调环酸钙对盐胁迫下水稻幼苗生长及抗性生理的影响

Effects of prohexadione-calcium on growth and resistance physiology of rice seedlings under salt stress

为探讨调环酸钙(prohexadione-calcium,Pro-Ca)对盐胁迫下水稻幼苗的缓解作用,明确Pro-Ca提高水稻耐盐能力的最适浓度,以水稻品种‘黄华占’为试验材料,研究不同浓度(25、50、75、100、125、150mg·L^(-1))Pro-Ca对盐胁迫下水稻幼苗生长及抗性生理的影响。结果表明:盐胁迫抑制水稻正常生长,对水稻抗性生理产生不利影响。外源添加Pro-Ca促进盐胁迫下水稻幼苗的地上部生长,提高根系活力,增强超氧化物歧化酶(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,提高可溶性蛋白和脯氨酸的含量,降低叶片相对电导率及O_(2)^(-)·的产生速率,增加叶片SPAD,提高净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)和表观叶肉导度(AMC)。综合分析,100 mg·L^(-1)浓度处理时效果最好,表现为茎基宽、根系总长度、干质量、净光合速率及CAT等出现最大值。初步推断在盐胁迫下,Pro-Ca通过提高植物抗氧化酶活性、叶绿素含量及渗透调节物质含量,降低幼苗O_(2)^(-)·的产生速率及电解质渗透来保护细胞结构的完整,促进幼苗生长及光合速率的上升,从而增强水稻幼苗耐盐能力。

In order to explore the mitigation effect of prohexadione-calcium(Pro-Ca) on rice seedlings under salt stress, the optimal concentration of Pro-Ca to improve the salt tolerance of rice was determined. The rice variety ‘Huanghuazhan’ was used as the experimental material to study the effects of different concentrations(25, 50, 75, 100, 125, 150 mg·L^(-1)) of Pro-Ca on the growth and resistance physiology of rice seedlings under salt stress. The results showed that salt stress inhibited the normal growth of rice, and adversely affected the resistance physiology of rice. Exogenous addition of Pro-Ca can promote the shoot growth of rice seedlings under salt stress, improve root vigor, enhance activity of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) and ascorbate peroxidase(APX), increase the content of soluble protein and proline, reduce the relative conductivity of leaves and the production rate of O·2-, increase the SPAD of leaves and increase the net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Tr), intercellular CO2 concentration(Ci) and apparent mesophyll conductance(AMC). Comprehensive analysis showed that treatment with 100 mg·L^(-1) Pro-Ca had the best effect, which showed that the stem base width, total root length, biomass accumulation, Pn and CAT had a maximum value. It is preliminarily inferred that under salt stress, Pro-Ca reduces seedling O·2-production rate and electrolyte penetration by increasing plant antioxidant enzyme activity, chlorophyll content and osmotic adjustment substance content, thereby protecting the integrity of the cell structure, promoting seedling growth and the increase in photosynthetic rate, so as to enhance the salt tolerance of rice seedlings.