Abdus Salam Khan

Study of correlation among yield related traits and path coefficient analysis in rice (Oryza sativa L.)

In order to determine the associations among yield components and their direct and indirect influence on grain yield of rice, an experiment was conducted. For this purpose, 30 genotypes collected from different sources were tested in a randomized complete block design. The phenotypic correlations among the yield traits and their path coefficient were estimated. Grain yield was significantly correlated with its component characters; number of productive tillers per plant, number of grains per panicle and flag leaf area. Path analysis revealed that days to maturity had the highest direct effect (0.751) on grain yield per plant. In addition, the yield components had positive direct effect on grain yield except the days to heading (-0.834). The order of yield components was the number of productive tillers per plant, flag leaf area and 1000 grain weight. The improvement in grain yield will be efficient if the selection is based on biological yield components, number of productive tillers per plant and flag leaf area. These traits may also be utilized in pure line selection. Keywords : Rice ( Oryza sativa ), path coefficient, phenotypic correlation, yield components

Breeding potential of the basmati rice germplasm under water stress condition

Eight parents were selected on the basis of phenotypic and genotypic screening for the development of F 1 . All the possible combinations were made between the parents excluding reciprocals in diallel mating design. Data were analyzed by using Hayman graphical approach and Griffing’s approach to study the genetics of the parents and their F 1 hybrids. Based on the genetic component analysis, both additive and non-additive components appeared which is important in the inheritance of most of the traits. Both additive and dominance type of gene action were found important in inheritance for different traits under study. Most of the traits showed constant gene action in both environments, but the gene action of some traits was affected by the environment. Morphological traits like plant height, productive tillers per plant and 1000 seed weight showed over dominance type of gene action in both environments (control and drought environments), while seeds per panicle and seed length width ratio showed this type of gene action only in drought conditions. The seeds per panicle and length width ratio showed additive type of gene action with partial dominance only in normal irrigation conditions. From Griffing analysis, genotypes CB-17, CB-32 and Basmati-198 were found to be good general combiners for productive tillers per plant, primary branches per panicle and yield per plant, especially under water stress condition. Also, maximum specific combining ability was found in Basmati-198 × CB-17 for productive tillers per plant, Basmati-198 × CB-42 for primary branches per panicle and CB-32 × CB-14 for yield per plant. Key words: Oryza sativa L., gene action, combining ability, stress, yield traits.

Patterns of trait associations in various wheat populations under different growth environments

Five wheat populations were investigated for two years to explore the pattern of trait associations and their contribution to grain yield. The correlation pattern between two traits and their association with grain yield was similar in CIMMYT and Pakistani germplasm. Indian germplasm had different pattern of trait association from those of CIMMYT and Pakistani germplasm. The number of kernels per plant, number of spikes per plant, spike length and spike dry weight were the major yield contributing traits in CIMMYT, Pakistani and ICARDA genotypes. In Indian and miscellaneous genotypes, the number of kernels per plant and number of spikes per plant were the only traits with a positive effect on grain yield. Furthermore, three traits, the number of kernels per plant, the number of spikes per plant and the spike dry weight appeared to have positive effect on grain yield and other major yield traits. Spike density had a negative effect on grain yield in CIMMYT germplasm in dry season. Chlorophyll contents showed no correlation with grain yield in all populations.