种子引发剂氯化胆碱和吲哚丁酸钾对盐胁迫下水稻幼苗生长和生理特性的影响

Effects of Seed Initiators Choline Chloride and Indole-3-butyric Acid Potassium on Growth and Physiological Characteristics of Rice Seedlings Under Salt Stress

为探讨种子引发剂对盐胁迫下水稻幼苗生长及生理特性的影响机制,以杂交稻湘两优900和常规稻黄华占为材料,研究引发剂氯化胆碱(CC)和吲哚丁酸钾(IBAK)对盐胁迫下水稻幼苗生长、光合特性、抗氧化代谢及渗透调节的影响。结果表明,盐胁迫抑制水稻幼苗生长,3.0 mg·L^(-1) CC和1.0 mg·L^(-1) IBAK为缓解盐胁迫对水稻幼苗生长抑制的适宜引发浓度,添加引发剂CC的湘两优900根干重显著增加9.64%,而添加引发剂CC和IBAK的黄华占根系总长度、叶面积、地上干重、根干重、壮苗指数分别显著增加24.78%和14.39%、43.06%和36.33%、11.45%和7.43%、34.60%和28.62%、41.89%和33.55%。引发剂CC和IBAK处理可显著提高盐胁迫下两品种水稻叶片的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和叶绿素含量;激活超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性;同时增加抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白和脯氨酸含量;抑制活性氧积累,降低丙二醛(MDA)含量和相对电导率(REC)水平。盐和引发剂处理在两品种水稻抗氧化指标间均存在普遍的交互作用,而形态指标或光合参数间的交互作用在黄华占中更为显著。综上所述,引发剂CC和IBAK主要通过增强抗氧化系统活性、提高渗透调节潜力、降低活性氧损伤来提高水稻幼苗的耐盐性。本研究结果为探明引发剂缓解水稻盐胁迫损伤的作用机理提供了理论依据。

The hybrid rice Xiangliangyou 900 and cultivated rice Huanghuazhan were used as the materials to investigate the effects of two seed initiators,choline chloride(CC)and indole-3-butyric acid potassium salt(IBAK),on the growth and physiological characteristics of rice seedlings under salt stress.In this study,the growth,photosynthetic characteristics,antioxidant metabolism,and osmotic regulation of rice seedlings under salt stress with different concentrations of the initiators were completely analyzed.The results showed that salt stress inhibited the growth of rice seedlings.The priming optimum concentrations for alleviating the growth inhibition of rice seedlings under salt stress were 3.0 mg·L^(-1) CC and 1.0 mg·L^(-1) IBAK.With the addition of initiator CC,the dry weight of Xiangliangyou 900 roots was significantly increased by 9.64%.Adding CC and IBAK significantly increased the total root length,leaf area,shoot dry weight,root dry weight,and seedling index of Huanghuazhan by 24.78%and 14.39%,43.06%and 36.33%,11.45%and 7.43%,34.60%and 28.62%,41.89%and 33.55%,respectively.Moreover,application of the initiator CC and IBAK drastically increased the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),and chlorophyll content of the leaves of the two rice varieties under salt stress,and also significantly activated the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and ascorbate peroxidase(APX).Adding CC and IBAK could also increase the content of ascorbic acid(AsA),glutathione(GSH),soluble protein,and proline,while inhibit the accumulation of reactive oxygen species,and reduce the level of malondialdehyde(MDA)and relative conductivity(REC)of two rice seedlings compared to the NaCl treatment alone.There was a typical interaction between salt and initiator treatments on the antioxidant indexes of the two rice varieties,while the interaction on morphological indexes or photosynthetic parameters of the two rice varieties was more significant in Huanghuazhan.In conclusion,the initiators CC and IBAK can improve the salt tolerance of rice seedlings mainly by enhancing the activity of the antioxidant system,increasing the potential of osmotic regulation,and reducing the damage of reactive oxygen species.This study provided a theoretical basis for the application of initiators to alleviate the damage of salt stress on rice seedlings.