Heterosis and Combining Ability Studies for Yield Components in Wheat (Triticum Aestivum L.)

Abstract

Thesis Title: Heterosis and combining ability studies for yield components in wheat (Triticum aestivum L) The present investigation on Heterosis and combining ability studies f.lr yield components in wheat (Triticum aestivum L.) was carried out to assess the genetic information on nature of gene action, combining ability, heterosis and selection with ten diverse parents and their 45 F1s at Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (U.P.) during rabi season of2012- 13 and 2013-14 in randomized block design with three replication parameters under normal condition. The "F" test for the experiment indicated that variance due to treatments were highly significant for all the fifteen traits. Parents vs. hybrid revealed high significant differences for plant height, peduncle length, spike length, 1000-grain weight, biological yield per plant, grain yield per plant, gluten content, ash content and protein content. The crosses also showed significant differences for all the character under study indicating sufficient variability are parent among the materials give ample scope for selection. The analysis of variance for combining ability revealed that general combining ability and specific combining ability variances were found highly significant for all the characters except number of grains per spike, indicating the role of additive and non additive gene actions in the inheritance of these characters. It is suggested that these traits can be improved through high biparental mating and recurrent selection methods. The genotypes, K 612, HUW 648, HUW 658, WCW 95-1 and N\V 4081 exhibited significant gca effects in desirable direction with good per se performanre for 5-7 traits out of fifteen traits related to grain yield which is used for exploiting additive type of gene action (fixable) for which, selection may be effective in segregating generation for the development of best genotype in respect to grain yield in wheat. On the basis of specific combining ability effects, six crosses viz., K 612 X NW 4035, HU\V 648 X HUW 658, K 612 X WCW 95-1, HUW 658 X K 307 and HUW 648 X K 307 were found as best specific crosses for grain yield per plant. All the desirable specific combiners for different traits involved either high x high or high x low or low x low general combiners. For grain yield per plant, best specific cross combinations were of high x low or low x low category. The high heritability (broad sense) coupled with high genetic advance (as % of mean) was found for plant height followed by peduncle length, Spike length, number of grains per spike, I 000-grain weight, biological yield per plant, grain yield per plant, gluten content, ash content and protein content and high heritability coupled with moderate genetic advance observed for days to 50% flowering, number of productive tillers per plant, days to maturity and harvest index, could be used as direct selection parameters for yield improvement. · Grain yield per plant had positive and highly signilicant correlation with biological yield per plant, number of productive tillers per plant, harvest index and number of spikelets per spike both at genotypic and phenotypic level of significance. These traits are used as selection criteria for the improvement in yield. Path coefficient at phenotypic level recorded highest direct positive effect on grain yield pe~: plant with biological yield per plant followed by harvest index and number of spikelets per spike exerted very high and positive direct effect on grain yield per plant while days to maturity, number of productive tillers per plant, ash content, number of grains per spike, spike length and gluten content. Five crosses vi= K 612 x NW 4035, HUW 648 x HUW 658, HUW 648 x NW 4035, K 612 x NW 4081 and K 612 x WCW 95-1 showed positive and significant heterosis more than 11% for grain yield over better parent. These crosses may be exploited through heterosis breeding for improvement in grain yield in wheat. fn the present investigation, both additive and nonadditive genetic variances played important role in the inheritance of almost all the characters studied. For exploitation of both additive and non additive components of variation, present material may be handled through pedigree method, reciprocal recurrent selection or biparental mating may be adopted for obtaining superior segregates and high yielding genotypes in wheat.