镉胁迫对两个水稻品种幼苗光合参数、可溶性糖和植株生长的影响

以较耐镉(武育粳3号,WYJ)和镉敏感(汕优63,SY63)的2个不同耐性水稻品种为材料,采用溶液培养试验,研究了镉处理(Cd.1.0和5.0mol/L)对水稻幼苗光合作用、可溶性糖和生长的影响。结果表明,镉胁迫下,水稻幼苗的光合作用显著地受到抑制。与不加镉的对照相比,随镉水平的提高水稻幼苗净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、气孔限制值(Ls)逐步下降,尤其是在Cd.5.0mol/L处理下的植株,下降幅度武育粳3号显著小于汕优63。蒸腾效率(Te)也随镉浓度的增加而降低,但变化与净光合速率等不同,武育粳3号的下降速率要大于汕优63的。加镉处理使2个水稻品种幼苗叶片可溶性糖含量均显著升高,而叶绿素含量仅汕优63在Cd.5.0mol/L处理下与对照差异显著。加镉处理使汕优63根系生长(根长)显著受到抑制,而株高仅在Cd.5.0mol/L时显著降低。武育粳3号生长与对照差异不显著。本研究结果表明,随着镉处理水平的提高,镉对水稻幼苗的毒害作用增加,但是水稻对镉毒害的响应存在明显的基因型差异。

Effect of cadmium on photosynthesis parameters, leaf soluble sugar and plant growth in two rice cultivars

Contamination of the environment with toxic heavy metals due to anthropogenic activities is one of the major global environmental and human health problems.Cadmium severely inhibits plant growth and even causes plant death by disturbing the uptake of nutrients and inhibiting photosynthesis via degradation of chlorophyll.Two rice(Oryza sativa L.) cultivars: Wuyujing No.3,a Cd tolerant cultivar and Shanyou 63,a Cd susceptible cultivar,were grown hydroponically in this study to investigate the effects of Cd applied at realistic levels on photosynthetic parameters,soluble sugar and plant growth.Rice seedlings were grown in nutrient solutions with cadmium applied at the rate of Cd 0,1.0 or 5.0 (μmol/L).The results showed that the photosynthesis of the leaves was significantly inhibited under Cd stress.In comparison with the control,Cd treatment induced a decline in net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),stomatal limitation value(Ls) and transpiration efficiency(Te) in seedlings and this Cd-induced reduction was significantly dose-dependent. Cadmium treatment increased the concentration of soluble sugar significantly in both cultivars but decreased the content of leaf chlorophyll only in the susceptible cultivar at 5.0 Cd μmol/L.Shoot growth(length) was significantly reduced in the susceptible cultivar only at Cd 5.0 μmol/L,but root growth(length) was significantly inhibited at either Cd 1.0 or 5.0 μmol/L.In contrast,shoot and root growth(length) was unaffected in the tolerant cultivar compared to the control.These results suggested that there was significant genotypical difference in rice in response to Cd toxicity.