镉胁迫对不同水稻品种苗期光合特性与生理生化特性的影响

为了研究镉抗性不同的水稻品种对镉胁迫的生理生化响应差异,采用水培法,以对镉胁迫相对敏感的水稻品种28占和对镉胁迫相对耐受的水稻品种黄粤占为材料,研究了0(蒸馏水,对照),0.05,0.10,0.20 mmol/L 4种不同镉胁迫浓度对该2个水稻品种种子萌发幼苗期的生物学性状、光合特性和生理生化指标的影响。结果表明:不同镉胁迫处理浓度下,2个供试水稻品种28占和黄粤占的苗高、根长、幼苗鲜质量与幼苗干质量均随镉胁迫处理浓度的增大而减小,其中28占减小相对较显著;镉胁迫条件下,水稻叶片的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和胞间CO2浓度(Ci)均呈不同程度的下降趋势。耐镉水稻品种黄粤占Pn、Gs、Tr和Ci的下降均低于镉敏感型水稻品种28占;气孔限制百分率(Ls)呈增加趋势,且品种间差异不显著。随着镉胁迫处理浓度的增加,2个供试水稻品种28占和黄粤占的幼苗叶片叶绿素含量呈下降趋势,而MDA含量、SOD、POD和CAT等抗氧化酶的活性均随着镉胁迫处理浓度的升高而增大,且镉胁迫处理下黄粤占的MDA含量与各抗氧化酶活性较对照的相对增加值小于28占。结果表明,水稻品种黄粤占种子萌发幼苗期对镉胁迫具有较好的抗性。

Effect of Cadmium Stress on Photosynthetic Characteristics and Physiological and Biochemical Traits During Seedling Stage of Different Rice Cultivars

In order to study the physiological responses of different cadmium tolerance cultivars to cadmium stress.Sensitive to cadmium rice cultivar 28zhan and resistant to cadmium rice cultivar Huangyuezhan as the materials,with the hydroponics.The effects of 0(distilled water),0.05,0.10 and 0.20 mmol/L four different cadmium concentrations on the biological traits,photosynthetic characteristics as well as physiological indicators of seedlings were studied.The results showed:Under the stress of cadmium,the aboveground length,root length,fresh weight and dry weight of seedlings decreased with the increase of cadmium concentration,of which 28zhan accounted for a relatively significant reduction.The net photosynthetic rate (Pn),stomatal conductance (Gs),transpiration (Tr) and intercellular CO2 concentration (Ci) of rice leaves showed a decreasing trend in different degrees under cadmium stress.The decrease of Pn,Gs,Tr as well as Ci in the cadmium-tolerant rice cultivars was lower than that in the cadmium-sensitive rice cultivars,and the percentage of stomatal limitation (Ls) increased,and the difference was not significant.With the increased of cadmium concentration,the chlorophyll content decreased,the content of MDA and activities of antioxidant enzymes such as SOD,POD and CAT increased.The activity of antioxidant enzymes was not significantly different from that of the control at 0.05 mmol/L Cd treatment, but there was a significant difference of the 0.20 mmol/L Cd treatment and control, and the relatively activity of the enzyme was lower of Huangyuezhan than 28zhan in the stress of cadmium.The comprehensive analysis of Huangyuezhan had good stability to cadmium stress.