Seed Gravity, Germination, and Optimum Seeding Rate for Machine Transplanting in Colored Rice Varieties

Abstract

최근 소비자들의 건강에 대한 관심이 증가함에 따라 건강기능성 성분이 다량 함유 되어 있는 유색벼 품종의 안전 육묘를 위한 종자의 발아특성, 적정 침종기간 및 적정 파종량을 구명하기 위한 시험결과는 다음과 같다. 1. 현미색이 흑색인 조생흑찰 및 신명흑찰은 비중이 1.0이하의 물에 뜨는 종자가 85.7~86.3%로 대부분을 차지하였고, 비중이 1.06이상 충실한 종자 비율은 1.0~1.3%로 다른 흑미에 비해 상대적으로 낮았다. 한편 신토흑미, 흑진주, 흑설, 흑남, 흑광은 비중이 1.0이하가 15.3~43.7%, 1.0~1.06이 24.6~39.4%, 1.0이상이 25.5~55.7%로 다양한 무게의 종자가 분포해 있었다. 그러나 적미인 홍진주, 적진주, 건강홍미는 일반벼인 일미벼와 같이 충실한 종자인 1.06이상의 비율이 84.0~86.6%로 높았고, 반면 비중이 1.0~1.06은 2.5~4.1%, 비중이 1.0이하의 물에 뜨는 종자의 비율은 9.3~12.1%로 낮았다. 2. 흑미는 일반적으로 물온도에 관계없이 발아율이 적미보다 낮았고 발아속도가 느렸으며 평균발아일수도 길었고 수분흡수율도 낮았다. 그 결과 80%이상 발아하기 까지 침종기간이 적미나 일반벼 보다 2~4일 가량 더 결렸다. 이것은 흑미는 비중이 1.0이하의 가벼운 종자가 적미보다 훨씬 높았기 때문이다. 3. 상자육묘시 흑미의 출아율은 10일묘에서 75.2~82.2%, 30일묘에서 85.3~90.9%로 적미보다 10일묘에서는 4.5~8.0%, 30일묘에서는 0~3.3% 낮았는데 이것은 미출아율 종자가 많았기 때문이었다. 4. 기계이앙 육묘시 유색벼의 안전 육묘를 위한 적정 파종량은 관행 일미벼 어린모 및 중묘의 상자당 성묘개체수를 기준으로 흑미의 경우 어린모는 200~220g, 중묘는 110~130g이었고 적미는 일반벼와 같이 어린모 220g, 중묘 130g이었다. Seeds of colored rice generally have high anthocyanin and flavonoid content but some cultivars have low seed germination rate. This defect poses unstable seedling establishment in nursery bed. The seed gravity variations of 10 colored rice varieties and its effect on germination, seed soaking duration and their optimum seeding rates for seedling raising in machine transplanting were investigated in the experiment. Based on seed gravity distribution of the 7 black- and 3 red-colored rice varieties at three levels of seed gravity (1.0<, 1.0~1.06, 1.06>), the black colored seeds such as Josaengheugchal and Sinmyungheugchal had high amount of specific gravity of below 1.0 ranging from 86~ 96%, while they had only 3~13% of seeds in specific gravity above 1.06. Sintoheugmi, Heugjinju, Heugnam, Heugkwang had various mass of seeds, showing 29~44% for specific gravity of below 1.0, 24~39% for 1.0~1.06 and 25~45% for above 1.06. On the other hand, the red colored rice such as Hongjinju, Jeogjinju and Geonkanghongmi had high percentage of specific gravity of above 1.06 with 84~86% while they had only 9~12% of specific gravity below 1.0 similar to Ilmibyeo of noncolored rice. The black colored seed generally showed low germination percentage, slow germination speed and long mean germination time, and low water absorption rate as compared with seed of the red colored rice which was similar to those of Ilmibyeo used as a control cultivar. The black colored seeds took 2~4 days longer seed soaking duration than the red colored rice before germination. This was related to high seed amount of specific gravity below 1.0 in black colored rices. The high amount of seed gravity above 1.06 in the colored rice seeds was positively correlated with percentage of germination, germination speed and mean germination time, ripened grain ratio and water absorption. Seed gravity distribution effect were less pronounced between back- and red- colored seeds in seedling emergence. The black colored rice has slightly lower normal seedling emergence rate than the red colored rice and Ilmibyeo in the seedbed soil due to high percentage of ungerminated seed. Normal seedling emergence rate of the black colored rice in the seedbed was 75.2~82.2% for 10-day old seedling and 85.3~ 90.9% for 30-day old seedling which was lower by 4.5~ 8.0% and 0~3.3%, respectively, than the red colored rice. Based on the normal seedling number per tray of Ilmibyeo for seeding rate of 10-day and 30-day old seedlings, the recommended seeding rate of black colored rice is 200~ 220g seeds for the 10-day old seedling and 110~130g for the 30-day old seedling in transplanting rice while the seeding rate of the red colored rice was 220g seeds for the 10-day old seedling and 130g for the 30-day old seedling.