POPULATION DIFFERENCES AND INHERITANCE FOR SOME PRODUCTION TRAITS IN BREAD WHEAT

Abstract

Diallel analysis is a useful technique to study the inheritance pattern of traits. Eight wheat cultivars and their straight diallel crosses in F2 and F3 populations were studied for various traits at Agricultural University, Peshawar during 2006-2007 and 2007-08. The parent cultivars and their half diallel 28 F2 and F3 populations were planted in randomized complete block design with four replicates. Each entry was planted in four-row plot of five meter length with row to row space of 30 cm. Data for yield and its contributing traits were recorded on randomly selected ten plants in parent cultivars while 30 plants in F2 and F3 populations. Pooled analyses revealed significant differences for all traits in parent cultivars, F2 and F3 populations. Trend in heritability estimates and genetic advance for various traits were inconsistent in F2 versus F3 populations. Diallel analyses of F2 populations depicted significant variation for both additive and non-additive components for all traits except number of tillers in both years and thousand kernel weight during 2006-07. Dominance components b1 and b2 were significant for all traits. However, b2 value was non significant for number of tillers in both years and for spikelets spike-1 and thousand kernel weight only during 2006-07. The b3 component was significant for all traits except number of tillers, spikelets spike-1, biological yield and grain yield during 2006-07, and plant height, spike length and thousand kernel weight during 2007-08. Additive dominance model was partially adequate for all traits except number of tillers, thousand kernel weight and harvest index during 2006-07. The values of genetic components and Vr/Wr graph of F2 material suggested preponderance of non-additive gene action for all traits in both years except grain spike-1 during 2007-08. Average degree of dominance being greater than unity for all traits also suggested over dominance for controlling these traits. Significant GCA and SCA differences reflected important role of additive and non-additive gene actions in both years, however, higher magnitude of SCA variances indicated preponderance of non-additive gene action for all traits. None of the individual populations showed superiority for all traits, however, Iqbal-2000 x Ghaznavi-98 performed better for most of the traits in both generations. Based on mean perforamance,Tatara-96 and Ghaznavi-98 with early flowering and medium stature appeared better cultivars for yield and related traits, while Khattakwal and Margalla-99 being late maturing and tallest exhibited maximum mean values for tillers number, spike length and biological yield appeared as poorest. Similarly, Iqbal-2000 x Ghaznavi-98, Tatara-96 x Iqbal-2000, Wafaq-2001 x Iqbal-2000, Takbeer x Ghaznavi- 98, Wafaq-2001 x Ghaznavi-98 and Tatara-96 x Ghaznavi-98 were better performing populations in both generations.