Heterosis and Genetic Parameters for Yield and its Attributes of some Bread Wheat Varietal Crosses at High-N and Low-N Environments

Abstract

Six wheat varieties were single crossed at 2017/18. Six parents and its 15 F1 single-crosses were cultivated under N-normal and N-stress at 2018/19, to study heterosis and the genetic parameters for yield and its components under normal and N-stress. Mean squares of wheat-gentypes, parent, F1-crosses and parent versus cross were highly significant or significant for most of traits under both conditions. The highest desirable heterosis and heterobeltiosis were detected by crosses No. 7 and No.8 for earliness; No.14, No.8 and No.3 for 100-Grain weight; crosses No.8 and No.13 for number of spikelets/spike; crosses No.9, No.7 and No.13 for number of grains per spike; cross No.4 for number of spikes/plant; crosses No.3, No.12 and No.10 for grain yield per plant, therefore, it might be decided that these crosses may be beneficial for enhancing wheat grain-yield programs under low or high N conditions. The median grade of dominance was greater than one for all characters under both conditions, suggesting the importance of over dominance gene effects in the genetics of these traits. Heritability in broad sense (hb.s.) had high values for all traits under both conditions. Lower heritability estimates in narrow sense (h2n.s.) were detected for all the studied traits under both conditions, except each of spikes number /plant, weight of 100-grain and protein % at both conditions which had moderate values of narrow sense heritability, reflecting the part of environmental factors and dominance genes in heirloom scheme of these characters.