カーネーションのマンガン過剰症に関する研究 (第1報)

Abstract

An investigation was made to determine the effects of steam sterilization and pH in soil having a high level of Mn, on the growth and flowering of carnation cvs. ‘Coral’ and ‘Yosooi’. Chemical composition of plant parts and chemical properties of the soil were examined. Treatments were arranged factorially, involving 4 pH levels in the soil (high, medium, low and very low) with sterilized and unsterilized soil.1. In sterilized soil, the number of cut flowers and top fresh weight of both ‘Coral’ and ‘Yosooi’ were decreased at very low pH. In unsterilized soil, those of ‘Yosooi’ were decreased at low and very low pH, and no flowering plants in ‘Coral’ were obtained at low and very low pH. The time of flowering in ‘Yosooi’ was slightly earlier in sterilized soil than that in unsterilized soil. In ‘Coral’, it was markedly retarded in sterilized soil as soil pH was lowered from medium to very low.2. Mn in the various parts of flowering and non-flowering plants of ‘Yosooi’ was significantly increased as soil pH was gradually lowered whether the soil was sterilized or not. Mn in ‘Coral’ showed the same tendency as ‘Yosooi’. Mn content in the leaves of flowering plants of ‘Coral’ was much higher than that of ‘Yosooi’ except those with high pH. The content of N and K, and the ratio of Fe: Mn in the leaves of non-flowering plants of both ‘Coral’ and ‘Yosooi’ were decreased as soil pH was lowered regardless of whether or not the soil was sterilized except for the K content at very low pH. The flowering plants of both ‘Coral’ and ‘Yosooi’ showed the same tendency as the non-flowering plants.3. The intensity of tip burn symptom in the leaves of both ‘Coral’ and ‘Yosooi’ was intensified as soil pH was lowered regardless of whether or not the soil was sterilized. Chlorosis appeared in the young leaves and stems of both ‘Coral’ and ‘Yosooi’ at low and very low pH, and the intensity of chiorosis in ‘Coral’ was much more severe than that in ‘Yosooi’. Mn contents in the leaves and stems of chlorotic plants were much higher than those of normal plants, while N, K, Ca and Fe contents in the leaves of chlorotic plants were much lower than those of normal plants.4. As soil pH was lowered from high to very low, water soluble Mn, NH4-N and Al contents, and E.C. values were increased at the conclusion of the experiment, while easily reducible Mn was decreased. When the soil was sterilized, exchangeable Mn was slightly high, while NH4-N and E.C. values were slightly low.The results of this study suggest that the growth suppression, tip burn symptom in the leaves, and chlorosis in the young leaves and stems of carnation grown in soil having a high level of Mn are highly associated with the excess Mn absorbed by the plant.