EFFECTS OF REGULATED DEFICIT IRRIGATION ON GRAIN YIELD AND QUALITY TRAITS IN WINTER WHEAT

A better understanding of the influence of water deficit on grain yield and quality in wheat is important for agronomists and farmers developing management practices for improved quality. A barrel experiment was conducted in 2011-2012 and 2012-2013 to investigate the effects of water deficit on the relationship between grain yield and quality of winter wheat. The experimental treatments of three growth stages (beginning of spring growth, stem elongation, and grain filling) x three levels of water deficit (60% to 65%, 50% to 55%, and 40% to 45% of field capacity (FC) for light, moderate, and severe deficit, respectively) were laid out in a randomized complete block design with three replicates. A non-deficit control (CK) (75% to 85% FC from sowing to maturity) with three replications was also included. A negative linear correlation between grain protein content (GPC) and soil water content (SWC) was observed at the stem elongation stage in both years. Light or moderate water deficit prior to the stem elongation stage did not significantly reduce grain yield (GY), protein yield (PY), or amino acid yield (AAY) compared with full irrigation. Light water deficit during the grain filling stage did not significantly decrease grain yield and was significantly associated with improved grain quality and water conservation. The results demonstrated that the relationship between GY and GPC changed due to different treatments. Findings suggested that light or moderate water deficit prior to the stem elongation stage, or light water deficit at the grain filling stage, promote high yield and grain quality in winter wheat.