土壤萘污染对玉米苗期生长和生理的影响

Soil Naphthaline Pollution Stress on Corn(Zea mays L.)Seedling Physiological Effect

以玉米幼苗为实验材料,研究了不同浓度的土壤萘污染对其生理指标和生长发育的影响。结果表明,土壤萘污染浓度小于50mg·kg-1时对玉米地上部分的生长发育有促进作用,对根部的影响是污染初期有促进作用,但随着处理时间的增加则抑制根部的生理活动。土壤萘污染浓度为100～150mg·kg-1时,第1周时对玉米的生长发育也有促进作用,第2周开始抑制玉米的生长发育。当土壤萘污染浓度大于200mg·kg-1时,污染胁迫作用对玉米幼苗生长发育的影响明显。研究证实,高浓度污染的胁迫能使幼苗体内蓄积大量的活性氧和超氧自由基,破坏了其脂膜和代谢所需的蛋白酶,导致生理指标活动发生变化和代谢系统的紊乱。各项生理指标的变化表明,玉米苗期第2周是对萘污染进行生理调节和适应的关键时期。

The effect of soil naphthaline pollution on growth of maize seedlings was investigated in this paper. We found that the influence of soil naphthaline pollution stress on content of Chlorophyll was not obvious, but the negative influence on Chlorophyll b was stronger than on Chlorophyll a. The inhibition on photosynthetic rate by soil uaphthaline pollution was much stronger than on the content of Chlorophyll. We found that both the upper and under-ground parts of maize plants were sensitive to soil naphthaline pollution. At a lower concentration （50 mg.kg^-1 ）, the pollution stimulated growth of both the above-ground plants and their roots, though this stimulating effect diminished and followed by inhibiting effect after a longer treatment. At higher concentrations （ 100-150 mg.kg^-1 ）, the soil naphthaline pollution still exhibited a stimulating effect on the growth and development of the maize seedlings in first week, but became inhibitory starting from the second week. When the concentration was above 200 mg.kg^-1, the soil naphthaline pollution seriously restrained maize development, probably due to accumulating of a large amount of reactive oxygen and superoxide radicals. Reactive oxygen and superoxide radicals might damage the panniculus adiposus and proteases that were essential for normal metabolism. Thus, our results indicated that the second week was the key period for physiologic accommodation and adaptation of the maize seedlings to soil naphthaline pollution.