Studies on the Cultural Method of Rice Plants by Sowing Seedlings in Northern Cold District : 1. On the setting up and growth at early stage.

Abstract

1) The influence of seedling-age… Seedlings of different age, ranging from one-leaf stage to five-leaf stage, were tested. Young seedlings with 1∼2 leaves bent upwards earlier, showing less withered leaves, and gave better setting up, which resulted in the higher rate of dry-matter increase at the early stage of growth than the seedlings with 3∼5 leaves. 2) The effect of nutrition… Increased application of phosphorus fertilizer to the nursery bed caused a more active rooting of seedlings after sown and the higher rate of increase of stem elongation and weight of dry matter than the condition without phosphorus fertilizer. An soft and weak elongate seedlings has poorly bent upwards after sown. 3) Time of sowing of seedling… Root development and top growth were very poor when sown under 10°C, an averaged temperature for 10 day period after sowing, as compared to that under 15°C. At the temperature higher than 15°C, such retardation of growth was not observed. 4) Effect of treatment of seedlings… Removal of roots from seedlings prior to their sowing resulted in a delayed growth with poor root development and many withered leaves. Seedlings sown at two-leaf stage under 15°C, an averaged temperature, gave only a few days delay of initial growth as compared to the seedlings transplanted, and it was about the same to the seedlings transplanted after removal of their roots. 5) Roots of seedlings inrush into the soil was observed one day at 15°C, 3 days at 10°C after sown, an averaged temperature. Sowing seedlings on upland field was influenced remarkably by the water contents of soil at the time of setting up. From this experimental results, authors was considered the 2 leaves stage seedlings was high stability on sowing seedlings in northern cold district.