DIALLEL ANALYSIS OF SPAD, YIELD COMPONENT AND NITROGEN USE EFFICIENCY OF SOME BREAD WHEAT GENOTYPES UNDER LOW AND HIGH NITROGEN LEVELS

Abstract

Wheat is an extremely essential food crop. It offers a huge wealth of material for genetic analyses due to its broad ecological distribution. Due to ex traordinary production cost and restrain the pollution to the environment, it is imperative to decrease the amount of nitrogen (N) fertilizer used on wheat crops. Therefore, a full diallel cross mating design among 4 bread wheat was determined under low (Nt0, no N fertilizer) and high (Nt15, 150 kg N ha−1 ) N levels for SPAD, some quality and nitrogen use efficiency characters to assess general combining ability (GCA) and specific combining ability (SCA) effects and their interactions with nitrogen levels. The analysis of variance was significant for all the characters which showed a significant variability be tween the two nitrogen levels, except for the starch content. GCA was highly significant effects for SPAD at heading growth stage, SPAD at the anthesis growth stage, thousand kernel weight (TWK) and starch content. While SCA effects were highly sig nificant for grain yield, grain nitrogen yield (GNY), grain nitrogen yield nitrogen use efficiency (gnyNUE) and grain yield nitrogen use efficiency (gyNUE). The GCA / SCA ratio was less than one for grain yield, GNY, gnyNUE and gyNUE. These findings indicate that the non-additive genetic ef fects were more significant than additive gene action and played a key role in these traits. Cultivar 84CZT04 had the best GCA effects for TWK, pro tein content, grain yield, GNY, gnyNUE and gyNUE at low and high N levels.