Parents’ Performance and F1 Crosses For Several Bread Wheat Cultivars Under Varying Levels of Nitrogen Fertilization

Abstract

Six bread wheat varieties representing different traits were crossed in a half-diallel in 2017/2018 season. The 6 parents and its 15 F1 crosses were evaluated under normal and N-stress conditions in 2018/2019 season, to study the mean performance and the combining ability for earliness and morpho-physiological traits and biomass yield of wheat under normal and N-stress conditions. Mean squares of genotypes, parents, crosses, and parents versus crosses were significant or highly significant for most of the studied traits and biological yield under both conditions, reflecting a sort of heterosis for these characters. Mean squares of GCA and SCA were significant or highly significant for most of the studied traits under both conditions, indicating the presence of both additive and non-additive types of genes in the genetic system controlling these traits. The best general combiners were P1 (Giza 168) and P2 (Sakha 94) at both conditions, P3 (Shandweel 1) at N-stress, and P4 (Gemmeiza 11) at normal condition for earliness and P6 (Misr 1) at both conditions and P5 (Sids 12) at N-stress and P3 (Shandweel 1) at normal condition for biomass yield plant-1. The best cross combinations were crosses No.3 (P1xP4), No.5 (P1xP6), No.6 (P2xP3), No.7 (P1xP2), No.8 (P2xP5) and No.11 (P3xP5) under N-stress for earliness; and crosses No.3 (P1xP4), No.7 (P2xP4), No.8 (P2xP5), No.12 (P3xP6), No.14 (P4xP6) and No.15 (P5xP6) at both conditions, and cross No.2 (P1xP3) under N-stress for biomass yield plant-1.