SELECTION FOR BIOMASS YIELD IN WHEAT

Biomass (above ground plant parts) yield may be a useful selection tra it for yield improvement in wheat (Triticum aestivum L.). This study w as conducted to estimate realized heritability of biomass yield and to determine the response to selection for high and low biomass yield in 8 genetically diverse populations of spring wheat under two productio n systems. Selections were made among the F-3 lines. Progenies of the selected lines were evaluated in replicated field tests in the F-4 gen eration under high fertility and low fertility production systems at R ampur, Nepal, in 1991. Fertility level had a significant effect on bio mass yield, grain yield, effective tiller number, number of kernels pe r spike, thousand kernel weight, and harvest index. Selection in the F -3 for high and low biomass yield was effective in identifying F-4 lin es with high and low biomass yield, respectively. Biomass yield differ ences between high and low selection groups in the F-4 generation, exp ressed as percent of the mean of the low selection group and averaged over the eight populations, were 53.9 and 36.5% higher than the mean o f the low selection group under the high and the low fertility product ion systems, respectively. The corresponding figures for grain yield w ere 48.8 and 34.9% under the high and the low production systems, resp ectively. Also, selection for high biomass yield resulted in higher ef fective tiller number, and number of kernels per spike, but lower harv est index. Realized heritability estimates for biomass yield were grea ter at high fertility (range 0.49 to 0.85) than at low fertility (rang e 0.22 to 0.44). Biomass yield showed positive genotypic correlations with grain yield, effective tiller number, and number of kernels per s pike but a negative correlation with harvest index. The results indica ted that selection for high biomass yield should bring about positive improvements in biomass yield, grain yield, effective tiller number, a nd number of kernels per spike. The correlation between F-3 amd F-4 ge nerations suggested that biomass yield in the F-3 generation was a goo d predictor of biomass yield and grain yield in the F-4 generation. Se lection for biomass yield in wheat should be made under the standard p roduction system to obtain a realistic response.