Abstract
The experiment was carried out in order to investigate the effect of fumigation with sulfur dioxide for a long time on grain production of rice plants. Rice plants were fumigated for 10 days at reduction division stage and flowering stage, respectively. The effect of fumigation was examined as to the yield constitutional components, the percentage of germination and the sulfur content in the kernels and leaves. The results obtained were as follows: 1) When rice plant was fumigated with sulfur dioxide in reduction division stage, number of spikelets per panicle and weight of 1, 000 kernels were decreased with increase of SO2 concentration to which the plants were exposed. There were significant effects at concentration of SO2-0.5 and 5 ppm on percentage of ripened grains. 2) When fumigated in the flowering stage, percentage of ripened grains was decreased to some extent with increase of SO2 concentration. Number of panicles per plant decreased slightly. However, the other components were not affected by treatment. 3) In most plot, percentage of germination of seed gained from plant fumigated by SO2 was not affected by treatment. But in the plot fumigated by 5 ppm SO2 at flowering stage, it decreased by 92%, and seminal root of seedling was somewhat translucent. 4) Content of sulfur accumulated in leaves was increased in proportion to exposed SO2 concentration, although that of kernels was not influenced by treatment. These results obtained in this experiment indicate that the sulfur accumulated in leaves were not translocated to kernels.
