EFFECT OF EARLY-STAGE REGULATED DEFICIT IRRIGATION ON STEM LODGING RESISTANCE, LEAF PHOTOSYNTHESIS, ROOT RESPIRATION AND YIELD STABILITY OF WINTER WHEAT UNDER POST-ANTHESIS WATER STRESS CONDITIONS

A field micro-plot experiment was conducted to study the effect of early-stage regulated deficit irrigation (RDI) on the stress tolerance of winter wheat in the late growth stage. Plants were subjected to two RDI treatments: proper water deficits (45-55% field water capacity) were imposed during tillering-the beginning of the spring growth stage (T1) and during the beginning of spring growth to the end of the stem elongation stage (T2). The control plants (CK) were maintained with an adequate water supply until anthesis. The results showed that T1 and T2 shortened the length of the first and second internodes, and increased their weight per unit length, and thereby enhanced stem lodging resistance. Although post-anthesis drought and waterlogging lowered leaf photosynthetic rate and root respiration rate, the two RDI treatments improved significantly compared to the control. The two RDI treatments had no significant effects on grain yield under post-anthesis well-watered conditions but increased grain yield and yield stability of wheat under post-anthesis water stress. In addition, T1 and T2 significantly reduced water consumption and increased water productivity (WP) of wheat compared to the control. In summary, this study shows that appropriate RDI at early growth stages increased grain yield and yield stability through improving population characteristics, root respiration and photosynthesis of plants under post-anthesis water stress conditions. Copyright (C) 2016 John Wiley & Sons, Ltd.