3种乡土园林地被植物对干旱胁迫的生理响应

为了更好地开发利用小叶蚊母Distylium buxifolium,厚皮香Ternstroemia gymnanthera和轮叶蒲桃Syzygium grijsii等3种优新乡土园林地被植物,采用盆栽试验研究了3种植物2年生幼苗对适宜水分、轻度干旱、中度干旱和重度干旱(土壤田间持水量的75%~80%,55%~60%,40%~45%和30%~35%)条件下的生理响应。结果表明:随着干旱胁迫程度的增加,3个树种的叶片相对含水量、叶绿素质量分数急剧下降;叶片细胞膜透性和丙二醛(MDA)质量分数急剧上升(P<0.05);游离脯氨酸、可溶性糖和可溶性蛋白质等渗透调节物质质量分数快速上升,其中游离脯氨酸对抵御干旱起到重要的渗透调节作用。小叶蚊母叶片超氧化物歧化酶(SOD),过氧化物酶(POD)和过氧化氢酶(CAT)活性显著升高(P<0.05),表明小叶蚊母对干旱的主动响应调节能力较强;而轮叶蒲桃和厚皮香先上升,在重度干旱胁迫后下降,这时可能达到植物耐受干旱的极限,清除氧自由基的能力降低。通过隶属函数法分析得出3种乡土园林地被植物的抗旱性强弱顺序为小叶蚊母> 厚皮香> 轮叶蒲桃。

Physiological response of three native garden ground cover plant seedlings to increasing drought stress

To develop and utilize three native garden ground cover plants (Distylium buxifolium, Ternstroemia gymnanthera, and Syzygium grijsii), a water controlling experiment was conducted to measure the physiological responses of soil water conditions to differing soil water contents:suitable soil moisture (field moisture capacity of 75%-80%), mild drought (55%-60%), medium drought (40%-45%), and severe drought (30%-35%). A subordinate function method was used to rank drought-resistance. Results showed that as drought stress increased, the content of leaf relative water and chlorophyll for the three plants decreased rapidly, but membrane permeability and malondialdehyde (MDA) content increased rapidly. The content of free proline, soluble sugar, and soluble protein increased with free proline playing a key role in resisting drought stress. With an increase in drought stress, the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity of D. buxifolium increased; however, T. gymnanthera and S. grijsii only increased with suitable soil moisture to medium drought conditions, and decreased with severe drought. The subordinate function method ranking drought-resistance was D. buxifolium > T. gymnanthera > S. grijsii. Thus, D. buxifolium could conduct physiological regulation by antioxidant enzyme systems; whereas T. gymnanthera and S. grijsii reached a tolerable limit where the ability to scavenge oxygen free radicals decreased rapidly.