マラヤにおける水田温度およびカーボンブラック撒布試験

抄録

These observations were carried out in order to clarify the actual situation of the various temperatures (air, water and soil) in paddy field and to determine the effect of carbon black powder on the temperatures of water and soil, and on the growth of paddy plant, at Bukit Merah Paddy Experimental Station in Northern Malaya. The carbon black powder was dusted on the surface of water in paddy field to decrease the water and soil temperatures by intercepting the penetration of solar radiation into water. Results obtained are as follows:
1. The water and soil temperatures varied according to the growth of paddy plant, but the air temperature at a height of 80cm from soil surface did not seem to be affected by paddy growth. The effect of paddy growth on the water and soil temperatures was negligible up to about two weeks before maximum tillering time, and these temperatures were similar to those before transplanting. Soon after passing that time, the effect of shading of leaves and stems of paddy plants on those temperatures was seen and those temperatures began to decrease gradually, reaching minimum temperatures approximately during heading time and increasing steadily towards harvesting time. Furthermore, the results obtained clearly indicated that the temperatures of water and soil were higher than the optimum temperature on the assumption that the optimum soil temperature for paddy plant is about 27°C, during the growth duration and particularly during the vegetative growth period.
2, The temperatures in carbon black powder plot decreased in both water and soil as compared with control plot, particularly during the period from transplanting to heading. Furthermore, there was no sign of weeds growing in carbon black powder plot. Consequently the growth of plants in carbon black powder plot was excellent as compared with control plot and the yield of grain increased by 24% in comparison.