ANALYSIS OF PHYTOMASS IN 36 IRANIAN WINTER WHEAT (Triticum aestivum L. em. Thell.) GENOTYPES

Wheat (Triticum aestivurn L. em. Thell.) grain yield shows high genotypeenvironment interaction, and thus a slow response to direct selection for yield. Selection, criteria other than grain yield (i.e., harvest index) are being sought by wheat breeders. Further improvement in harvest index appears difficult and future increases in grain yield may have to come through increases in phytomass production. A study was conducted to investigate the association between harvest index and phytomass of single plants and plot grain yield. A considerable diversity was found among 36 cultivars of Iranian wheat genotypes for these traits. More variation was found in phytomass than harvest index. However, harvest index was found to be the most stable trait giving the highest correlation with plot grain yield. It was concluded that harvest index of single plants is a suitable predictor for yielding ability where the available seed for yield study is limited, and is a potential criterion in selection indirectly for increased grain yield in Iranian wheat genotypes.