不同水分状况下红壤水稻的小量平衡和生产能力

在我国中亚热带典型红壤区通过水稻测坑试验，测定了农田水量平衡各分项。结果表明，低、中、高水分条件下早稻的蒸散需水量为３６８．６～４１５．４ｍｍ，日均蒸散量为４．２９～４．８３ｍｍ／ｄ。５月～７月的降水总量可以满足早稻的蒸散和渗漏需要，并有多余的水分需排出。但由于降雨间隔不匀，仍需少量灌水来补充调节。晚稻低、中、高３种水分状况下蒸散量为３３４．９～３８４．２ｍｍ，略低于早稻，但日均蒸散量高于早稻。即

The Water Balance and Productivity of Rice under Different Soil Water Conditions in Red Soil Area

The items of water balance of rice were obtained in typical red soil area of mid subtropics by experiments in testing pits. Results showed that the evapotranspiration of first crop rice ranged from 368.6 mm to 415.4 mm under different soil water conditions, and the daily evapotranspiration ranged from 4.29 mm/d to 4.83 mm/d. The total precipitation from May to July was sufficient for first crop rice to meet the evapotranspiration and leakage. And there was excessive water that must be drained. But the precipitations was not evenly distributed and some supplementary water was needed for irrigation. The evapotranspiration of second crop rice ranged from 334.9 mm to 384.2 mm under high, moderate and low soil water conditions. The total evapotranspiration of second crop rice was slightly lower than that of first crop rice, but daily evapotranspiration was higher. Irrigation was needed to meet the water demands of second crop rice even in the high precipitation year. The grain yields in water maintaining treatment were lower than that of in moist treatment in the high precipitation year. The panicles per plot and 1000 grain weight decreased, and the spikelets per panicles and filled percentage increased in the lower water treatment in first crop rice. The filled percentage and 1000 grain weight decreased, and the panicles per plot increased. The soil water conditions had the highest effects on the spikelets per panicles. Soil water also affected the photosynthetic productivities of rice leaves, but no consistent patterns were found between first crop rice and second crop rice in the experiments.