嶺南地域 乾畓直播裁培適應 벼 品種選定

Screening for adaptability of Korean rice cultivars to direct seeding on dry soil in southeastern plain

This experiment was conducted to screen the adaptability of Korean rice cultivars to direct seeding on dry soil at Yeongnam Crop Experiment Station in 1992. Twelve rice cultivars, two of early maturity. four of medium maturity and six of medium-late maturity, were seeded from May 1 to June 20 with ten-day interval. Based on the minimum cumulative temperature for ripening, 760℃ for forty days after rice heading, the critical late seeding date were June 20 for early maturity varieties, June 10 for medium maturity ones, and May 30 for medium-late maturity ones. Especially, the critical late seeding date for Tamjiribyeo, a medium-late maturity rice cultivar, was May 20. Changes in agronomic characters by direct seeding as compared with transplanting should be checked on the basis of seeding date rather than transplanting date. There are no problems in germinability at fifteen days after seeding except Sangjubyeo, Hwaseongbyeo, although varietal difference of low temperature(15℃) germinability was clearly recognized at ten days after seeding. Degree of seedling emergence(1~9) at twenty days after May 1 seeding under the field condition was good in Dongjinbyeo, Yeongnambyeo, Tamjinbyeo, and Donghaebyeo, but it was relatively fair in Jinmibyeo, Hwaseongbyeo, and Ilpumbyeo. Seedling vigor at thirty five days after May 1 seeding also was very vigorous in Dongjinbyeo, but it was normal in Ilpumbyeo. Incidence degree of lodging in the field was more severe in direct seeding than in transplanting. Donghaebyyeo, Yeongnambyeo and Ilpumbyeo were evaluated as lodging tolerant cultivars. Significant negative correlation coefficient between field lodging and breaking strength was recognized regardless of cultivation method. Milled rice yield by direct seeding was nearly 94.8% level of that by transplanting at the same seeding time of May 10. The critical late seeding time of direct-seeded cultivation based on heading date can be explained by the relationship between the seeding time and grain yield. Donghaebyeo, Yeongnambyeo, Ilpumbyeo, Dongjinbyeo, and Tamjinbyeo were recognized as considerably adaptable rice cultivars to direct-seeded cultivation in southeastern plain area by the lodging tolerance and relative level of grain yield compared with transplanting.