Abstract
The present study was aimed at identifying stable genotypes for grain yield and protein content along with the growth pattern characterization and genetic nature in relation to yield contributing characters. Fifteen genotypes were studied for estimation of stability in sixteen environments. The genetic difference in yield performance was sufficient among the genotypes and simultaneously, environmental difference in yield was observed. But in case of protein content, the genotypic as well as environmental difference was less pronounced.
Out of fifteen, six genotypes 2, 7, 8, 10, 11 and 12 were identified stable for grain yield and four genotypes 7, 8, 11 and 12 for protein content. In estimation of stability, the use of parameters b, S²d and R² including x in combined form based on rank order system was found more efficient than using them individually. Furthermore, a new method was developed where position point (PP) of genotypes was used for identifying stable ones and the parameters b, S²d and R² were were not used. In this case, estimation of percentage of stability and yield potential of genotypes was also possible and accordingly, the genotypes were grouped as high stability plus high yield, high stability plus average yield, average stability plus high yield, average stability plus average yield and so on. In grading the environments for growing wheat in Bangladesh, Dinajpur was the best region and Hathazari was the least favorable one. Ishurdi and Joydebpur were, however, intermediate in their importance. On the other hand, optimum planting was more favorable in comparison to late planting.
In finding out the effect of component characters on yield of stable genotypes, it was observed that the characters had positive effect on yield. But number of spikelets per spike and 1000 grain weight showed signifi- cant positive effect while number of spikes per m2 and number of spikelets per spike showed direct influence on yield. In most of the cases, genotypic correlation coef- ficients were higher than those of phenotypic and envi- ronmental ones.
In growth pattern characterization, the stable geno- types possessed higher amount of dry matter content which, in turn, was more in spikes followed by stems and leaves. However, the total dry matter as well as spike dry matter was significantly and positively correlated with grain yield.
While knowing genetic nature, the stable genotypes were identified superior to others in their combining abilities and were proved to be ideal general combiners for particular yield components.