环境酸度对紫花苜蓿早期生长和生理的影响

采用沙培的方式研究酸性土壤中土壤酸度对紫花苜蓿生理和生长的影响。结果表明,pH值在5～6的弱酸性环境为苜蓿的最适生长环境,这一酸度范围内幼苗生长正常或受到促进,如单株叶片数高于对照(pH=7)处理23.6%～27.2%、单叶面积高出对照20.87%～25.50%,叶绿素含量高出对照31.2%～27.9%,差异均达显著水平(P<0.05)。而出苗率、株高、根瘤数、根瘤等级、根长和地上、地下生物量亦高于对照;而pH值低于4的环境酸度为低适生长环境,可使苜蓿幼苗受到严重胁迫,出苗率、株高、单叶面积、单株叶片数、根瘤数、根长和地上、地下生物量均低于其他处理。在不同土壤酸度下,质膜透性、叶绿素含量、光化学效率(Fv/Fo)等均存着显著差异(P<0.05),pH＜4的各项生理指标均明显低于pH≥5的处理,其中地上生物量和根系活力分别不足对照处理的55.6%和61.1%(P<0.05)。

Effects of the pH value of an acid environment on early growth and physiology of Medicago sativa W525

The effects of an acid environment in acid soil on seeding growth and physiological index of Medicago sativa were studied by sand culture. The alfalfa grew very well in an acid environment of pH 5 to 6, The numbers of leaves, leaf area, and chlorophyll content per plant were significantly higher (23.6%-27.2%, 20.87%-25.5%, 31.2%-27.9%, respectively ) than those of the control (pH=7). Other morphological features, including rate of germination, height of plant, biomass, number and quality of nodules were not less than in the control (pH=7) and were sometimes increased. Alfalfa growth was seriously restricted when the environmental pH was lower than 4. There was a significant (P<0.05) reduction in the morphological features measured, including rate of germination, height of plant, leaf area, number of leaves per plant, biomass, root length, number and quality of nodules which were significantly (P<0.05) reduced compared with the control group . There were significant (P<0.05) differences in electrolyte leakage, chlorophyll content, Fv/Fo and Fv/Fm under environments with different pH values. All physiological and morphological indexes were significantly (P<0.05) reduced in the weak acid treatment group (pH≥5) compared with the acid treatment group (pH≤4), with above-ground biomass and root activity 55.6% and 61.1% of the control respectively.