Studies On The Irrigation Model Of Aerobic Rice Under Beijing Climate Background

The experiment was carried out in Changping Experimental Station of China Agricultural University from 2001 to 2004. According to field experiment, crop water requirement of aerobic rice during every growth stage was obtained by soil water budget model, reference crop evapotranspiration (RCE) during the growth season was calculated with meteorological data based on revisional Penman formula, and finally the crop coefficient was determined. Base on climate data of Beijing area, the precipitation characteristics during the growth season of aerobic rice were analysed and three different precipitation year styles (PYS) were divided by means of Pearson-Hi distributing method according to rainfall guarantee rates. According to the coupling degree between rainfall and water requirement of aerobic rice under the condition of three PYS, the amount of supplementary irrigation were calculated. Considering full irrigation treatment as control, the results of other deficit irrigation treatments in agronomic, photosynthesis physiology, yield, yield component and water use efficiency (WUE) were compared to ascertain the optimal water-saving irrigation model. Following results were obtained:In Beijing area, the crop water requirement of aerobic rice was 650⁶90mm mainly in two periods, Emergence^Jointing stage and Heading Maturity stage. RCE during the growth season of aerobic rice in Beijing area was 560mm. Two peak periods were Sowing-Emergence and Heading-Maturity stages. The daily average value of RCE was about 3.8mm·d^-1. The crop coefficient during the whole growth season was about 1.06. The staged crop coefficient showed bimodal curve.Two peak values appeared were found at Booting^Heading and Heading-Maturity stages.In growth season of aerobic rice, the mean precipitation was 500.4mm in Beijing. The precipitation absolute value of interannual change was 124.7mm. The relative change rate was 24.9%. The staged precipitation change rate was much more than that in whole growth season. Three PYS were described as humid, middle and dry year style. The standards were more than 640mm, about 500 mm and less than 335mm, respectively. The coupling degrees were 0.75, 0.63 and 0.41, respectively. The amount of supplementary irrigation was 166.5 mm, 246.1mm and 395.1 mm, respectively.Full irrigation treatment W1 always obtained the most values in agronomic, photosynthesis rates, transpiration rates and yield as compared with other treatments. Compared with W1, the yield of W2 reduced the least. The yield were 4.71⁵.91t·ha^-1 and 4.34⁵.54 t·ha^-1 for W1 and W2, respectively. But water use efficiency (WUE) of W2 was higher than W1, and W1 was 0.8³.4g·kg^-1 W2 was 1.1⁴.0 g·kg^-1. Therefore, W2 treatment showed the optimal water-saving irrigation model based on steady yield and higher WUE in Beijing area.