温室メロン

This report, as the fourth on studies of nitrogen nutrition for muskmelon, deals with the results of experiment to clarify the influence of increased calcium concentration in nutrient solution upon the growth of melon and the absorption and assimilation of two forms of nitrogen, NH4-N and NO3-N, in the tissue of it. The results obtained are summarized as follows. 1. Calcium deficiency of melon was recognized in four plots, NCa0, ACa0, NCa20 and ACa20. The increased calcium concentration in nutrient solution promoted the growth of melon, but NCa-series was promoted more remarkably in its growth than ACa-series. 2. The melons of ACa300 were, in spite of their maximum growth among the ACa-series, far less in their growth than those of NCa20 which had slightly revealed calcium deficiency. This fact indicates that the growth of ACa-series was remarkably affected by other factors except the calcium concentration in nutrient solution, namely by NH4+. 3. In ACa-series, even when supplied with calcium concentration up to 300 ppm, the base content in total was not more than 0.270e/100g. Furthermore, the content of three calcium fractions, FNaCl, Face, FHCl of ACa-series were lower than those of NCa-series. These facts suggest that the melons of ACa-series absorbed NH4+ and at same time, they could not avoid the influence of it, however high calcium concentration be supplied. 4. In ACa-series, not only the content of water soluble organic nitrogen such as glutamic acid, glutamine and others was high, but also its ratio to total nitrogen was higher than that in NCa-series. Thisfact shows that NH4+ absorbed in the melons of ACa-series caused some troubles in the synthesis from amino acids to protein of these melons. 5. Compared with the melons of NCa-series in normal growth, those of ACa-series were much higher content of reduced sugar, non-reduced sugar and crude starch. This fact suggests that the carbon and nitrogen metabolism in ACa-series could not be carried out normally and both energy and carbon skeleton were used to counteract NH4+. From the above results, it is concluded that the restricted growth of melons of ACa-series may be due to the use of NH4-N as a sole nitrogen source. The retardation of growth of melons fed with NH4+ may in some degree be improved with the high concentration of calcium, however, the retardation remains just as it was not recovered completely as the case in P and K.