Effects of irrigation amount and stage on yield and water consumption of different winter wheat cultivars

Winter wheat (Triticum aestivum L.) is the main cereal crop grown in the arid and semi-arid regions of the world. Average yields of winter wheat in many countries have increased by 40% over the past five decades due to the development of new cultivars, improvements of crop management practices and changes of favorable climate. However, water shortage is becoming an important factor limiting sustainable winter wheat production in many parts of the world. The greatest challenge for the winter wheat producers is to produce more wheat grain from limited water, and an available way to face the challenge is to improve winter wheat water productivity. Winter wheat water productivity had been significantly improved in the last 25 years, but there is still a big room for improving further. Selecting cultivars with more efficient water use is a key means to reduce water consumption in winter wheat production in the water-scarce regions. A field experiment was carried out during 2010 to 2011 and 2011 to 2012 growing seasons of winter wheat to clarify the variations in water consumption, grain yield, and water use efficiency (WUE), and their responses to water stress during the process of cultivar replacement in past decades. Seven cultivars of winter wheat released from 1950s to the current, in which each cultivar was once widely planted in north central Henan province during a certain decade, were taken as experimental materials. At the mean time, three irrigation regimes were designed including no irrigation after turning green (W0), irrigation applied only once at jointing (W1), and irrigation applied at jointing, and at filling, respectively (W2), to investigate dynamics of water consumption characteristics, yield components, harvest index, and WUE of winter wheat. Results showed that precipitation and timing of irrigation significantly impacted total water consumption and soil water extraction of winter wheat while different planting decades had insignificant effect on them. 1000-kernel weight during 1990s to the current kept more than 41 g, significantly higher than that during the earlier planting decades. During the 2010 to 2011 and 2011 to 2012 growing seasons, grain yields of winter wheat were increased by 396 and 362 kg/hm2, or 58.4% and 41.8% higher than the average yield across 1950s to the present, respectively; similarly, harvest indices were increased by 37.0% and 18.0%, an increase of 0.2 and 0.1 from the previous average indices; WUE was increased by 55.3% and 40.8%, an increase of 0.11 and 0.10 kg/m3, respectively. Improvement of grain yield is mainly attributable to the improved source to sink relationship, boosted 1000-kernel weight, and increased harvest index. Grain yield and WUE are significantly influenced by cultivar × soil water interaction, and can be significantly improved by supplemental irrigation applied at jointing and at filling stages of winter wheat.