Abstract
In western Shizuoka Prefecture greenhouse-grown muskmelons often develop yellow leaf chlorosis, interveinal necrosis and brownish spots on the stems, petioles and veins. Symptoms frequently occur after the application of“minelite”to soil beds or after steam sterilization of greenhouse soils. To identify the cause of this disorder analyses were made on plant tissues and soil samples taken from greenhouses where injured plants were found and from greenhouses where no injured plants were found. With the exception of Mn, there were no significant differences in the levels of macro and main minor elements in leaves of injured or healthy plants. However, MnO concentrations in various parts of plants with typical symptoms were markedly higher than in healthy plants. In addition, available Mn concentrations were markedly higher in soils where injured plants were found than in soils where only healthy plants were found.
An experiment was conducted with a soil having a high level of Mn to determine the effect of steaming at various temperatures on changes in the availability of Mn. Concentrations of available Mn were markedly increased by steaming at high temperature.
The results of this study and the answers received to a questionnaire for growers suggest that the growth injury described here is caused by Mn excess brought about by the application of certain Mn containing fertilizers.
