Studies on the absorption of nutrient elements in muskmelon. IV

Abstract

1. The aim of the present study is to find out some relation between nutritional accumulation and growth of muskmelon (var. Earl's Favourite) grown under the experimental condition reported in the previous papers. The design of fertilizer treatments is presented in Table I. The results obtained are shown in Tables 2 to 8 and in Figures 1 to 6. 2. Plant height increased rapidly during the five weeks after planting, and then remained constant until harvesting time. The greatest increasing Tate in fruit weight was observed between the second and third weeks after pollination when the fruit net appeared, while there was a great increase in soluble solids in fruit during the two weeks before harvesting time. 3. The amounts of nitrogen in whole plant increased up to the ninth week after planting, and then remained constant until harvesting time. The amounts of nitrogen in leaf increased rapidly during the five weeks after planting, and then slowly during the following four weeks, but decreased thereafter until harvesting time. Those in stem were less than those in leaf, while the accumulation processes in stem were analogus to those in leaf. On the other hand, its accumulation in fruit increased linearly throughout the entire growing period. From these results, it was found that a part of nitrogen in leaf and stem translocated from these organs to fruit during the two weeks before harvesting time. 4. The amounts of phosphorus in whole plant increased up to harvesting time. The amounts of phosphorus in leaf at the standard and low levels of nitrogen increased rapidly between the third and fifth weeks after planting, and then increased slowly until harvesting time, while those of the latter increased slowly between the third and seventh weeks after planting, and then remained constant until harvesting time. The accumulation processes in stem were analogus to those in leaf. On the other hand, the accumulation in fruit increased almost linearly throughout the entire growing period. 5. The amounts of potassium in whole plant increased in almost a linear pattern between the third and ninth weeks after planting, and then increased slowly until harvesting time. The amounts of potassium in leaf and stem increased up to the ninth week after planting, and then remained constant until harvesting time. On the other hand, its accumulation in fruit increased almost linearly throughout the entire growing period. 6. The amounts of calcium were greater in leaf than any other organs of plant and the accumulation in leaf showed almost a linear increase throughout the growing period. Moreover, decreased supply of nitrogen to the plant resulted in greater accumulation and percentage of calcium in leaf. 7. The amounts of magnesium were greater in leaf than in any other organs and those at the standard level were greater in leaf than those of other levels throughout the growing period. The amounts of magnesium in leaf increased up to the ninth week after planting, and then increased slowly until harvesting time. Moreover, magnesium accumulation in whole plant were analogus to that in leaf. 8. The accumulation ratios of phosphorus to nitrogen (100) in leaf and whole plant were about 30 to 50 throughout the entire growing period; those of potassium, calcium and magnesium to nitrogen increased rectilinearly up to fruit harvesting time. On the other hand, the highest ratio of all other elements to nitrogen in fruit was observed between the second and third weeks after pollination when the fruit net appeared. 9. The amounts of N, P2O5, K2O, CaO and MgO in whole plant, at the low level which received ammonium sulphate and at the standard level which received rape-seed cake as nitrogen source were as follows. Those of the former were 6.2, 2.6, 18.5, 15.5 and 2.2g; those of the latter were 7.6, 3.1, 20.5, 17.2 and 3.5g per plant.