Abstract
Muskmelon (Cucumis melo cv. Earl's Favourite) was grown on two kinds of soil bed (Ando sub-soil and alluvial soil) in a plastic house, in order to evaluate the effect of application rate or rice plant and the trial was conducted with four replications. The results obtained are summarized as follows. 1) In the early stage after transplanting, the plant growth on the Ando sub-soil was inferior to that on the alluvial soil, probably due to the shortage of phosphorus supply, but then recovered, resulting in the same degree of growth in the later stage. The compost application brought a good result; that is, the plant growth was generally increased with increasing the application rate in both soils. 2) The fruit weight and appearances estimated with net condition and spherical form were also increased with increasing the application rate in both soils. 3) The contents of total sugar and individual sugars such as glucose, fructose, and sucrose were higher in the fruit juice from the Ando sub-soil than in that from the alluvial soil. In both soils, these sugar contents were increased with increasing the application rate from 0 up to 1.0 kg/plant, but were significantly decreased at that of 2.0 kg/plant, as compared with the less-application rate. 4) The content of citric acid was lower in the fruit juice from the Ando sub-soil than in that from the alluvial soil. However, the decreasing tendency of this acid content with the application rate was observed in both soils. 5) The water-soluble pectin content in the fruit flesh from the alluvial soil was slightly higher than in that from the Ando sub-soil. This content was decreased with increasing the application rate in the former, but increased in the latter. 6) Taste trial indicated that the taste of fruits obtained from the highest application rate of 2.0 kg/plant was clearly inferior to that from the suitable one. This findings might be attributed to the higher sugar content as well as the lower citric acid and pectin content. 7) The phosphorus concentration in the plant tissues at harvesting time was lower in the Ando sub-soil than in the alluvial soil. The phosphorus and potassium concentration seemed to be increased with increasing the application rate. It was clarified, from the above-mentioned results, that the suitable application rate of rice straw compost to produce the high yield and quality of muskmelon was 1.0 kg/plant and Ando sub-soil was able to be used for the same bed soil as alluvial soil which was presently used for the muskmelon cultivation.
