基于冠层温度的水稻关键生育期缺水诊断

以船行灌区水稻为试验作物,在2014年7-10月水稻生长发育的分蘖期、拔节孕穗期、开花结实期等3个关键期进行水稻需水试验,研究水稻冠层温度、大气温度与土壤含水量的关系,提出作物缺水诊断方法.研究结果表明:冠层温度晴天变化趋势随气温变化差异较大,阴雨天与大气温度差异不大,这与晴天水稻蒸发蒸腾强度高而阴雨天蒸发蒸腾强度低有关;抽穗开花期冠气温差在午间呈现正值,其他时间大多为负值,而成熟期冠气温差基本为正值且午间最大;通过水稻拔节孕穗期和开花结实期间冠气温差和对应时段内土壤适宜含水率上下限的对比,确定直播和插秧稻在拔节孕穗期的冠气温差上限达到1.5 ℃时,在开花结实期冠气温差上限分别超过2.4 ℃和2.5 ℃时,土壤水分已达胁迫水平,应对水稻进行灌溉.通过监测冠层温度,可以便捷地获取水稻缺水状况.

Diagnosis of water shortage in key growth period of rice based on canopy temperature

Canopy temperature is an important index to analyze crop water demand. Taking rice in Chuanhang Irrigation Area as the experimental crop, its water requirement was tested at three key stages of rice growth: tillering stage, jointing and booting stage, flowering and fruiting stage from July to October in 2014. This experiment not only studied the relationship between rice canopy temperature, air temperature and soil moisture content but also proposed the diagnosis method of crop water shor-tage. The results showed that the variation trend of canopy temperature in sunny days varied greatly with air temperature, while in rainy days varied little difference. It related to the high evapotranspiration intensity of rice in sunny days and the low evapotranspiration intensity in rainy days. The canopy-air temperature difference in the heading and flowering stage was positive in midday, but negative at other times, while that in the mature stage was positive and maximum at noon. Compared with the canopy-air temperature differences with the appropriate moisture content limits at different stages of rice growing periods, when the canopy-air temperature differences of direct seeding rice and transplanting seeding rice were both greater than 1.5 ℃ in the jointing and booting stage, and they were greater than 2.4 ℃ and 2.5 ℃, respectively, in the flowering and fruiting period, the soil water content reached the crop growing stress level, and the rice should be irrigated. By monitoring canopy temperature, the rice water shortage could be conveniently obtained.