金矮生苹果土壤水分合理供给范围研究

对7年生田间和2年生盆栽金矮生苹果(Malus pumila)不同土壤水分(SWC)条件下水分利用效率(WUE)研究表明。SWC约为10％时，WUE最大值在所有处理中最高(230μmolCO₂·g^-1 H2O)；在水分供应充足时，WUE最大值只有160μmolCO₂·g^-1 H2O左右，各SWC水平间差异不显著．WUE随SWC的变化与光照条件有关。

Optimum soil water supply range of Malus pumila

By means of the determination of net photosynthetic rate and transpiration rate of the leaves of seven-year field and two-year spotted Malus pumila(Goldspur) under different soil water contents and illumination and calculation of water use efficiency (WUE), the optimum soil water supply range of Malus pumila was determined. The results showed that: because photosynthetic advantageous radiation (PAR) and soil water content (SWC) decided the value of photosynthetic rate and transpiration rate of Goldspur, thus they influenced the value of WUE. The response of WUE to illumination had relations with soil water. When SWC was 10% (50% of field capacity-FC) or so, the maximum of WUE was the highest value among all the soil water treatment and reached about 230 umolCO2.. g-1 H2O. When the water supply was adequate (SWC>15% ), the maximum was only 160 umolCO2.g-1H2O or so, the difference between each SWC level was not obvious and simulated curve fundamentally overlapped, although WUE decreased slowly after reached the maximum. The variation of WUE with SWC had relations with illumination. WUE was the highest while PAR was in the range of 500~1 000 umol.m-2. s-1). Because the state of soil water decided the values of stomatic resistance (RS) and leaf water potential, RS and also had influence on the changes of WUE.When RS and were respectively 2.0 s. cm-1 and -3.0 MPa, WUE was the highest, but Pn was relatively low, which was not good to the normal growth and fruitage of trees. From the overall consideration of WUE, Pn and Tr, the scopes of RS and were 2 ~6 s.cm-1 and -2.1 ~-1.65 MPa, respectively, which not only guaranteed the normal photosynthesis of Goldspur, but also benefited the increase of WUE. The scope of the corresponding SWC was 11% ~ 15% , which was equal to 55% ~ 75 % of FC and this scope could be used as theoretical index of field water supply for Goldspur.