不同种源赤皮青冈幼苗生长和生理特性对干旱胁迫的响应

Response of growth and physiological characteristics of Cyclobalanopsis gilva seedlings from different provenances to drought stress

以浙江庆元、湖南洞口和湖南靖县3个地理种源的赤皮青冈(Cyclobalanopsis gilva)1年生幼苗为试验材料,采用盆栽称重法控制土壤水分含量,研究了不同程度干旱胁迫对赤皮青冈幼苗生长、生物量分配、叶片自由水和束缚水含量、根系活力和叶片内源激素含量的影响,旨在揭示赤皮青冈幼苗对干旱胁迫的适应机制。结果表明:随着干旱程度的增强,3个种源赤皮青冈幼苗的株高生长量和地径生长量呈下降的趋势;幼苗地上部分和根部生物量增量呈下降的趋势;叶片自由水/束缚水比值降低,束缚水含量升高,而自由水含量的变化趋势不一致;干旱胁迫提高了湖南洞口和湖南靖县种源赤皮青冈的根系活力,但浙江庆元赤皮青冈的根系活力随着胁迫的增强而降低;随着干旱的加剧,3个种源赤皮青冈叶片赤霉素、油菜素内酯、吲哚乙酸和玉米素含量呈降低的趋势,而脱落酸和茉莉酸甲酯含量为升高的趋势。隶属函数值法综合评价结果显示,3个地理种源赤皮青冈抗旱能力由强到弱的顺序依次为:湖南洞口种源>湖南靖县种源>浙江庆元种源。本研究表明,赤皮青冈通过减小生长量、增大根部生物量积累来适应干旱的环境,而较高的束缚水含量、生长素(吲哚乙酸)、细胞分裂素(玉米素和油菜素内酯)和赤霉素含量降低,脱落酸和茉莉酸甲酯含量升高是其抗旱的生理基础。

Using a pot culture experiment, the response of one-year-old seedlings of Cyclobalanopsis gilva from three provenances to drought stress was assessed to understand the adaptation mechanisms of C. gilva to drought stress. The seedlings originating from Qingyuan of Zhejiang Province, and Dongkou and Jingxian of Hunan Province were observed for their growth and physiological properties in this experiment. The growth, biomass production and allocation, free water and bound water and endogenous hormone contents of leaves, and root vitality of the seedlings were measured. The results showed that as the drought stress increased, the increment of height and stem diameter and the increment of aboveground biomass and root biomass of the seedlings had a trend of decrease, and the ratio of free water to bound water of leaves decreased gradually, while the bound water content increased for all three provenances. However, the changes in free water content did not show a consistent trend. Moreover, the drought stress led to an increase in root vitality of the seedlings from Dongkou and Jingxian of Hunan, while a decrease in root vitality of the seedlings from Qingyuan of Zhejiang. In addition, the drought stress resulted in decreases of gibberellins, brassinolide, indole-3acetic acid and zeatins contents and increases of abscisic acid and methyl jasmonate contents of leaves of the seedlings from all three provenances. The subordinate function analysis showed that the seedlings from Dongkou of Hunan had stronger drought resistance than those from Qingyuan of Zhejiang and Jingxian of Hunan. This result implied that C. gilva seedlings became adaptive to drought stress by decreasing the increment of growth and increasing the increment of root biomass. Meanwhile, maintaining a higher bound water content, decreasing auxin （indole3acetic acid）, cytomin （zeatin and brassinolide） and gibberellin contents, and increasing abscisic acid and methyl jasmonate contents, provided the physiological potential of C. gilva＇s to resist drought stress.