Influence of Low-N Stress, Genotype and Their Interaction on Grain Yield and Quality Traits of F1 and F2 Diallel Crosses of Wheat (Triticum AestivumL)
Abstract
Developing high yielding varieties of bread wheat under low soil-N conditions is an important goal for
plant breeder in order to overcome the negative impacts of using high rates of N fertilizers. This will lead to a
significant reduction in nitrogen fertilizer use. The objective of this investigation was to study the effects of low-N
environment (E), genotype (G) and G x E interaction on grain yield and quality traits of wheat F1 and F2 diallel
crosses and their contrasting parents in N use efficiency. Genetic materials were evaluated at two seasons
(2007/2008 and 2008/2009) in a split-plot design with lattice arrangement, using three replications. Main plots were
assigned to N levels (0 and 75 kg N/fed), while sup-plots were devoted to genotypes. Data were analyzed across the
two seasons. Low-N caused significant reductions in all studied grain yield components and grain protein content
(GPC) in parents, F1's and F2's. The lowest reduction occurred in harvest index (HI), while spikes/plant (SPP)
showed the greatest reduction, indicating that SPP is the most determinant component of GYPP. The first three
parents L25, L26 and L27 showed significantly higher means than the second three parents Gem7, Gem 9 and
Gz168 for most studied grain yield components and GPC trait. The F1 and F2 crosses involving one or more of the
first three parents showed higher values of one or more of grain yield component traits than crosses that involved
parents of the second group. In general, F1 crosses showed higher means for all studied grain yield and quality traits
than their parents. The rank of crosses in F1 and F2 generation for most studied traits was changed from one
environment (N-level) to another, indicating a significant G x N interaction. Some F2- progenies under N-limited
environment exhibited higher values of GYPP and HI, suggesting transgressive effects in these characteristics, and
that selection practiced in such F2 populations could be effective in developing low-N tolerant genotypes.
