北方稻田蒸散需水分析及其作物系数确定

Analysis of paddy field evapotranspiration in North China and calculation of crop coefficient.

利用PenmanMonteith方程估算了中国北方下辽河平原地区52年(1951～2002)的潜在蒸散量,分析了潜在蒸散的年际动态变化规律;在中国科学院沈阳生态实验站的水田实验地上,利用非称重式蒸渗仪对充分供水条件下同一水稻品种稻田蒸散量进行了测定,在此基础上确定了水稻作物系数.结果表明,在北方下辽河平原地区稻田蒸散量变化在581～695mm之间,年际变率为24%.无论是湿润年还是干旱年,由于受降雨量及其时间分配不均的影响,在该地区水稻生产中都需要有灌溉水补充.整个生育期水稻作物系数多年(1993～2002)平均值为132,水稻生育期内作物系数基本符合二次曲线趋势变化.

The potential evapotranspiration(ET_0)values from 1951 to 2002 for the lower reaches of Liaohe Plain,North China,were estimated by Penman-Monteith equation,and the annual change in ET_0 was analyzed.By using non-weighting lysimeters at Shenyang Experimental Station of Ecology(CAS)in North China,the daily evapotranspiration of flooded rice(Oryza sativa L.)at the interval of 10～11 days was determined for eight seasons from 1993～2002(except for 1997 and 1999).The results showed that the total evapotranspiration ranged from 581mm to 695 mm during 1993 and 2002,averaged 634 mm.Both in dry and wet seasons,supplemental irrigation was essential in this region for the uneven distribution of rainfall and time.The average crop coefficient(Kc)for eight years from 1993 to 2002 during the whole growth period was 1.32,with a second-degree polynomial change for the values of Kc during different rice growth stages.