Water Requirement And Consumption Characteristics And Water Use Efficiency Of Aerobic Rice Under Different Irrigation Treatments

The experiment was carried out in Chang Ping station of China Agriculture University from 2001.3 to 2002.10, to study soil moisture dynamic in aerobic rice field, water requirement and consumption characteristic, root distributing, physiology process, yield formation and water use efficiency under different irrigation treatments. Following primary results were obtained:In the growth period duration, the amount of water requirement of aerobic rice was from 750 to 861 mm, and aerobic rice 502 was from 770 to 773 mm and aerobic rice 297 was rom 750 to 861 mm. The amount and the intensity of water consumption were mostly in the stage between from sowing to emergence and from booting to heading. The maximums of total root length and root weight were in the stage from jooting to heading. The total root length and root weight in 0~60cm soil depressed under water stress, but the root proportion distributed in soil deeper layer enhanced and root length density reduced lowly in deeper soil and the root/shoot ratio increased.The relations between photosynthesis rate and transpiration rate and between photosynthesis rate and stomatal conductance were non-linear. The relation between stomatal conductance and transpiration rate was linear. To sum up, when stomatal conductance was bigger than maximal photosynthesis value, measure could be taken through increasing stoma resistance to restrain from transpiration. It was feasible to not only save water but also improve yield.Comparing to full irrigation wO treatment, the limited irrigation before jointing w2 treatment behaved best in 2001.The amount of irrigation and water consumption were smaller, and root proportion distributed in deeper soil layer enhanced. The yield, seed setting rate, 1000 grains weight and agricultural water use efficiency of the w2 treatment decreased lowest, and output-input ratio and pure benefit per hectare also decreased lowest. But in 2002, the limited irrigation before jointing w3 treatment behaved best.Under gaven 552-562 mm water(irrigation and rainfall), the yield of aerobic rice 502 was only 3.04-3.58 t ha-1 and WUE at yield level was only 0.55~0.64 gkg-1 and the yield of aerobic rice 297 was only 2.55-2.97 t ha-1 and WUE at yield level was only 0.46-0.53 g-kg-1.But if gaven 727-933 mm water(irrigation and rainfall), the yield of aerobic rice 502 could get to 5.34-5.66 t ha-1 and WUE at yield level could get to 0.61-0.73 g kg-1, and the yield of aerobic rice 297 could get to 4.71-5.29 t ha-1 and WUE at yield level could get to 0.57-0.65 g kg-1.The total root length, total root weight, yield, seed setting rate and economic coefficient of aerobic rice 502 were better than aerobic rice 297.The yield structure, daily average water use efficiency and economic benefit of aerobic rice 502 were also better than aerobic rice 297.