Factors Affecting the Yearly Fluctuation in the Culm Length of Rice(Agronomy)

[摘要] Three rice cultivars, Koshihikari, Koshijiwase, and Kinuhikari, were cultivated in a paddy field under similar fertilizer management practices from 1988 to 1994, and factors affecting the yearly fluctuations in the culm lengths of rice were examined. The culm lengths at the ripening stage were positively correlated with the leaf area indexes (LAI) at the neck node differentiation stage (NNDS) in the three cultivars. The longer lengths of culm were explained by the positive correlation between the lengths of lower internodes at ripening stage and LAI at NNDS. The varietal difference in the regression coefficient of culm length to LAI at NNDS was observed; the coefficient of Kinuhikari, which is a short culm variety, was 5.3 cm/LAI, and those of Koshihikari and Koshijiwase were 11.4 and 16.1 cm/LAI, respectively. This suggests that the sensitivity of elongation of lower internodes and culm to high LAI was lower for Kinuhikari than for Koshihikari and Koshijiwase. The SPAD values at NNDS were positively correlated with the calm length. However, the correlation coefficient was lower for Kinuhikari than for Koshihikari and Koshijiwase. The LAT at NNDS showed negative correlation with the amount of precipitation during the month before flooding. These results indicated that the yearly fluctuation of LAT at NNDS was affected by the air-drying effect on ammonification, which caused the yearly fluctuations of culm length to occur.

[学科分类] 农业科学（综合）

[关键词] Air-drying effect on ammonification;稈長;Chlorophyll meter;乾土効果;Culm length;降水量;Internode elongation;水稲;Leaf area index;節間伸長;Lodging;倒伏;Precipitation;葉面積指数;Rice;葉緑素計