早实核桃水分指标的研究

A STUDY ON THE WATER INDEXES OF EARLYFRUITING WALNUT

核桃是重要的经济林树种,早实核桃品种具有很高的栽培价值。我国的核桃产区多位于干旱半干旱地区,春季和初夏干旱少雨,水分不足严重地影响其产量、品质和树体生长,成为制约其生产的重要因素。核桃水分指标的研究尚未见报道,本试验通过对几个水分指标的研究,来确定早实核桃的临界水势及适宜的树体水分指标,为合理灌溉提供依据。一、材料及方法研究采用盆栽二年生早实核桃实生小树。盆的体积约15L。早春选择生长较为一致的小树在室外盆栽培养,基质为混合均匀的棕色壤土,田间持水量为21％。

Two years old early-fruiting walnut seedling were water stress in early July. As the water stress increased, net photosynthesis rate of the leaves decreased from the maximum state slowly first than, rapidly later on, and ultimately completely inhibited. The relations of net photosynthesis and leaf water potential soil water content, leaf water content, stomatal diffusion resistance, and the angle between the first couple leaflets at the top of compound lesf were studied and discussed in this paper. It was shown that the angle and the leaf water potential were the better indexes to indicate the water state of trees than soil water contant. When the angle was more than 90° and the leaf water potential was more than- 1.20MPa, the net photosynthesis rate of leaves could be maintained at higher level. Whereas leaf water content and stomatal diffusion resistance could not be used as the water indexes for early-fruiting walnut. Critical water potential of early-fruiting walnut for stomatal closure was-1.35MPa.