干旱胁迫下结缕草叶片抗坏血酸与相关生理指标变化的品种差异研究

A study on the changes of ascorbic acid and related physiological indexes in different cultivars of Zoysia under drought stress

通过盆栽试验,以日本结缕草与细叶结缕草为材料,研究了干旱胁迫下结缕草叶片AsA含量与相关生理指标的品种差异。结果表明,干旱胁迫下日本结缕草和细叶结缕草叶片中AsA含量与相关生理指标的动态变化规律基本相似,但品种间差异显著。干旱胁迫下2个品种的AsA含量和AsA/DHA均呈现先上升后下降的变化趋势,但日本结缕草下降的时间更早。干旱胁迫下叶片相对含水量、POD活性在2个品种中均呈下降趋势,但日本结缕草的下降趋势更明显,尤其在干旱胁迫后期。胁迫后日本结缕草叶绿素a与叶绿素b含量下降明显,而细叶结缕草变化不大。胁迫后两者的相对电导率和MDA含量均呈上升趋势,但日本结缕草增加的幅度更为显著。干旱胁迫后日本结缕草和细叶结缕草叶片Rubisco的含量均在第3天开始下降,胁迫后期日本结缕草Rubisco含量恢复到对照水平,而细叶结缕草Rubisco含量在胁迫后期显著高于对照。本研究结果表明,干旱胁迫下结缕草可以通过增加和维持叶片中AsA含量与POD活性来减缓Rubisco及叶绿素的降解,降低干旱胁迫对植株造成的氧化胁迫伤害程度,进而改善其抗旱能力。本研究结果进一步证实结缕草抗旱能力有品种差异,其中日本结缕草抗旱能力弱于细叶结缕草。

The changes of foliar ascorbic acid and related physiological indexes in Zoysia japonica and Z. tenuifolia under drought stress were studied in a pot trial. The results showed that the dynamic change rules of foliar ascorbic acid and related physiological indexes were similar in Z. japonica and Z. tenuifolia under drought stress, but significant differences were still observed in these two cultivars. For example, the level and redox status of ascorbic acid decreased at the later drough in these two cultivars were increased at the early drought stress stages, and then t stress stages, but the decreased time was earlier in Z. japonica compared with Z. tenuifolia. Downtrend of leaf relative water content and peroxidase （POD） activity were found under drought stress in these two cultivars, but the downtrend in Z. japonica was more significant, especially at the later drought stress stages. In addition, the decreases of chlorophyll a and b were significant in Z. japonica but not in Z. tenuifolia under drought stress. Moreover, downtrend of the leaf relative electric conductivity and MDA content were also found in these two cultivars under drought stress, but the downtrend in Z. japonica was more significant. On the other hand, the Rubisco contents decreased on the 3rd day under drought stress in these two cultivars, and no significant difference in the level of Rubisco was observed in Z. japonica relative to the control at the later stages of drought stress, while the difference was significant in Z. tenuifi）lia. All these results showed that the increase of foliar ascorbic acid and POD activity in Zoysia under drought stress may delay the degradation of Rubisco and chlorophyll content and relieve the injury caused by oxidative stress and improve the drought-resistance. These results also confirmed that there are some drought-resistant difference between different Zoysia cultivars and the drought-resistant of Z. japonica is lower than Z. tenuifolia