外源甜菜碱对水分胁迫下桃树生理响应的影响

以4年生盆栽“庆丰”桃树为试材,研究了水分胁迫下桃树叶片中甜菜碱含量的变化规律及叶面喷施甜菜碱对水分胁迫下桃树生理响应的影响.结果表明：正常供水情况下,桃树叶片中甜菜碱含量为75.9～80.5 μg·g^-1FM , 随着水分胁迫程度的加深,甜菜碱含量逐渐增加,停水第16 天时达278.9 μg·g^-1FM ；正常供水时桃叶片细胞质膜透性为8.06%～8.61%,水分胁迫下增至28.62%,叶面喷施100和500 mg·L^-1甜菜碱16d后分别为26.25%和21.79%；过氧化氢(H₂O₂)含量由正常情况下的27.2～32.5 μmol·g^-1FM 增至胁迫后的76.4 μmol·g^-1FM,叶面喷施100和500 mg·L^-1甜菜碱后分别为73.2和68.5 μmol·g^-1 FM；水分胁迫下,抗坏血酸过氧化物酶(AsA-POD)活性峰值为0.435 mg·g^-1 FM,甜菜碱处理后峰值达到0.490 mg·g^-1 FM；游离脯氨酸与可溶性糖在干旱胁迫下逐渐累积, 500 mg·L^-1甜菜碱处理分别为2.878 mg·g^-1 FM和37.6 mg·g^-1 FM,均低于单纯胁迫及100 mg·L^-1甜菜碱处理；可溶性蛋白质含量在水分胁迫下呈下降趋势,甜菜碱处理后最小值为4.03 mg·g^-1 FM,较单纯胁迫下的最低值（3.14 mg·g^-1 FM）高20.3%.表明叶面喷施甜菜碱能在一定程度上减轻桃树的受害程度,提高其抗旱性.

Effects of exogenous betaine on physiological responses of peach tree under water stress

With four-year-old potted Prunus persica L. cv. Qingfeng as test material, this paper studied the change pattern of its leaf betaine content under water stress, and its physiological responses under effects of foliage-spraying exogenous betaine. The results showed that under normal water supply, the betaine content in Qingfeng' s leaf was 75.9-80.5 microg x g(-1) FM, which was increased with increasing water stress, and up to 278.9 microg x g(-1) FM on the 16th day after cutting off the water supply. The leaf plasma membrane permeability was 8.06% - 8.61% under normal water supply, but increased to 28.62% under water stress. When 100 and 500 mg x L(-1) of betaine were applied exogenously, the plasma membrane permeability was 26.25% and 21.79% after 16 days, respectively. The hydrogen peroxide (H2O2) content increased from 27.2-32.5 micromol g(-1) FM to 76.4 micromol x g(-1) FM in the course of water stress, and decreased to 73.2 and 68.5 micromol x g(-1) FM after spraying 100 and 500 mg betaine x L(-1), respectively. During the period of intensified water stress, the peak value of ascorbate peroxidase (AsA-POD) activity was 0.435 mg x g(-1) FM, and up to 0.490 mg x g(-1) FM when treated with exogenous betaine. When the peach tree was subjected to water stress, the contents of free proline and soluble sugar accumulated dramatically, but produced on approximately decrease in 500 mg x L(-1) endogenous betaine application on the 16th day which was slightly less than that of control and 100 mg x L(-1) betaine application. There was a gradual decline in the content of soluble protein under water stress, and an increment of 20. 3% was observed when betaine was applied exogenously. These results strongly suggested that foliage-spraying exogenous betaine could increase the drought resistance of peach tree through decreasing its leaf plasma membrane permeability and H2O2, free proline and soluble sugar contents and increasing its leaf AsA-POD activity and soluble protein content.