The Effect of Late-terminal Drought Stress on Yield Components of Four Barley Cultivars

Barley (Hordeum vulgare L.) is an important winter cereal crop grown in the semiarid Mediterranean, where late-terminal drought stress during grain filling has recently become more common. The objectives of this study were to investigate the growth performance and grain yield of four barley cultivars under late-terminal drought stress under both glasshouse and field conditions. At grain filling, four barley cultivars (Rum, ACSAD176, Athroh and Yarmouk) were exposed to three watering treatments: (1) well-watered [soil maintained at 75 % field capacity (FC)], (2) mild drought stress at 50 % FC, (3) severe drought stress at 25 % FC in the glasshouse experiment and (1) well-watered (irrigated once a week), (2) mild drought (irrigated once every 2 weeks), (3) severe drought (non-irrigated; rainfed) in the field. As drought stress severity increased, gross photosynthetic rate, water potential, plant height, grain filling duration, spike number per plant, grain number per spike, 1000-grain weight, straw yield, grain yield and harvest index decreased. In the glasshouse experiment, the six-row barley cultivars (Rum, ACSAD176, and Athroh) had higher grain yield than the two-row barley cultivar (Yarmouk), but the difference was not significant among the six-row cultivars under all treatments. In the field experiment, Rum had the highest grain yield among all cultivars under the mild drought stress treatment. The two-row cultivar (Yarmouk) had the lowest grain yield. In general, the traditional cultivar Rum had either similar or higher grain yield than the other three cultivars under all treatments. However, the yield response to drought differed between the cultivars. Those, Rum and ACSAD176, that were capable of maintaining a higher proportion of their spikes and grains per spike during drought also maintained a higher proportion of their yield compared with those in well-watered treatment. In conclusion, cultivar differences in grain yield were related to spike number per plant and grain number per spike, but not days to heading or grain filling duration.