Variation in Grain Quality and Yield of Black-colored Rice Affected by the Transplanting Time and Temperature during Ripening Stage

흑미 품종의 이앙기와 등숙기 온도 변화에 따른 품질 및 수량 변화 특성 구명

Abstract

Black-colored rice contains anthocyanin, which has an antioxidant function on the seed coat. Anthocyanin content is greatly affected by the cultivation environment, especially the average temperature during the ripening stage. Generally, low temperatures during the ripening stage increase anthocyanin content. To control the average temperature during ripening stage in the field, transplanting time has to be regulated. In this study, anthocyanin content variation was examined in relation to the transplanting time and the average temperature during the ripening stage. For the study, fourteen black-colored rice cultivars with different maturity types (four of early-maturing, five of medium-maturing, and five of medium-late maturing) were selected. The transplanting times used were May 20, June 5, June 20, and June 30. The field experiment was conducted in the Miryang, Kyoungsangnamdo province, Korea from 2014 to 2017. The anthocyanin content in all cultivars was higher when the transplanting time was delayed, and the highest anthocyanin content was observed in the transplanting on June 30. Variation in anthocyanin content according to the change in transplanting time is the greatest in the early maturing cultivars. The least change was observed in medium maturing cultivars. Regression analysis showed a significant correlation between temperature and anthocyanin content, but the degree of correlation was very low in the medium maturing cultivar. As a result, the optimal average temperature during the grain filling stage for increasing the anthocyanin content of black colored rice was $22{\sim}23^{\circ}C$. The rice yield increased in plants transplanted until June 20 and decreased thereafter owing to low temperature during the grain filling stage. The anthocyanin content increased with delaying the transplanting time up to June 30 but the rice yield decreased after June 20. Nevertheless, the rate of increase in anthocyanin content was higher than the rate of decrease in rice yield. As a result, the optimum transplanting time and an average temperature of grain filling stage for black-colored rice variety were June 30 and $23{\sim}24^{\circ}C$ considering both anthocyanin content and rice yield.

본 실험은 흑미 품종14종을 이용하여 남부지방에서 현미수량과 안토시아닌 함량을 동시에 고려한 적정 이앙시기 및 등숙온도(출수 후 30일간 평균온도)를 구명하기 위해 2014년~2017년 까지 4년간 밀양에서 실시하였다. 1. 최대 현미수량을 얻기 위한 흑미의 적정 이앙시기는 조생종의 경우 6월 20일, 중생종과 중만생종의 경우 6월 5일~6월 20일 사이였으며 적정 등숙온도는 $24{\sim}26^{\circ}C$였다. 2. 흑미의 기능성 성분인 안토시아닌은 이앙시기가 늦어짐에 따라 그 함량이 증가하여 모든 흑미 품종에서 6월 30일에 이앙하였을 때 가장 높았으며 안토시아닌 함량이 높은 고품질 흑미 생산을 위한 적정 등숙온도는 $22{\sim}23^{\circ}C$였다. 3. 현미수량과 안토시아닌 함량을 동시에 고려한 안토시아닌 생산량은 이앙기 6월 30일, 등숙온도 $22{\sim}23^{\circ}C$에서 가장 높았다.

Fig. 1. Variation in anthocyanin content with change in transplanting time in black-colored rice cultivars. Values with the same letters in a column are not significantly different at the 5% level as determined using DMRT.

Fig. 2. Correlation analysis between anthocyanin content and average temperature for 30 days after heading in blackcolored rice.

Fig. 3. Variation in anthocyanin production with changes in transplanting time in black-colored rice cultivars. Values with the same letters in a column are not significantly different at the 5% level as determined using DMRT.

Table 1. Average temperature for 30 days after heading of black-colored rice cultivars.

Table 2. Heading date, yield, anthocyanin content, and anthocyanin production of early maturing black-colored rice cultivars with different transplanting times.

Table 3. Heading date, yield, anthocyanin content, and anthocyanin production of medium maturing black-colored rice cultivars with different transplanting times.

Table 4. Heading date, yield, anthocyanin content, and anthocyanin production of medium-late maturing black-colored rice cultivars with different transplanting times.