Combining ability analysis over F1-F5 generations in diallel crosses of bread wheat
SummaryCombining ability studies for grain yield and its primary component traits in diallel crosses involving seven diverse wheat cultivars of bread wheat (Triticum aestivum L.) over generations F1-F5 are reported. The general and specific combining ability variances were significant in all generations for all the traits except specific combining ability variance for number of spikes per plant in the F5. The ratio of general to specific combining ability variances was significant for all the traits except grain yield in all the generations. This indicated an equal role of additive and non-additive gene effects in the inheritance of grain yield, and the predominance of the former for its component traits. The presence of significant specific combining ability variances in even the advanced generations may be the result of an additive x additive type of epistasis or evolutionary divergence among progenies in the same parental array. The relative breeding values of the parental varieties, as indicated by their general combining ability effects, did not vary much over the generations. The cheap and reliable procedure observed for making the choice of parents, selecting hybrids and predicting advanced generation (F5) bulk hybrid performance was the determination of breeding values of the parents on the relative performance of their F2 progeny bulks.
STUDY OF COMBINING ABILITY AND GENETIC PARAMETERS FOR YIELD AND ITS COMPONENTS IN WHEAT
A set of seven wheat varieties from two different ecogeographical origins were studied in a diallel cross to find out the combining ability and the genetic parameters for yield and its components. The general and specific combining ability estimates for spike number per plant, spikelets per spike and seed size indicated predominance of additive gene effects, while for yield the variance for general and specific combining ability were of same order, suggesting importance of additive as well as non-additive effects. Per se performance of the varieties was in close agreement with the general combining ability estimate.The Vr-Wr and Wr-W' graphs showed overdominance for spikes per plant, spikelets per spike, 100-kernel weight and grain yield. In general the predictions regarding the parents made from general and specific combining abilities are in line with gene action indicated by the Vr-Wr and Wr-W' graphs for different characters.Implications of the genetic parameters on breeding approach in wheat have been discussed.
Influence of Diluted Spent Wash of Sugar Industries Application on Yield of and Nutrient Uptake by Sugarcane and Changes in Soil Properties
A pot experiment was conducted to study the effect of irrigation with tube well water (S0) as well as with spent wash diluted for 25 (S25), 50 (S5O) and 100 (S100) times on yield of and nutrient uptake by sugarcane grown on Typic Chromustert. The results revealed that application of spent wash diluted at any level increased the sugarcane yield and nutrient uptake significantly over S0. Less diluted spent wash gave higher yield of biomass than the concentrated one. Though, there was tendency for slight increase in the soil salinity due to use of spent wash, yet the nutrient availability of P, K and S increased considerably. Further, there was indication of betterment in some physical conditions of soil.