Effect of water stress at three growth stages on the yield and water-use efficiency of dwarf wheat

Summary

The responses of dwarf wheat (Iriticum aestivum L.) to three levels of water stress at three growth stages, planting to jointing, jointing to flowering and flowering to maturity was studied under field conditions over two seasons at Hissar, India. At each of these stages, plants were subjected to three levels of water stress viz. −0.5, −1.0 and −1.5 MPa mid-day leaf water potential; during the remaining growth period, the plants were irrigated at 50% available soil moisture (ASM). Thus mild, moderate and severe stress treatments were compared with a no stress control (irrigation at 50% depletion of available soil water). A maximum grain yield of 5.20 tonnes ha⁻¹ was recorded with no water stress treatment. All levels of water stress except −0.5 MPa during flowering to maturity reduced the grain yield significantly compared to the no stress treatment. The greatest effect of water stress on grain yield was observed during the planting to jointing stage. At this stage the highest reduction in grain yield (33.5%) was observed with −1.5 MPa plant water stress. Similar plant water stress during jointing to flowering and flowering to maturity reduced the grain yield by 26.0 and 22.6% respectively. During flowering to maturity, the effect of water stress on straw yield was not well marked. During planting to jointing and jointing to flowering stages, mild, moderate and severe water stress decreased the number of ear-bearing culms, where as number of grains per ear reduced with all water stress levels at all the stages except −0.5 MPa water stress during flowering to maturity. Maximum reduction in 1000-grain weight was observed with all stress levels imposed during flowering to maturity stage. Water-use efficiency was highest with no water stress (13.9 kg/ha mm) and lowest with −1.5 MPa plant water stress (11.2 kg/ha mm) imposed during planting to jointing stage. Results indicate that, the wheat crop should be irrigated at 50% depletion of available soil water (ASW).