【作者】 杨峰；

【导师】 胡景江；

【作者基本信息】 西北农林科技大学 ， 植物学， 2007， 硕士

【摘要】 本研究以1年生“红富士”苹果幼苗为试验材料,采用盆栽控水的方法,研究了水分胁迫条件下外源壳聚糖(CTS)、水杨酸(SA)和多胺(精胺,Spm)对苹果幼苗生长及抗旱性的效应。通过对生长以及光合速率、有机渗透调节物含量、保护酶活性、叶片质膜相对透性以及膜脂过氧化产物丙二醛(MDA)的含量等指标的测定分析,确定了外源CTS、SA和Spm的适宜施用浓度,比较三种外源物质在适宜浓度下对苹果幼苗抗旱性的影响,探讨了CTS、SA和Spm提高苹果幼苗抗旱性的可能机制。主要研究结果如下:1、干旱条件下外源CTS、SA和Spm能维持苹果幼苗的正常代谢水平,促进生长,提高抗旱性。在中度干旱条件下苹果幼苗的叶绿素含量及光合速率降低,幼苗的株高生长和茎增粗均受到明显抑制,与正常水分对照相比株高净增长量降低了26.68%,茎粗净增长量降低了27.59%。外源CTS、SA和Spm均能提高叶绿素含量,维持光合能力,促进生长,其效果达到接近或超过正常水平。2、干旱条件下外源CTS、SA和Spm能维持或提高保护酶(SOD、CAT)活性,降低MDA含量和质膜相对透性,防止或降低细胞膜脂过氧化程度。同时促进可溶性糖和游离脯氨酸等有机渗透调节物质的积累,增强渗透调节能力,维持正常代谢水平,提高抗旱性。3、CTS、SA和Spm对苹果幼苗生长及抗旱性的效应与浓度有关,一定范围内随CTS浓度增加其效应增强,适宜浓度为100mg/L,再增大浓度其作用效果不再增大。而SA和Spm对苹果幼苗生长及抗旱性的效应随其浓度由低到高呈现出先升后降的趋势,他们的最适浓度分别为0.1mmol/L和10μmol/L,但SA在降低膜透性和膜脂过氧化方面效果不明显。由此表明,适宜浓度的CTS、SA和Spm能够提高苹果幼苗在水分胁迫条件下生长及抗旱性,低浓度的SA和Spm抗旱效果不显著,浓度过高可能又存在抑制作用,而CTS浓度增大到一定程度抗旱效果不再增大。4、干旱条件下CTS、SA和Spm在促进苹果幼苗生长及提高抗旱性的效应上三者之间存在着一定的差异,但差异不显著。CTS和SA在复水之前比较好,而Spm在复水后再胁迫效果较好。更多还原

【Abstract】 In this study, apple seedlings of a year-old Red Fuji were used as experimental material, the effects of exogenous Chitosan(CTS), Salicylic acid(SA) and Polyamines (Spermine, Spm) on growth and drought resistance of apple seedlings were studied by the pot-culture of water control. Changes of seedlings growth, photosynthetic rate, content of osmotic adjustment substances, activities of protective enzymes, relative permeability of plasma membrane and content of Malondialdehyde (MDA) were determined respectively under moderate water stress in order to ascertain the optimum concentration of CTS, SA and Spm on enhancing drought resistance of apple seedlings, compare the effects of the three exogenous matters on enhancing drought of apple seedlings, and discuss the mechanism of CTS, SA and Spm to enhance the drought resistance of apple seedlings. The results were as follows:1. Under water stress, treatmeat with exogenous CTS, SA and Spm on apple seedlings could maintain normal metabolism, promote plant growth and enhance drought resistace of the apple seedings. Under moderate drought conditions, content of chlorophyll and photosynthetic rate of apple seedlings were decreased, the growth of plant height and increase of stem-diameter were significantly inhibited. Comparing with the control of normal water,net increase of stem height and stem diameter were decreased respectively about 26.68% and 27.59%. Exogenous CTS, SA and Spm were able to increase content of chlorophyll, maintain photosynthetic rate and promote growth rate of seedlings, its effects were close to or above the normal.2. Exogenous CTS, SA and Spm could maintain or increase the activities of protective enzymes(SOD,CAT), decrease content of MDA and relative permeability of plasma membrane, prevent or decrease peroxidative degree of plasma membrane.At the same time , accumulations of organic osmotic substances that soluble sugar and free praline were increased, osmotic adjustment ability was enhanced, normal metabolism of apple seedlings was maintained, and drought resistance was increased.3. The effects of CTS, SA and Spm on growth and drought resistance of apple seedlings have relation to the concentration, the effect would enhance when the concentration of CTS increase within a certain rang, the best concentratin was 100mg/L. If the concentration continued to increase it’s effects would not enhance. And the effects were increased firstly and then decreased with the SA and Spm concentration from low to high, the best concentration of SA and Spm respectively were 0.1mmol/L and 10μmol/L, but the effect of SA on decreasing relative permeability of plasma membrane and membrane lipid peroxidation of apple seedlings was not significant. The results showed that the optimum concentration of CTS, SA and Spm could enhance growth and drought resistance of apple seedlings under water stress, but there was no significant when treated with the low concentration SA and Spm on apple seedlings, and the high concentration had inhibition, when the concentration of CTS was up to a value, it’s effects would not enhance.4. Under water stress, there were some differences in the effects of the optimum concentration of CTS, SA and Spm on enhancing growth and drought resistance of apple seedlings, but no significant. The effects of CTS and SA on drought resistance were better before rewatering of water stress, but the better effect of Spm was in the after rewatering of water stress and then stress again.更多还原