根域水分调控对不同砧木苹果幼树生长和叶片光合特性的影响

Root-zone water control affects the growth and leaf photosynthetic characteristics of young apple trees grafted onto different rootstocks

以3年生盆栽不同砧木红富士苹果幼树为试材,研究了土壤水分对树体生长和叶片光合特性的影响。结果表明:土壤含水量对苹果新梢生长速率、2次生长的发生和生长时间起到了调控作用。在土壤相对含水量为(75±5)%、(60±5)%处理下,3种砧木苹果幼树新梢均有2次生长,且随着土壤含水量的增多2次生长提早。3种砧木苹果幼树的新梢生长量随着土壤含水量的降低显著降低,其中JM7砧木苹果幼树的降幅最小。不同处理下3种砧木苹果幼树叶绿素含量与对照相比没有下降,而SH40砧木苹果幼树叶绿素含量升幅在春梢停长期与秋梢生长期显著高于其他砧木苹果幼树。随着土壤含水量的降低,3种砧木苹果幼树叶片净光合速率、蒸腾速率、气孔导度均呈下降趋势,但不同砧木苹果幼树对不同水分处理的响应不同。JM7砧木苹果幼树在不同处理下与对照相比净光合速率降幅较小,而蒸腾速率降幅较大,所以其瞬时水分利用效率升幅最大。本试验中,在土壤相对含水量为(60±5)%处理下,树体可以正常生长,提高水分利用效率。

The experiment was carried out with three-year-old pot-cultured Fuji young apple trees grafted onto different dwaft rootstocks. Effects of soil water content on the growth and leaf photosynthetic characteristics were studied. The results showed that new shoots growth and the time of new shoots second growth was attected by soil water content. New shoots of all apple trees acquired the second growth in the test groups of soil relative water content of（75± 5）% and （60±5）%, and higher soil water content resulted in earlier second growth of new shoots. As soil water content decreased, new shoots growth of all the tested trees was signifi- cantly decreased, and the decreasing range of Fuji/ JM7 was found as the smallest among the different trees. Chlorophyll contents of all the tested trees was not decreased, and the in- creasing range of Fuji/ SH40 was significantly higher than the other two trees in the suspending stageof spring and growth stage of autumn. When soil water content decreased, i net photosynthesis rate, transpiration rate, and stomatal conductance were gradually decreased. Test results showed different parameters responses to different soil water content. Compared with CK, the net photosynthesis rate in Fuji/JM7 under different treatments was slightly decreased, its tran- spiration rate was highly decreased, and its instantaneous water use efficiency was greatly im- proved. Test results also demonstrated that （65±5）% was the appropriate soil relative water content according to apple tree growth status and water use efficiency.