镉对小麦种子萌发及幼苗生理代谢的影响

为研究Cd对小麦种子萌发和幼苗生理代谢过程的影响,以小麦品种绵阳19为材料,用CdCl2.2.5H2O配制4个浓度梯度,测定小麦萌发种子在不同浓度处理下的芽长、根长、维生素C、游离组氨酸及可溶性糖含量。结果表明,Cd处理对小麦种子萌发有强烈的抑制作用,但不同Cd浓度之间差异不显著（P〉0.05）;低浓度Cd（1mg.L-1）处理对小麦幼苗生长有促进作用,而随Cd浓度增加逐渐转变为抑制效应;幼苗根长对Cd的反应较苗长更敏感,低浓度下即表现为抑制效应;随Cd浓度增加,小麦幼苗的维生素C含量由下降转为上升,分别比对照增加-15.5%、11.2%和26.3%;游离组氨酸含量分别比对照增加28.6%、21.7%和15.5%,而可溶性糖含量则随Cd浓度的增加呈现先降后升再降趋势。说明维生素C、组氨酸和可溶性糖含量均可作为小麦幼苗遭受Cd毒害的早期诊断指标,其中维生素C在小麦幼苗抵御Cd毒害过程中可能起关键作用。

Effect of Cadmium on Seed Germination, Seedling Growth and Development of Wheat

In order to clarify the response of wheat cultivar Mianyang 19 to cadmium(Cd) stress, the effects of Cd on seed germination, seedling growth and physiological parameters of contents of vitamin C, free histidine and soluble sugar were studied. The results showed that cadmium significantly inhibited seed germination, but there were no significant differences among different Cd concentrations(P>0.05). Seedling length was promoted under the low Cd concentration(1 mg · L^-1), and then inhibited with the increasing of Cd concentration. Root was more sensitive to Cd than shoot. The content of vitamin C in seedlings increased significantly with the increasing of Cd concentration, being -15.5%, 11.2%and 26.3%of the control. The levels of free histidine in seedlings of treatments increased by 28.6%, 21.7%and 15.5% than of the control, respectively. The content of soluble sugar showed a tendency of decrease at first, then increase, and decrease in the last with increase of Cd concentrations. In conclusion, vitamin C content, histidine level and soluble sugar content could be used as early diagnosis indices for wheat seedling under Cd stress, of which vitamin C perhaps play important role in combating Cd stress.