| The field experiment was conducted from March to July in 2008 to study effects of conbination of agronomic measures on water saving at Wuwei Central Experimental Station in Gansu province. The experiment have two tillage treatments with plastic mulching and straw mulching at three irrigation levels. The purpose of experiment was to study impacts of deficit irrigation under different agronomic management on soil water content, soil temperature, the growth of spring wheat, grain yield and water use efficentcy(WUE) at different growth stages.The main results are as follows:1. During the whole growing period, the soil water content increased with soil depth in 10~80cm, decreased in 80~100cm. However, there were no significant differences in soil water content in 10~100cm between plastic film mulching and straw mulching.2. The overall trend of daily water consumption increased first and then decreased in whole periods. The daily water consumption was highest (7.43 mm·d-1) at heading and blooming, decreased to 3.79 mm·d-1 at maturing. The comsumption coefficiencies were higher at jointing (20.99%), heading (26.42%) and bloming and maturing (31.96%), but the lowest (3.49%) at tillering period.3. Water use efficency (WUE) of treatments (T1 and T4) under the irrigation level B1 was highest, but did not increase as water consumption inceresed.4. The overall trend of soil temperature showed that temperature with plastic film mulching was higher than that with strawing mulching with higher temperature at 0~10 cm, but lower at 20~25 cm. There was significant difference among treatments at certain time.5. The growth stages of spring wheat with plastic film mulching occurred 7~10 days earlier than those with straw mulching which lead to higher leaf area per plant with plastic film mulching and lower with straw mulching at early growing stage. Leaf area per plant under sufficient irrigation was higher than that under deficit irrigation. LAI showed a single-peak curve for all treatments during the growth period with the highest LAI at periods of heading and blooming.6. Dry matter accumulation per plant showed a"S"curve during the whole growth period. Dry matter accumulation per plant was higher under sufficient irrigation than that under deficit irrigation. Effect of different treatments on dry matter accumulation per plant was greater at early period than that of late period. Rate of dry matter accumulation showed a single-peak curve during the whole growth period.7. Agronomic management had no obvious effects on the plant height, spike length, mumer of spikelet, weight per plant, spike weight, number of grain per spike and the thousand-grain weight (P>0.05), but had significantly effect on the grain weight per spike (P<0.05). Irrigation level had significant effects on the plant height, weight per plant, spike weight, number of grain per spike, grain weight per spike and thousand-grain weight (P<0.05) and highly significant effects on the number of invalid spike (P<0.01), but had no obvious effects on the numer of spikelet and spike length (P>0.05). There was no significant interactions between agronomic mangement and irrigation level on yield formation of spring wheat (P>0.05).8. Agronomic mangement had no significant effect on economic production (P>0.05) and had highly significant effects on biomass yield and harvest index of spring wheat (P<0.01). Irrigation level had significant effect on the grain production, biomass yield and harvest index (P<0.01).9. Jensen model was used to establish water production function of spring wheat. The sensitive index was relatively small at early growth period, increased at middle growth period and decreased in later growth period. The sensitive index of spring wheat were 0.0168, 0.1770, 0.4207, 0.2724, 0.1374 for plastic film mulching and 0.0281,0.1579,0.2437,0.3652,0.1822 for straw mulching at the growth period of sowing~tillering, tillering~booting, booting ~ head- ing and blooming, heading and blooming~maturing, respectively.10. Treatment T1 had the highest yield and net income was 5648.48 yuan·hm-2 while T4 was at the second place (5096.39 yuan·hm-2). T4 was the best treatment under irrigation level B1 with straw mulching as plastic mulching involved in great labor intensity and risk of palstic pollution given the shortage of water resource at Wuwei. Therefore, Treatment T4, having water saving and drought resistance, is recommended to be adopted in spring wheat production.
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