火龙果幼苗和成龄树寒害指标初探

Indices of Chilling Injury for Pitaya Seedling and Mature Plant

以火龙果品种"紫红龙"(Hylocereus polyrhizus Briton&Rose)幼苗和6a生成龄树为试验材料,在开花期置于人工气候室,以20℃为对照,设置2、0、-2、-4、-6℃共5个低温处理对其胁迫12h后取枝条测定相对电导率、丙二醛(MDA)、超氧化岐化酶(SOD)和可溶性蛋白质等抗寒性生理生化指标,探讨各项指标与温度间的定量关系,结合寒害症状观察,确定火龙果树的寒害温度指标。试验结果表明:火龙果幼苗和成龄树的枝条分别在0℃和-2℃下表现出明显的寒害症状,随着处理温度的继续降低,症状更为明显,在-4℃下均死亡。随着处理温度降低,幼苗和成龄树相对电导率和MDA含量逐渐升高,SOD活性和可溶性蛋白含量先升高后降低。利用电导法配以Logistic方程求得幼苗和成龄树的半致死温度分别为-1.7℃左右和-2.2℃左右。低温使火龙果幼苗和成龄树受到伤害,且温度越低,受害越严重,成龄树抗寒能力比幼苗强。研究结果可为火龙果寒害防御、种植区划和相关研究提供科学依据。

Taking seedlings and 6-year trees of variety Zihonglong （ Hylocereus polyrhizus Briton ＆ Rose） as materials, five artificial environmental control experiments and one basis experiment were conducted in artificial climate chamber in September, 2012. The control experiment temperature was 2, 0, - 2, - 4 and - 6℃, respectively, and the basis experiment was 20℃. At each experiment, relative electrical conductivity （ REC）, MDA content, SOD activity and soluble protein content of pitaya branch were measured after treatment 12 hours, and morphological changes were observed at the same time, in order to investigate the relationship between the factors and temperature and find the indices of chilling injury for pitaya. The results showed that seedlings and 6-year trees damaged obvious at 0℃ and - 2℃ respectively. The lower temperature was, the more obvious injury symptoms came out. REC and MDA content increased with temperature decline. SOD activity and soluble protein content increased at beginning and then decreased. The Logistic Model was used to fit the sigmoid curve between REC from plant tissues and temperature of treatments. Then the semi-lethal temperature, which was - 1.7℃ and -2.2℃, was determined by the model. The results indicated that the semi-lethal temperature of seedlings and 6-year trees were about - 1.7℃ and - 2.2℃, respectively. Low temperature damaged both seedlings and 6-year trees, and the lower temperature was, the more badly injury would get. 6-year trees could tolerate lower temperature than seedling. The results could provide scientific basis for chilling injury prevention and planting division of pitaya.