Yield, Grain Weight and Height Relationships in Two Random Samples of Early Semi-Dwarf Genotypes of Spring Wheat (Triticum aestivum L.)

The objective of this work is to study the association between the genotypic differences in mean grain weight and grain yield, the relationship of yield and grain weight with culm length, and the differences between the effects of the Rht1 and Rht2 dwarfing alleles on these characters. Yield, grain weight, grains m^-2 and culm length were evaluated in two random samples of 19 semi-dwarf early lines, selected in F₅ and tested in F₂, from two different crosses between cultivars differing in the Rht allele controlling their semi-dwarf ness. The lines of each cross were tested in 4-replicated field trials at two different sites. Phenotypic, genotypic, partial and multiple correlations as well as hertability estimates were computed. In each cross the lines differed significantly in their mean values of all the characters tested. In both crosses there was no apparent association between grain weight and grain yield. It therefore seems that in wheat of the type investigated in this study, grain yield and grain weight are independent controlled and that high grain yield is not restricted to any particular range of mean grain weight. A rather high positive correlation between culm length and grain weight was found in one cross but not in the other indicating the dependence of this relationship on the genetic background. In both crosses no significant differences were found between the performance of the lines carrying the Rht1 dwarfing allele and those carrying the Rht2 allele.