Several Experiments on Improvement of Cultural Technics in Ceylon

[摘要] The author had engaged in research work of rice in Ceylon as a Colombo plan expert in 1961. The results of main experiments conducted by him are summarized as follows. 1. Pot experiment on nitrogen split application (table 1) Growth of rice was divided into five stages and nitrogen was applied as shown in table 1. Compared with nitrogen supply at all growth stages, number of spikelets was most decreased by nitrogen deficit at tillering stage and both number of spikelets and percentage of ripened grains were markedly decreased by that at primordia initiation stage. Consequently grain weight was most decreased in the latter. In case of nitrogen supply at one growth stage, an inverse relation to the above was observed, that is, increase of grain weight was brought about by nitrogen supply at primordia initiation stage. When nitrogen was top-dressed at two stages, the effect on grain weight was the highest in nitrogen supply at primordia initiation stage and reduction division stage. 2. Pot experiment on drainage and percolation of water (table 2 and 3) High rot activity, caused by suppression of soil reduction, and poor tillering were observed in drainage and percolation plot. However, grain weight was not affected by suppression of tillering. Percolation was characterized by high percentage of ripened grains. Re-use of percolated water showed less value of each yield component than no re-use of one. 3. Field experiment on drainage and ridging (table 4) For the purpose of suppressing soil reduction in paddy land of Low-country, drainage and ridging were examined. Drainage showed high yield in both Yala and Maha season. However clear effect was not observed in ridging. 4. Field experiment on cultural improvement in Up-country (table 5) Cultural technics in cold district of Japan were applied, because poor yield in Up-country was assumed to be caused by low air and water temperature. Grain yield was increased under low fertilizer level by using upland seedling, but it was not increased under high fertilizer level. Increased application of P2O5 and K2O showed clear response, but effect of compost on yield was not observed. 5. Field experiment on hill arrangement (table 6 and fig. 1) Hill arrangement was varied in series from square to rectangle under the same density by changing distance between rows and between hills. Grain yield was the highest in medium rectangular arrangement (10"×6") in both H-4 and Murungakayan 302 under standard fertilizer level. Under low fertilizer level, howevr, yield was not so different in accordance with hill arrangement.

[学科分类] 农业科学（综合）