镧对西葫芦种子酸雨胁迫的缓解效应

Alleviative Effects of LaCl_3 on Acid Rain Stresses for Cucurbita pepo Seed Germination

研究了镧对酸雨胁迫下西葫芦种子萌发状况及活性氧代谢的影响。结果显示,经12mg/L LaCl3浸种后,可明显缓解酸雨对西葫芦种子萌发的抑制作用,pH3.5时效应最显著,种子的发芽率、发芽势、发芽指数和活力指数显著升高,并接近于对照;pH3.0时也有明显改善,但达不到对照水平;在pH2.5时,发芽状况没有明显改变,仍只有少数种子能萌发。同时,镧处理能显著减少强酸雨对抗氧化酶的破坏,缓和MDA的积累。上述结果表明,镧浸种可通过调节抗氧化酶活性,缓解酸雨对种子萌发的抑制作用;但活性氧代谢的改进必须达到其阈值,否则就没有生长促进效应。因此,这类指标的数值不能直接用于抗逆性评价。

To test and evaluate the alleviative effects of LaCl3 on acid rain（AR） stresses for Cucurbita pepo seed,the germination and activate oxygen metabolism of C.pepo seeds soaked by LaCl3 solution（12 mg/L） were studied under different AR stresses.The results showed that the damage on seed germination from AR will be alleviated.Under the weak AR stress（pH=3.5）,the germination indexes（germination rate,germination potential,germination index and vigor index） were all higher than untreated seeds,and recovered as close to those of the control.Under the medium AR stress（pH=3.0）,the four indexes were higher than untreated ones,but can not recover to the control level.Under the higher AR stress（pH=2.5）,the four indexes were not obvious improvement,still only a few seeds can be germinated.In other hand,the destructions of SOD,POD and CAT can be reduced notably,accumulation of MDA was relaxed in soaked seeds at pH≤3.0;but these indexes did not change obviously at pH≥3.5.These indicated that LaCl3 probably alleviates AR damage on seed germination by some antioxidant enzyme activity adjustment.However,the active oxygen metabolism improvement must reach its threshold value,otherwise it can not promote the seed germination.Thus,the value of these indicators can not be directly used for resistance evaluation.