不同水源灌溉对水稻高温热害影响的微气象学分析

Micrometeorological Analysis of the Effects of Different Irrigation Water Sources on the Heat Stress of Rice

高温热害是长江中下游地区水稻常见的农业气象灾害,井水和池塘水灌溉是水稻高温热害过程中常用的农业措施。为研究高温热害下不同灌溉水源对稻田微气象的影响,以两优培九为研究对象,在高温热害期间(2016年8月12-18日)开展田间试验。试验分3个处理,T1:用池塘水每日8:00灌溉,田间水层达10cm后停止,18:00排干,灌溉水温平均30.5℃;T2:用井水每日8:00灌溉,田间水层达10cm后停止,18:00排干,灌溉水温平均18.2℃;CK:试验开始当天用池塘水灌溉至田间水深达10cm后停止,夜晚不排放,当田间水深低于5cm时补充灌溉至10cm,试验期间每日8:00田间平均水温27.2℃。对稻田不同层次的土温和水温、水稻冠层不同层次温湿度、冠层顶部(120cm)叶温、冠层上方太阳辐射等指标进行测定,用Penman-Monteith分层模式计算稻田能量平衡各分量的日变化。结果表明:白天(8:00-18:00),所有处理各层次冠层内气温和地温均为T1>CK>T2,随着冠层高度增加,处理间气温差异逐渐减小;随着土壤深度增加各处理间地温差异逐渐减小。夜间(18:00-次日8:00),各处理间5cm地温差异最大,其次为冠层40cm处。不同灌溉水温改变了各处理的能量平衡分量,水体含热量的变化(Q)表现为T2>CK>T1,土壤热通量(G)、显热通量(H)和潜热通量(LE)均表现为T1>CK>T2。说明较高温度的池塘水灌溉加重了水稻的高温热害,而较低温度的井水灌溉对抵御高温热害有良好效果。

Heat stress is one of the common agrometeorological disasters in the rice production in the middle and lower reaches of the Yangtze River in China.To mitigate the effect of heat stress on rice growth,irrigation with pond or well water was usually adopted,and which is considered to be an effective measure.In this paper,the effect of the irrigation with different water sources was evaluated by a field experiment conducted in Nanjing from August 12 th to 18 th,2016,during which time a heat stress had just occurred.The rice variety Liangyoupeijiu was used in the experiment and three daily irrigation treatments,set as T1,T2 and CK,were implemented.For T1 and CK,pond water was used for the irrigation,and well water was used for T2.For all treatments,the irrigation started from 8:00 and stopped when the height of water layer reached about 10 cm.For T1 and T2,the paddy water was drained out at 18:00;but for CK,the water was kept with a height between 5 and 10 cm.The average temperature was about 30.5℃and 18.2℃for pond and well water respectively.Since CK kept the water in the field,the average temperature of the paddy field water at 8:00 was about 28.2℃.The temperature and humidity within the rice canopy at four different heights(40 cm,80 cm,120 cm and 130 cm),leaf temperature at the canopy top,and solar radiation above the canopy were measured.With the observations,the diurnal variation of each energy balance component in the paddy field was calculated using the Penman-Monteith stratification model.The micrometeorological characteristics of the paddy fields were analyzed.The results showed that from 8:00 to 18:00,the order of canopy temperatures for three treatments were T1>CK>T2.However,the difference of the canopy temperatures among the treatments decreased with the height within the canopy.Similarly,the difference of paddy soil temperatures among the treatments decreased with the depth in the soil.From 18:00 to 8:00,the difference of soil temperature at 5 cm depth was the most obvious among the treatments.The difference of the canopy temperature at 40 cm height within the canopy was the second one.The analysis indicated that the relationship between the changes of the energy balance of paddy fields and the irrigation water was close.The order of the heat storage in water(Q)was T2>CK>T1.And the orders of soil heat flux(G),sensible heat flux(H)and latent heat flux(LE)were T1>CK>T2.These results suggested that irrigation with pond water could aggravate the heat stress on rice,while irrigation with well water is benefit to reduce the effect of heat stress on rice growth.