陕西渭北旱塬土壤—植物—大气连续体中水分运转规律的研究──Ⅴ．田间冬小麦土壤—叶片途径水运转阻力研究

STUDIES ON WATER TRANSPORTS IN THE SOIL-PLANT-ATMOSPHERE CONTINUUM ON WEIBEI RAINFED HIGHLAND SHAANXI PROVINCE──Ⅴ.STUDIES ON WATER TRANSPORT RESISTANCES IN SOIL-LEAF PATHWAY IN FIELD WINTER WHEAT

采用Ｍｉｓｈｉｏ和Ｙｏｋｏｉ（１９９１）的方法，在水分运转阻力短期内（如几个小时）恒定不变的假设下，研究了田间冬小麦土壤—叶片途径水分运转阻力．结果表明，一天中，当气孔没有“午休”现象或“午休”现象不明显时，冬小麦土壤—叶片途径水分运转阻力在白天保持恒定，到夜晚则明显增大；当气孔“午休”现象较明显时，冬小麦土壤—叶片途径水分运转阻力在气孔“午休”期间和夜晚明显增大，其余时间基本保持恒定．夜间和气孔“午休”期间阻力增大的原因不确定．土壤干旱条件下冬小麦土壤—叶片途径水运转阻力显著大于土壤湿润条件下，表明水运转阻力与植物抗旱性有关．土壤干旱条件下施肥处理冬小麦土壤—叶片途径水运转阻力显著大于不施肥处理，而土壤湿润条件下显著小于不施肥处理，表明施肥对植物具有调节作用，使之更好地适应干旱环境．

Based on the assumption that water transport resistance is essentially constant for relatively short periods(e.g.within few hours),the present study was carried out to research into the water transport resistance in soil-leaf pathway in field winter wheat(Triticum aestivum cv.Shaanhe No.6).Resistance showed little variation with change in leaf water potential and transpiration rate by day but particularly high in the night in all cases,suggesting that resistance increased remarkably when transpiration rate was low,and in the periods of stomatal midday depression. Both reasons for resistance increase in the evening and during stomatal midday depression are uncertain.Resistance under soil drought was significantly higher than that under soil moist,showing that there is a close relationship between water transport resistance and plant acclimation to drought.Resistal ces of fertilization treatments under drought were significantly higher than the control,but significantly lower than the control under soil moist, indicating that fertilization has the effect of regulation to plant,making it more adaptable to drought environment.