 % flowering, days to maturity, plant height, flag leaf area, spikelets per spike, and for two traits namely 1000 weight and gluten content it was found only significant, while variance gca among males (testers) was found non-significant for all the traits. However, variance sca among crosses due to interaction between females x males (F1s) was found to be highly significant for 12 characters viz days to 50 % flowering, days to maturity, plant height, flag leaf area, spikelets per spike, productive tillers per plant, grains per spike, biological yield per plant, grain yield per plant, harvest index, 1000 weight and gluten content under study. These findings indicated that both the additive and non-additive gene actions played a predominance role in expression of the characters under study hence, appropriate breeding strategies could be adopted such as pedigree selection, heterosis breeding, biparental mating, reciprocal recurrent selection, while making improvement in wheat crop. None of parent was found to be a good general combiner for all the traits under the investigation. However, among the parental material K-607, HUW-658, HD-3076, HD-3095, K-9107, PBW-533 and DBW-71 were found to be good general combiners for grain yield and other yield components. HD-3076 and K-802 for ash content, while HD-2864, HD-3095 and PBW-984 for gluten content. These parents may be incorporated in cross breeding programmes under pedigree method or any other suitable breeding method for self-pollinated crop like wheat. However, on the basis of overall performance parents UP- 2523, K-9423, K-607, DBW-71, PBW-533, K-6525, HUW-658 and HD-2864 for gluten content, ash content and phenol colour reaction, which may be involved in corresponding in per se performance of grain yield for improvement in quality including chapati quality in wheat. Out of fifteen characters including grain yield per plant, gluten content, ash content and phenol colour reaction the parents RAJ- 4246, MP-4010, K-9267, HD-3095, HD-3076, UP-2523, PBW-984, K-9423, K-607, DBW-71, PBW- 533, K-6525, HUW-658, HD-2864, K-802, K-9434 and K-9107 were good general combiners which may be exploited under cross breeding followed by pedigree selection for improvement in quality of wheat. These parents could also be involved in crossing programme followed by pedigree selection for improving yield and quality traits and for having broad genetic base in wheat. Cross combinations HD- 3095 x PBW-533, K-9434 x K-9267, MP-4010 x K-9267, K-802 x DBW-71, K-9107 x K-9423, HD- 3095 x K-9267, K-607 x PBW-533, HD-3076 x K-9423, K-802 x PBW-533 and HD-3076 x PBW-533 showed highly significant sca effects along with good per se performance for grain yield per plant, and also for some other important yield and quality components. These cross combinations may be exploited in heterosis breeding programme for better improvement of yield and quality in wheat crop. Grain yield per plant grain yield per plant exhibited highly significant and positive correlation with harvest index, biological yield per plant, grain per spike, days to 50 % flowering, spikelets per spike and spike length, while with gluten content and productive tillers per plant revealed positive significant and plant height expressed negatively significant. Thus, it can be inferred that by improving these characters either alone or in combination the yield in wheat may be improved. Genotypic and phenotypic path coefficient revealed that harvest index and biological yield per plant had high (0.30 to 1.00) direct effect on grain yield, therefore, direct selection for these two traits would be effective for further yield improvement in wheat genotypes. Genotypic path coefficient revealed that grain yield per plant had very high (>1) negative direct effect while, harvest index had very high (>1) positive and direct effect on gluten content, so direct selection of genotypes for gluten content through these characters may be effective. Fifteen hybrids were considered as superior F1 hybrids where the significant heterosis (%) over economic parent (DBW-71) was observed in range of 51.08 % to 72.59 % for grain yield. In the heterobeltiosis, fifteen crosses were shorted out where significant heterosis (%) was recorded in the range of 28.23 % to 52.95 % for grain yield. By exploiting these cross combinations through heterosis breeding programme will lead in development of promising hybrid population for high productivity in wheat.