水稲晩植による減収機構の解析 (要旨) : 〔第3報〕 播種密度を異にした苗の生産能力

抄録

1. In the previous experiment, it was shown that late transplanting results in remarkable decrease of yields. With the aim to analyze th mechanism of such a reduction of yield, the authors compared the growth and yield of rice plants under six different treatments. The seeds were sown at six different densities on nurseries similarly as described in the previous report (2), i. e. the amount of Seeds was 541 cc, 180 cc, 54 cc, 18 cc, 5.4 cc and 2.8 cc per 3.3 m², asrd the seedlings were transplanted individually into six hills per 3.3 m² (90;9×60.6 cm) in g paddy field giving the individual plant a sufficient space for uninterfered growth. 2. The crop from the plant soon densely in the nursery were smaller when transplanted late. On the contrary, the plant sown sparsely seemed to be able to produce higher yield, even by late transplanting. 3. The actual yields of crops given by the seedlings transplanted 30 days later than the standard time were as follows ; (i) Seedlings sown densely gave extremely, low yields. (ii) Seedlings sown 180cc per 3.3 m² gave about an half of th yield by the standard culture. (iii) Sparsely sown plots gave nearly the same or even larger yields compared the standard culture. The reasons for these responses had been discussed in the previous report (1), by the same author. Table : The yielding responses of the rice seedlings grown at different density of stand in the nursery. Seedlings were all transplanted at 30 days later than usual (Variety, Ou-No. 195)