摘要：A field experiment was conducted during 2016-2017 to investigate the effect of
irrigation scheduling on three barley cultivars (viz Nosrat, Roudasht and Behrokh)
under water deficit stress conditions. Irrigation treatment was applied based on the
maximum allowable depletion of available soil water. Treatment levels comprised of
irrigation scheduled at: (I1) 30%; (I2) 60%; and (I3) 90% depletion of available soil
water which was applied after flowering stage. Studied traits included: plant height,
shoot fresh weight, shoot dry weight, the number of spikes per plant, the number of
grains per spike, 1000-grain weight, awn length, harvest index, biological yield,
grain yield, and total protein content of grain. Results showed that all traits were
significantly reduced with an increase in the severity of stress due to a reduction in
the availability of water. However, no significant reduction was observed for cultivar
Nosrat regarding grain yield, biological yield and the number of spikes per plant
between I2 and I3 treatment levels. Estimation of production functions with respect
to yield contributing traits revealed that, at a severe drought stress, the order of the
importance of yield-contributing traits was as: harvest index>biomass>spikes per
plant>grains per spike. Based on the results, to achieve the highest grain yield and
grain total protein content, irrigation should be scheduled at a maximum allowable
depletion equal to 30% of available soil water. Nevertheless, an economic
production can be achieved with a delayed irrigation.
关键词：drought stress; grain yield; production function; standardized regression
