Breeding measurements for heading date, yield and yield components in wheat using line x tester analysis

摘要

A study was carried out in Egypt during the winter seasons of 2000/01 and 2001/02 to evaluate thirty-five introduced wheat lines which were crossed with four local wheat cultivars, Sids 4, Gemmeiza 9, Giza 168 and Sakha 93, as testers (T1, T2, T3 and T4, respectively) to produce 140 crosses using line x tester to estimate heterosis, combining ability effects and gene effects for heading date, plant height, spike length, number of spikes per plant, number of kernels per spike, 1000-kernel weight andgrain yield per plant. The studied genotypes, i.e parents, parents vs crosses, crosses, lines, testers and lines x testers, exhibited highly significant variance for all the traits except spike length and number of spikes per plant for lines x testers.The results revealed that the additive gene effects were larger than those of the nonadditive and played the major role in the inheritance for all traits, except heading date and plant height. The parental lines 1, 6, 11, 25, 30 and 32 were the best combiners for yield and yield components and might be selected as parental materials for wheat breeding programmes. However, the hybrids L30 x T4 and L32 x T4 had the highest significant heterosis for yield and its components for better parent and specific combining ability effects. Heritability in broad sense (Tb%) was high and exceeded 70 for all traits except for spike length where its value was moderate. However, narrow-sense heritability was high (more than 50%) for plant height, number of spikes per plant, number of kernels per spike, 1000-kernel weight and grain yield per plant and was moderate (30-50%) for heading date and spike length. The highest expected gain expressed as a percentage of the mean was rather high for number of spikes per plant (56.028%) followed by grain yield per plant (54.415%), number of kernels per spike (37.09%), 1000-kernel weight (13.88%), heading date (8.711%), spike length (8.341%) and plant height (8.096%), which showed low genetic gain.