The role of water deficit stress and water use efficiency on bread wheat cultivars.

Abstract

Objective: To study the effects of drought stress on yield and water use efficiency of three wheat cultivars under field condition. Methodology and results: Two similar and concurrent experiments were carried out between 2007-2008 in the Dryland Agriculture Research sub-Institute Sararood and the Mahidasht Agricultural Research Center. The experiments were conducted based on split plot in a randomized complete block design with three replications. The main plots included drought stress treatments at 4 levels: I1-drought stress at the start of stem elongation stage ( 31 Zadoks) through the ripening stage with irrigation after 80% depletion of soil moisture; I2drought stress at the start of boot stage ( 43 Zadoks ) through the ripening stage with irrigation after 80% depletion of soil moisture; I3drought stress at the start of grain filling stage ( 70 Zadoks ) through the ripening with irrigation after 80% depletion of soil moisture; and I4full irrigation ( irrigation during growth period after 40% depletion of soil moisture). Subplots included cultivars treatments at 3 levels; Chamran (C1 ), Marvdasht (C2) and Shahriar (C3). Results showed that yield, harvest index and water use efficiency were affected by drought stress (I1 , I2 and I3 ), as plants in full irrigation treatment (I4 ) produced the highest grain and biological yields, harvest index and water use efficiency. Water use efficiency varied from 0.66 to 1.34 kg.m-3 between irrigation regimes. Variation of grain yield and biological yield versus utilized water within 2 regions, in the form of linear regression, showed high correlation (R2=0.71, R2=0.82) between them, respectively, and that there was a correlation relationship between yield and water use efficiency. Conclusion and application: The results of the present study showed that Sararood region wheat has higher economical yield, biological yield, and WUE than those of Mahidasht region. Despite the lower WUE in Mahidasht , its total water utilized amount was more than that of Sararood`s . Chamran cultivar (C1) had higher yield stability than the others and its yield reduction under stress conditions was lower than others.