Effect of brassonolide on water physiology of Hippophae rhamnoides L. and Amorpha fruticosa L.

Chinese. 为了探讨油菜素内酯对林木抗旱水分生理特性的影响，采用盆栽试验，在控水条件下用蘸根和叶面喷施不同质量浓度油菜素内酯的方法，对黄土丘陵区主要造林树种沙棘和紫穗槐苗木的水分状况进行了测定和分析。结果表明，在重度干旱（土壤含水量7%～8%）条件下， 0.1～0.4 mg/L油菜素内酯处理的沙棘苗清晨叶水势均显著高于对照（清水处理）； 0.2～0.4 mg/L油菜素内酯处理的沙棘苗叶片含水量、相对含水量较对照显著提高，而水分饱和亏较对照显著降低。在轻度干旱（土壤含水量12%～13%）和重度干旱条件下，0.1～0.4 mg/L油菜素内酯处理的紫穗槐苗清晨叶水势均显著高于对照；在适宜水分（土壤含水量17%~18%）和重度干旱条件下，0.1 mg/L油菜素内酯处理的紫穗槐苗叶片含水量较对照显著升高；在重度干旱条件下，0.2～0.4 mg/L油菜素内酯处理的紫穗槐苗叶片含水量、相对含水量较对照显著提高。在适宜水分、轻度干旱及重度干旱条件下，0.2和0.3 mg/L油菜素内酯处理的沙棘和紫穗槐苗午间平均蒸腾速率均较对照显著降低。在重度干旱条件下，0.1～0.4 mg/L油菜素内酯处理的沙棘和紫穗槐苗在饱和含水量时的最大渗透势（ψπ100）和膨压为0时的渗透势（ψπ0）均较对照显著降低；ψπ100和ψπ0的差值仅用0.1和0.2 mg/L油菜素内酯处理的紫穗槐苗较对照显著降低；膨压为0时的相对含水量（RWC0）和渗透水含量（ROWC0）仅用0.2 mg/L油菜素内酯处理的紫穗槐苗显著降低。以上结果表明，0.1～0.4 mg/L油菜素内酯处理改善了干旱胁迫下沙棘和紫穗槐苗木的缺水状况，提高了两种苗木的抗旱能力。

English. In order to discuss effects of brassinolide on drought-resistant water physiology of tree, the water status of Hippophae rhamnoides L. and Amorpha fruticosa L. seedlings were measurated and analyzed by controlling soil water and dipping roots and spraying leaves of two species seedlings with different concentrations of brassinolide under potted condition. The results showed after 0.1-0.4 mg/L brassinolide treatments the leaf water potentials in early morning of Hippophae rhamnoides L. seedlings were under severe drought (soil moisture 7%-8%) and Amorpha fruticosa L. under light drought (soil moisture 12%-13%), and severe drought were higher than untreated ones significantly. For Hippophae rhamnoides L. seedlings with 0.2-0.4 mg/L brassinolide treatments, the leaf water content and relative water content were increased under severe drought and water saturated deficiency was decreased remarkably. For Amorpha fruticosa L. seedlings with 0.1 mg/L brassinolide treatment the leaf water content was significantly increased under adequate soil water (soil moisture 17%-18%) and severe drought compared with untreated one and the relative water content was increased and water saturated deficiency was decreased significatly when treated with 0.2-0.4 mg/L brassinolide and under severe drought. Under adequate soil water, light and severe drought noontime mean transpiration rates of Hippophae rhamnoides L. and Amorpha fruticosa L. seedlings with 0.2 and 0.3 mg/L brassinolide treatments were significantly decreased compared with untreated one. Under severe drought the ψπ100 and ψπ0 of Hippophae rhamnoides L. and Amorpha fruticosa L. seedlings with 0.1-0.4 mg/L brassinolide treatments were significantly decreased compared with untreated one.Under severe drought the difference between ψπ100 and ψπ0 was decreased significantly only when Amorpha fruticosa L.seedlings was treated by 0.1 and 0.2 mg/L brassinolide. Under severe drought the RWC0 and ROWC0 were significantly decreased only when Amorpha fruticosa L. seedlings was treated by 0.2 mg/L brassinolide. The lack of water in Hippophae rhamnoides L. and Amorpha fruticosa L.seedlings treated with 0.1-0.4 mg/L brassinolide was improved under drought stress. The treatment enhanced the drought resistance of two seedlings.