Effects of Foliage Removal and Using Different Nitrogen Rates on Remobilization of Pre-anthesis Assimilates to the Grain in a Dual-purpose (Forage and Grain) Barley

Abstract

In order to study the source limitation and contribution of pre-anthesis assimilates to grain in dual-purpose (forage and grain) barley, a field experiment was carried out in Iran, Ahvaz region. The experimental design was split plot in randomized complete block with three replications. Application rates of nitrogen at four levels (60, 120, 180 and 220 kg.ha^-1 N) were as main plots, while sub plots were three harvesting levels (no cutting crop, cutting at five and 10 cm above ground level). Spikelet removal from one side of spike was done to determine source limitation. Results indicated that foliage removal (FR) from five and 10 cm above ground level reduced grain yield 32% and 15.8%, respectively. Highest grain yield (530 g.m^-2) was obtained by using 120 kg.ha^-1 N treatment. Source limitation was increased with harvesting 28% and 23% in cutting crop from 5 and 10 cm level, respectively. Grain yield was generally reduced with increasing source limitation in dual-purpose barley crop. In cutting treatments, minimum source limitation was obtained with 120 kg.ha^-1 N. The contribution of dry matter translocation pre-anthesis assimilates to grains was reduced by foliage removal treatments, due to reduction in vegetative growth at anthesis stage. Contribution of dry matter remobilization and current photosynthesis to grain yield were increased (11%) and reduced (8.7%) respectively by foliage cutting at 5 cm above ground level.