不同供水条件下冬小麦冠气温差、叶片水势和水分亏缺指数的变化及其相互关系

Variation and Interrelationship of Winter Wheat Canopy-air Temperature Difference, Leaf Water Potential and Crop Water Stress Index under Different Water Supply Conditions

为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0^-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。

The field experiments of winter wheat canopy temperature （Tc） under different soil moisture conditions were performed for many years to set up an optimal irrigation schedule and provide theoretical basis to the high-efficient irrigation system based on crop＇s own index. The effects of comprehensive environmental factors on crop canopy-air temperature difference （△T） were anlysised in detail and simulated in different soil water status. Soil moisture condition was used as leading factor in the experiment, crop＇s own factors [ Leaf water potential （LWP）, yield ,etc.] and atmosphere, wind speed, radiation, ground radiation, etc. were also considered. It was shown that difference of canopy temperature was significant for different water treatments in this study, the canopy-air temperature difference was remarkable extremely. The difference of crop water stress index （CWSI） was obvious during different irrigation treatments.However, response lag to crop water stress and deviation appeared easily influenced it＇s to use. △T interrelated with LWP distinctly, correspondingly, CWSI negatively interrelated with leaf water potential, LWP= -1.8 MPa and CWSI= 0.40 could be critical in indicating water stress of winter wheat. To achieve water-saving purpose and get winter wheat optimum output at the same time, value of △T must maintain at 0～4℃ and soil relative water content was 58.7% as the lowest value of water saving irrigation.