酸雨胁迫下镧对水稻种子萌发及呼吸作用的影响

Effects of Lanthanum on Germination and Respiration of Rice Seeds under Acid Rain Stress

采用胁迫强度为pH2．0，2．5，3．0，3．5，4．0，4．5，5．0的模拟酸雨和具显效剂量的稀土镧[La（Ⅲ）]复合处理水稻种子，置于常温下萌发，测定镧对不同酸雨胁迫强度下种子萌发和呼吸指标的影响。结果表明，1．0mg／L的La（Ⅲ）溶液浸种对水稻种子萌发有稳定促进作用，被确定为显效剂量。在高强度酸雨（pH2．0～2．5）胁迫下，水稻种子的各项萌发指标均为0，低强度酸雨（pH3．0～5．0）对种子萌发影响较小，当胁强为pH2．0时，La（Ⅲ）浸种无明显效果，胁强为pH2．5时，La（Ⅲ）浸种能促进部分水稻种子萌发，胁强为pH4．0时，La（Ⅲ）浸种处理的各项萌发指标接近或超过对照，促进作用较明显。进一步测定La（Ⅲ）对特定剂量酸雨胁迫下呼吸作用的影响表明，经La（Ⅲ）浸种后种子呼吸速率显著增强，呼吸商更接近1。由此可见，La（Ⅲ）对种子萌发的促进作用可能与La（Ⅲ）浸种能提高种子呼吸速率，增加糖类呼吸基质等有关。

The effects of Lanthanum （ La （Ⅲ） ） on germination and respiration of rice seeds under acid rain （AR） stress were studied with seven simulated AR concentrations of pH 2.0, 2.5, 3.0, 3.5, 4.0,4.5 and 5.0 and a dominant dosage of La （Ⅲ）. The results showed that 1.0 mg/L of La （Ⅲ） solution had a marked stable and pro- moting effect on seed germination among the seven concentrations from 0.5 to 30.0 mg/L of La （IIl） , thus it was designated as the dominant dosage. When the seeds were treated only with AR, no seed germination occurred under the stress of pH 2.0 - 2.5 AR, but when the seeds were treated with the stress of pH 3.0 - 5.0 AR, the seed ger- mination was little affected. When the seeds were treated by AR with La （Ⅲ）, it was found that La （Ⅲ） had a certain promoting effect on seed germination at the pH 2.5 AR stress intensity, and all germination indexes recov- ered as close to or even higher than those of the controls at pH 4.0 AR stress intensity, indicating a remarkable effect of La （Ⅲ） on enhancing germination of seeds. The results of respiration tests of the treatments showed that the treatments by soaking seeds with La （[II ） had a significantly higher respiratory rate than those without La （Ⅲ）, and their respiratory quotients were closer to 1, indicating that the promoting effect of La （Ill） on seed ger- mination could be related to increase of respiratory rate and strengthening of the capacity of using carbohydrates.