Abstract
As a result of examining the influence of the depth of transplanting and earthing up by the difference of the seedling age on the growth and yeild of rice plant with the paper-pot, the following findings have been obtained as a tendency of an entire growth. Regarding the influence of the different time of transplanting, the growth became vary vigorous in the transplanting of twenty-day-old seedlings, especially the number of tillers became large, and the growth were slightly retarded in the transplanting of thirty-day and fourty-day-old seeldings. Further, regarding the influence of the depth of transplanting and erthing up, in comparison with the vary vigorous in shallow transplanting, it was worse in the deep transplanting. It was also observed that the vigorous growth was retarded by the practice of earthing up. As to the influence on yield, the difference due to the different time of transplanting was apparent, that is, the number of non-bearing tillers was large in the transplanting of twenty-day-old seedling in the decline of yield, and on the other hand, it became clear that the transplanting of fourty-dayold seedling as well as the practice of earthing up rose the percentage of bearing tillers and also increased the panicle weight and the number of spikelets resulting in the increase of yield. Seeing from these findings, in the practice of growing seelding by paper-pot, fourty-days-old seedlings in a rice nurcery seem to be pertinent when the fertilizing conditiones are same. It became also clear that shallow transplanting assumed an aspect of direct sowing rice and decrased ultirnately the percentage of bearing tillers and the number of spikelets per panicle, showing a declining tendency of yield. On the other hand, deep transplanting assumed an aspect of upright stading type irrespective of the difference in the seedling age, and kept down the number of non-bearing tillers resultling in the increase of yield by maintaining to a certain extent the numbers of bearing tillers. Pratice of earthing up tn shallow transplanting controls the increase of the number of non-bearing tillers and enhances ripening, and it is effective to prevent the lodging of rice plant as in the practice of deep transplanting. This trend is larger in the transplanting of fourty-day-old seedlings resulting in the increase of yield, but further research seems to be necessary as to the time of earthing up and the degree of deep transplanting.
