Muskmelons were cultivated in a KUNTAN cultural system using rice hull charcoal, in which we can easily control the nutrient uptake of plants by lowering the concentrations of nutrient, and the effects of controlling the nutrient uptake on the plant growth and the fruit qualities were investigated.
The effects of controlling the nutrient uptake varied with the seasons; remarkable effects were observed on the net formation and its callus development on the fruit surface in autumn, and on the growth of upper leaves in spring, although the weight and size of fruit were not affected. The net appearance was irregular and the callus developed vigorously when the nutrient uptake was not controlled, while the net appearance was uniform and the callus developed moderately when the nutrient uptake was depressed. The excessive growth of upper leaves was reduced by depressing the nutrient uptake. The content of soluble solid seemed to be increased by keeping the nutrient uptake at low level before harvesting.
From these experiments, it is surmised that in order to obtain good quality fruit it will be better to depress the nutrient uptake in fruit enlargement and net initiation stages, to release the depression in net callusing stage and then to remove nutrient elements from culture solution for about 10 days before harvesting in the cultivation of muskmelon in hydroponics.