Contributions to Grain Yield from Pre-anthesis Assimilation in Tall and Dwarf Barley Phenotypes in Two Contrasting Seasons

Abstract

Twenty-four barley genotypes were produced from crosses between two sets of parents each having a different, non-allelic dwarfing gene. Four genotypes were phenotypically tall, twelve were single dwarf and eight were double dwarf. By a combination of carbon-14 labelling and growth measurement the contribution to grain dry matter from assimilation before anthesis was estimated for each genotype in two years, 1976 and 1977. Pre-anthesis assimilation was estimated to have contributed 44 per cent of grain dry matter in 1976, a very dry, hot year, but only 11 per cent in 1977, a wetter, cooler year. These percentages were equivalent to about 133 and 74 g m⁻² in 1976 and 1977. It is shown that some previous estimates of the contribution from pre-anthesis assimilation are too low for crops of barley grown in the field in dry years, while in wet years, the contribution is unlikely to be less than 10 per cent. In neither year did the genotypes differ in the extent to which pre-anthesis assimilation contributed to grain filling. In both years, grain yields of the tall genotypes were 8–9 per cent greater than those of the double dwarf ones, and stem weights at maturity 30 per cent greater.