土壤酸碱度对马缨杜鹃生长和生理指标的影响及适应性评价

Effects of Soil pH on Growth and Physiological Indexes of Rhododendron delavayi and Its Adaptability Evaluation

摘要:

为科学引种、栽培、管理和保护马缨杜鹃，以2年生实生苗为材料，设置土壤pH3、4、5、6、7、8的栽培试验，通过测定22个生长和生理指标，采用主成分分析和隶属函数法进行综合评价。结果表明，除芽长、相对地径增量和落叶数外，其他生长指标均随着土壤pH增加先升高后下降，且pH8处理最小。叶片超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量、可溶性蛋白含量、可溶性糖含量和脯氨酸含量均随着pH增加呈先减少后增加的趋势，SOD、CAT、POD活性和MDA、脯氨酸含量均在pH6处理最低，可溶性糖、可溶性蛋白含量在pH4处理最少。叶绿素a、叶黄素、总叶绿素含量均随土壤pH增大先增加后减少，叶绿素a、总叶绿素含量在pH5处理最多，叶黄素含量在pH7处理最多。净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)均随pH增大先上升后下降，且在pH4~7处理均显著大于pH8处理；胞间CO₂浓度(C_i)在pH8处理最高。主成分分析结果表明，株高增量、气孔导度、蒸腾速率、叶绿素a含量、总叶绿素含量、净光合速率、MDA含量、CAT活性、POD活性和SOD活性等可作为反映马缨杜鹃生长的重要特征指标。基于隶属函数综合评价得出适于马缨杜鹃生长的土壤酸碱度排序为：pH4>pH5>pH3>pH6>pH7>pH8。

Abstract:

In order to scientifically introduce, cultivate, manage, and protect Rhododendron delavayi, 2-year-old R. delavayi seedlings were used as materials in a cultivation experiment with different soil pH levels(3, 4, 5, 6, 7, 8). By measuring 22 growth and physiological indicators, comprehensive evaluation was carried out using principal component analysis and membership function analysis. The results showed that except for bud length, relative ground diameter increment, and defoliation number, all other growth indicators first increased and then decreased with increasing soil pH, reaching the minimum at pH 8 treatment. The activities of superoxide dismutase(SOD), catalase(CAT), peroxidase(POD), as well as the contents of malondialdehyde(MDA), soluble protein, soluble sugar, and proline in leaves all showed a trend of decreasing first and then increasing with increasing pH. The activities of SOD, CAT, POD, and the contents of MDA and proline were the lowest at pH 6 treatment, while the contents of soluble sugar and soluble protein were the lowest at pH 4 treatment. The contents of chlorophyll a, lutein, and total chlorophyll first increased and then decreased with increasing soil pH. The contents of chlorophyll a and total chlorophyll were the highest at pH 5 treatment, while the lutein content was the highest at pH 7 treatment. Net photosynthetic rate(P_n), stomatal conductance(G_s), and transpiration rate(T_r) all first increased and then decreased with increasing pH, and were significantly higher at pH 4 to 7 treatments than at pH 8 treatment; the intercellular CO₂ concentration(C_i) was the highest at pH 8 treatment. Principal component analysis indicated that plant height increment, stomatal conductance, transpiration rate, chlorophyll a content, total chlorophyll content, net photosynthetic rate, MDA content, CAT activity, POD activity, and SOD activity could serve as important characteristic indicators reflecting the growth and physiology of R. delavayi. Based on the membership function method analysis, the comprehensive evaluation ranking of soil pH suitable for the growth of R. delavayi was pH 4 > pH 5 > pH 3 > pH 6 > pH 7 > pH 8.