GENETIC ANALYSIS IN DIALLEL CROSSES OF BREAD WHEAT UNDER HEAT STRESS

Abstract

Present investigation was carried out at the Research Farm and Laboratories of Department of Genetics, Faculty of Agriculture, Ain Shams university, Shoubra El-Khema, Cairo, Egypt, to assess mean performance, heterobeltiosis, combining ability and thermal stress tolerance in bread wheat (Triticum aestivum L.). during the period from 2016 to 2017, in order to evaluate the genetic performance in the field under normal condition for some agronomic traits and in the Genetic laboratories under heat stress. 1.Field experiment: In the 2016/2017 growing season, the seeds of the seven parents [(P1) Gemmiza 9, (P2) Shakha-93, (P3) Sakha 94, (P4) Giza 168, (P5) Jawahir-14, (P6) Acsad 925 and (P7) Bob white] and their 21 F1 hybrids were planted at 15 November 2016 in a randomized complete blocks design (RCBD) with 3 replicates. The experimental plot was one row. Each row was 3 m in length and 25 cm in width. Seeds were spaced at 15 cm within rows, where one plant was left per the hill. There was no previous crop in the summer of 2016. The recommended cultural practices for wheat production were applied throughout the growth period. days to 50% heading, days to maturity, flag leaf area (cm2), plant height (cm), number of spikes / plant, spike length (cm), number of spikelets per spike, Number of kernels /spike, 1000 grain weight (g) and grain yield /plant (g) traits were recorded on a sample of 10 guarded plants of each plot. Estimates of combining ability effects were made estimated by applying Griffing (1956), Method 2 model 1 (one set of F1’s and parents). Percentage of heterosis relative to better parent was estimated.