0023-6152

AA00697606

24050

Unrefereed

0023-6152

AA00697606

Poor seed germination and uneven early growth are often observed in rice varieties when the seeds have been directly sown into the flooded paddy field. The uniform germination followed by the vigorous early growth is regarded as an essential character for the rice genotypes having a high and stable productivity in the direct sowing cultivation system. In this research we examined the characteristics in germination and early growth of 17 varieties of 0. sativa and 0. glabewima under the deoxidized water condition. Oxygen in water was removed by sodium dithionite. The germination ratio of 0. glaberrima was strongly restricted in the deoxidized water, while the restriction on 0. sativa was not so strict. There was little difference in germination ratio among the varieties of 0. sativa tested in the deoxidized water, but a large difference was detected for the early growth after germination. In the deoxidized water, the two varieties (Razza and Calrose76) among the 15 varieties of 0. sativa had a continuous growth, while the other 13 varieties had no response in growth after germination. It may be expected that these two varieties have a high enzymatic activity in the anaerobic respiration metabolism to get energy necessary for the initial growth. The responses of germination and early growth of rice varieties to the deoxidization treatment had a good agreement with those determined in the flooded paddy soil. This may prove that the germination test in the deoxidized water is useful for screening the rice genotype suitable to the direct sowing cultivation.