Performance and Stability of Some Durum Wheat Genotypes under Different Sowing Dates and Nitrogen Fertilizer Levels

摘要

The present study was carried out at Shandaweel Agricultural Research Station, Agricultural Research Center, Egypt. Eight durum wheat genotypes of diverse origin were evaluated under 12 environments, which are a combination between three sowing dates,i.e., 20th November, 10th December and 30th December under two levels of nitrogen fertilizer, i.e., 50 and 75 kg N/fed during two winter growing seasons of 2015/2016 and 2016/2017. The combined analysis of variance revealed high significant differencesamong environments, genotypes as well as genotype x environment interaction for six studied traits i.e., days to 50% heading, plant height, number of spikes/m2, number of kernels/spike, 1000-kernel weight and grain yield/fed. The results showed that sowing at the favorable date (20th November) using 75 kg/fed nitrogen fertilizer increased all studied traits. The joint regression analysis of variance for the studied traits showed high significant mean squares due to environment + genotype * environment interactions revealing that genotypes considerably interacted with the environmental conditions. The mean squares due to G x E (linear) were found to be significant for all studied traits, except for days to heading and 1000-kernel weight which reveals genetic variability among genotypes for linear response to varying environments. Stability parameters (bi and S~d) revealed that six genotypes were stable for days to heading, six for plant height, three for number of spikes/m7', three for number of kernels/spike and six for 1000-kernel weight. Five out of the eight studied genotypes, i.e., Sohag 5, line 2, line 3, line 4 and line 5 showed non-significant deviation from regression and their regression coefficient values were close to unity which are classified as stable genotypes for grain yield. Two genotypes had grain yield higher than the grand mean (Sohage 5 and Line 4) and could be considered the most adapted genotypes.