Changes of Principal Components in the Sweet-Potato Plants in the Growing Period

Abstract

In order to make clear the basic principles of high yield of sweet potato, variety Norin No. 10 was planted for this experiment in the year of 1953, in which, the increase or decrease of essential components, in the different organs, during their growing period have also been carefuly dtudied. The reaults obtained are as follows: 1. N or K2O percentage in the leaf-blade reach to the maximum, in the middle of July respectively and during this period, the formation of tuberous root is also observed with naked eye. 2. Immediately after the N amount in the leaf-blade or K2O amount in the petiole attains the maximum, that is, after Aug. 20, and at that time starch in the tuber increases very rapidly. This period is the leading thickening stage of tuberous root. 3. The starch percentage in leaf-blade becomes constant after July 11, so that it is presumed that assimilated stach is transfered directly to the tuber without being stored in the aerial part of plant body like other crops. 4. In order to make survey on the growth of tuberous root, it will be appropriate to investigate the maximum percentage of N and K2O in leaf-blade, and also maximum amount of N in leaf-blade and K2O in petiole with reference to various environmental conditions. 5. Some portions of components in the tuberous root are presumed to be transfered from the aerial parts of plant body after a short stay. Their proportions are as follows: [table]