3个品种水稻种子萌发对酸雨胁迫的响应

Response of three varieties of rice seeds to the acid rain stress in the germination process

为了探索不同水稻种植区水稻品种对酸雨胁迫的响应规律,采用室内实验方法研究pH值为2.0、2.5、3.0、3.5、4.0、5.0的模拟酸雨对隆安优8、天协1、协优57水稻品种种子发芽率、发芽势、发芽指数、活力指数和异状发芽率5个指标的影响。结果表明:酸雨持续胁迫7d后,上述3个品种的发芽势(率)、发芽(活力)指数随胁迫强度增加(pH值为5.0～3.0)呈先增后减的变化,pH值为2.5时种子仅有异状发芽,pH值为2.O时均不发芽;3者的发芽势(率)、发芽(活力)指数等均与胁迫时间(1～7d)呈显著负相关(异状发芽率呈正相关)。综合分析认为,酸雨对3个水稻品种的伤害阈限为pH值2.5～3.5;一定胁强(pH值为2.5)下,3类种子上述5项萌发指标与CK呈显著差异的胁时不同:隆安优8、协优57(4 d,2 d,2 d,2 d,4 d)大于或等天协1(3 d,2 d,2 d,2 d,3 d),表明3者对酸雨的抗性存在一定差异,即隆安优8、协优57大于天协1。

This paper has provided its investigation and experimental findings over the effects of the acid rain stress on the following three varieties of rice （ O. sativa ） seed germination. The said three varieties of rice are known as Longanyou 8, Tianxie 1 , Xieyou 57. The purpose of our research was to explore the corresponding response regularities of different rice varieties to acid rain. In doing our experiments, we have adopted six simulated acid rain （SAR） solutions, i. e. those of the pH 2.0, 2.5, 3.0, 3.5, 4.0, and 5.0, and neutral solution as the contrast group. As the first step, we placed the pretreated seeds of the above mentioned rice varieties into culture dishes with filter sheets, letting them germinate in a cultivated container at a constant temperature of 25 ℃ , in which each group to be treated involved three dishes with 50 seeds in each, respectively. In germinalion process, the seeds were let to be exposed to the simulated acid rain that was replaced everyday. Then, the percentage germination, germination energy, germination index, the vigor index, as well as the percentage of abnormal germination were tested and measured under the acid rain stress. The results of our experiments show that the percentage germination, germination energy, germination index, vigor index of the three seed-varleties initially increased and then decreased with the decrease of pH value from 5.0 to 3.0. The rice seeds were found to germinate only abnormally at pH 2.5 and failed to shoot up at pH 2.0. Furthermore, significant negative correlation was found among the above said indexes, though a positive correlation was found to exist between the stress time （1 -7 d） and the percentage of abnormal germination. This also shows that the germination threshold values of three seeds were all standing between pH 2.5 and 3.5. However, the stress time of Longanyou 8 and Xieyou under the condition, when the difference of the above said five indices between each treatment and the contrast group became significant 57 （4 d, 2 d, 2 d, 2 d, 4 d） proved longer than that of Tianxie 1（3 d, 2 d, 2 d, 2 d, 3 d）. Thus, the experimental data further prove that the three varieties of rice would reveal different degrees of sensitivity under acid rain stress, with Longanyou 8 and Xieyou 57 being stronger in their resistance than with Tianxiel.