GENETIC ANALYSIS OF EARLINESS COMPONENTS IN SOME BREAD WHEAT GENOTYPES

Abstract

The main objectives of this investigation were to study the inheritance of earliness traits in wheat, (Triticum aestivum L.) also to evaluate and study some early and late mature parents and their resulted crosses. This investigation included eight bread wheat parental genotypes differed in their earliness components. Half diallel cross was made between these genotypes. The eight parents and their 28 F1 crosses were planted in two sowing dates, early and normal. The collected data were analyzed using Griffing 1956 procedure, Method 2, model 1.The collected data of this experiment were days to first node emergence, days to booting, days to heading, days to anthesis, days to maturity, grain filling period and grain filling rate. Mean performance of most earliness components was low at early sowing date comparing with those at normal one for most genotypes. The parental genotypes Line 1 and Line 2 and most of their crosses gave the most desirable values in most earliness traits. The crosses Line 1 × line 2, Line 1× Sonalica, Giza 163 × Gemmeiza 9 and Sakha 61 × Giza 163 gave the lowest mean values of earliness traits in early sowing date. Meanwhile, the crosses Line 1 × Line 2, Line 2 × Sonalica and Line 1 × Line 3 gave the best values toward earliness at normal sowing date. The cross between Line 1 and Line 2 was the most superior one in its earliness traits at the two sowing dates. Genotypes mean squares for all earliness traits were highly significant at the two sowing dates. The highest and desirable values of heterosis percentage relative to the mid parent for days to first node, to booting and days to heading were obtained from cross Giza 163 × Sids 1 at the two sowing dates, for days to anthesis from cross Giza 163 × Sids 1 under early sowing date and from cross Line 1 × Giza 163 at normal sowing one and, for days to maturity from cross Line 1 × Giza 163 at the two sowing dates. The best crosses over better parent for grain filling period was cross Giza 163 × Sids 1 under the two sowing dates, for grain filling rate was crosses Sakha 61× Giza 163 and Line 2 × Line 3 at the two sowing dates, respectively. General and Specific combining ability mean squares were highly significant for all traits under study at early and normal sowing dates. The GCA/SCA ratios were more than unity for all earliness traits at both sowing dates except for grain filling rate under normal sowing date. Based on general combining ability estimates, the best combiners at early and normal sowing dates for days to first node, to booting, to heading, to anthesis and for days to maturity were Line 1 and Line 2; and for grain filling period and grain filling rate were Giza 163 and Gemmeiza 9. Based on the estimates of specific combining ability estimates, the best cross for days to first node, to booting, and days to heading was cross Giza 163 × Sids 1 at both sowing dates, for days to anthesis was Giza 163 × Sids 1 at early sowing date and Sonalika × Giza 163 at normal sowing date; for days to maturity was Line 1× Giza 163 at early sowing date and Sakha 61 × Sonalika at normal sowing date, for grain filling period were Sakha 61× Giza 163 and Sakha 61× Sonalika at both sowing dates, respectively. For grain filling rate, the best crosses were Sakha 61 × Giza 163 and Line 2 × Line 3 under the two sowing dates, respectively.