铝毒和低磷胁迫对水稻幼苗生长·根系有机酸分泌的影响

[目的]为明确低磷、铝毒单独及复合胁迫下,不同水稻品种生理响应的差异。[方法]采用营养液培养试验,以秀水132(耐铝型)和甬优8号(铝敏感型)为材料,研究了各胁迫下幼苗干物质积累、光合能力和根系有机酸分泌量。[结果]低磷、铝毒胁迫下根系和地上部干重、叶绿素含量、光合速率、气孔导度和蒸腾速率均显著下降。低磷铝毒复合胁迫下幼苗干重及光合参数值均显著低于单一胁迫处理;酒石酸、苹果酸、柠檬酸和乙酸是根系各处理下分泌的主要有机酸。低磷、铝毒胁迫下根系乙酸、苹果酸和柠檬酸分泌量增加,复合胁迫时根系3种有机酸的分泌量高于单一胁迫处理。低磷、铝毒胁迫下水稻幼苗干重、光合能力及根系有机酸分泌存在显著的基因型差异。各胁迫下甬优8号植株干重和光合参数的下降幅度高于秀水132,而秀水132根系有机酸分泌量的增幅大于甬优8号。[结论]低磷铝毒复合胁迫引发水稻幼苗更严重的生理代谢抑制,以甬优8号表现更明显;复合胁迫下根系有机酸分泌量高于单一胁迫,以秀水132增幅更大。

Effect of Aluminum Toxicity and Phosphorus Deficiency on Seedlings Growth and Secretion of Organic Acid from Roots

[Objective] The experiment was focused on the physiological response of two rice genotypes differing in Al tolerance to the treatments of phosphorus （P） deficiency and aluminum （Al） toxicity single and combinationed stresses.[Method] Hydroponic experiment was andertaken to study the seedlings growth,photosynthetic capacity and secretion of organic acid （OA） in the roots of rice cultivars exposed to the stress solution.[Result] P deficiency and Al toxicity both inhibited plants dry matter accumulation,significantly decreased chlorophyll content,photosynthetic rate,stomatic conductance and transpiration rate.P deficiency aggravated Al toxicity to the dry matter accumuiation and photosynthetic capacity of rice seedlings.Tartaric acid malic acid,citric acid and acetic acid were the main OA secreted by rice roots irrespective of treatments.The secretions of malic acid,citric acid and acetic acid increased under P deficiency or Al stress,and the secretions were promoted when both excessive Al and P deficiency were present.There was significant cultivars difference in seedlings growth and OA secretion in response to P deficiency and Al toxicity,thus more severe growth inhibition was observed in Yongyou 8,while more OA secretion was detected in Xiushui 132.[Conclusion] Combination of Al and low P caused serious disturbance of physiological metabolisms,especially for Yongyou 8.Further,it induced powerful OA secretion and the more was observed in Xiushui 132.