两种暖季型草坪禾草对土壤持续干旱胁迫的生理反应

在土壤含水量不断递减的干旱胁迫条件下,对沟叶结缕草、假俭草的生理反应进行研究.结果表明,恢复供水试验显示,沟叶结缕草的抗旱能力大于假俭草;随胁迫加深,叶片含水量不断下降,水分饱和亏缺增加;脯氨酸(Pro)含量先升后降,但沟叶结缕草的高峰期出现较假俭草迟且含量高,因而可以Pro高峰期出现的早迟及含量高低作为判定抗旱能力的指标之一;根系活力胁迫初期高于对照,以后逐渐下降,但沟叶结缕草维持高水平时间较长;胁迫初期叶片质膜透性(RPP)、丙二醛(MDA)表现为缓慢递增,SOD活性高于对照,当胁迫到一定程度后,RPP、MDA急剧增加,SOD活性急剧下降,但沟叶结缕草能在较长时间内维持SOD活性,RPP、MDA增加幅度较小,这是沟叶结缕草较假俭草抗旱的生理机制之一.

Physiological responses of two warm-season turf grasses to persistent soil drought stress

The physiological responses of Zoysia matrella and Eremochloa ophiuroides to progressively decreasing soil moisture were studied. The renewing-water supply experiment showed that Z. matrella had greater drought resistance than E. ophiuroides. With declining soil moisture, leaf water content continually decreased and water saturation deficit increased. Proline (Pro) content increased initially then decreased, but the Pro content peak of Z. matrella occurred later and was higher than E. ophiuroides. Therefore the relative appearance time of the Pro content peak, and its Pro content amount are two indices for determining drought resistance. During the initial stress period, root viability was higher than the control. With increased stress, root viability gradually decreased, but Z. matrella maintained a high level for a longer time. During the initial stress period, leaf protoplasmic membrane penetration (RPP) and MDA increased slowly, and leaf SOD activity was higher than the control. When drought stress reached a certain degree, RPP and MDA sharply increased, but SOD activity sharply decreased. However, relative to E. ophiuroides, Z. matrella maintained SOD activity for a longer time, and the increase extent of RPP and MDA was less. This is one of the physiological mechanisms giving (Z. matrella) greater drought resistance than E. ophiuroides.