Seedling Emergence and Mesocotyl Elongation as affected by Temperature and Seeding Depth in Direct-seeded Rice on Dry Soil

벼 건답직파재배에서 온도 및 파종심도가 종자의 출아와 중배축 신장에 미치는 영향

Climatic condition and seeding depth affect the seedling stand and early growth in the direct-seeded rice cultivation on dry soil. This experiment was conducted to elucidate the effects of the day /night temperatures and the seeding depths on the seedling emergence and mesocotyl elongation of rice seed. Three combinations of the day/night temperatures(25/2$0^{\circ}C$ 20/15$^{\circ}C$ and 20/1$0^{\circ}C$) were employed with seeding depths 1, 3, 5 and 7cm at the Phytotron of the Crop Experiment Station in 1991. It appeared that seedling emergence ratio increased and days to seedling emergence decreased in the high temperature (25/2$0^{\circ}C$) and the deep seeding depth (5 and 7cm) condition. The seedling emergence ratio did not. show the, difference up . to the seeding depths of 3cm and below, but the ratio decreased from the seeding depths of 5cm and above. Plant height and leaf number were almost the same up to the depths of 3cm at 30 days after seeding, but those of the seeding depths of 5cm and 7cm were remarkably reduced in all temperature combinations. Mesocotyl and lower internode elongation were seen in the high temperature(25/2$0^{\circ}C$) with the seeding depths of 5cm and 7cm. In the seeding depth of 6cm, of the tested varieties, Tamjinbyeo and Odaebyeo showed the highest emergence ratio. Generally, leaves of all tested varieties appeared approximately in the soil depth of 3cm, so the reasonable seeding depth will be around 3cm in the direct-seeded cultivation on dry soil.

벼 건답직파재배에서 온도와 파종심도를 달리 하여 벼 품종의 출아와 중배축 신장을 조사한 결과를 요약하면 다음과 같다. 1. 온도가 높고 파종심도가 얕을수록 출아율이 높았으며 출아소요기간이 짧았다. 2. 각 처리온도 별로 파종심도 3cm이하에서는 출아율이 큰 차이가 없었으나 5cm이상이 되면 현저히 낮아졌다. 3. 파종 30일 후의 초장과 엽수는 온도가 낮을수록 감소하였고 파종심도가 5cm 이상이 되면 생육이 현저히 저하하였다. 4. 온도가 높고 파종심도가 5cm 이상일 때는 중배축과 하위절간의 신장이 컸다. 5. 파종심도 6cm에서 벼 품종들 중 출아율이 높았고 품종은 오수벼, 탐진벼이었고 중배축의 신장은 품종간 차이가 현저하여 5～16mm의 분포를 나타내었으며 제 1본엽의 출현이 지중 3～4cm에 이루어져서 파종심도는 지중 3～4cm가 적당한 것으로 판단되었다.