Effects of Different Nitrogen Levels and Planting Densities on the Quality and Quantity of 'Nunkeunheugchal' Rice

'Nunkeunheugchal' is a waxy black rice variety that has a large embryo. The quality of black rice depends on the anthocyanin content of the rice seed coat, which is mainly determined by cultivation environment. Factors that affect the anthocyanin content include nitrogen level, planting density, transplanting date and harvesting date. This study was carried out to investigate the optimum black rice cultivation conditions by examining the effects of different nitrogen levels and planting densities. An initial study was conducted to determine the optimum nitrogen level in which four levels of nitrogen were applied to the field (0, 4, 8 and 12 kg/10a). As the nitrogen contents were increased up to 8 kg/10a, there was a concomitant increase in rice yields. However, nitrogen levels greater than 8 kg/10a, the yield was maintained at the same level. Correlation analysis indicated that the optimum nitrogen level for maximum yield was 9.6 kg/10a. In addition, anthocyanin levels showed a trend similar to that of yield, with correlation analysis indicating that the optimum nitrogen level for maximum anthocyanin content is 10.6 kg/10a.On the basis of these results, a second study was conducted to determine the optimum combination of planting density and nitrogen level. The planting densities investigated were $30{\times}12$, $30{\times}14$, $30{\times}16$ and nitrogen levels were 7, 9 and 12 kg/10a. A high planting density ($30{\times}12cm$) was shown to produce higher numbers of tillers and yield. As calculated in the first study, a nitrogen level of 9 kg/10a shown to produce the highest anthocyanin content and yield. Collectively, the results of this study indicate that a planting density of $30{\times}12cm$ and a nitrogen level of 9 kg/10a is the optimal combination in terms of maximizing both rice yield and anthocyanin content.

시비량과 재식밀도 변화에 따른 '눈큰흑찰'의 품질 및 수량변화

본 실험은 거대배 흑미 품종인 눈큰흑찰의 효과적인 재배를 위한 적정질소시비량과 적정재식밀도를 구명하고자 2013년~2015년에 밀양에서 실시하였다. 1. 질소시비량이 0 kg/10a에서 8 kg/10a까지 증가하면 주당수수와 수당립수가 증가하여 현미수량이 증가하였지만 8 kg/10a에서 12 kg/10a까지 증가하여도 수량의 변화는 없었다. 회귀분석을 통해 얻어진 눈큰흑찰의 최대현미수량을 위한 적정 질소시비량은 9.6 kg/10a였다. 2. 질소시비량이 0 kg/10a에서 8 kg/10a까지 증가하면 안토시아닌의 함량은 높아졌으나 12 kg/10a까지 처리하였을 때는 오히려 감소하였다. 회귀분석을 통해 얻어진 눈큰흑찰의 최대 안토시아닌 수량을 위한 적정 질소시비량은 10.6 kg/10a였다. 3. 재식밀도가 증가함에 따라 수수는 증가하고 수당립수는 감소하였는데 밀도 증가에 따른 수수의 증가치가 수당립수의 감소치보다 높아 $30{\times}12cm$의 높은 재식밀도에서 가장 높은 수량을 보였다. 4. 질소시비량 7 kg/10a 수준에서는 재식밀도 차이에 따른 안토시아닌 함량의 차이가 없었고 9, 12 kg/10a 수준에서는 밀도가 높아질수록 안토시아닌 함량이 높아져 $30{\times}12cm$ 수준에서 가장 안토시아닌 함량이 높았다. 현미수량과 안토시아닌 함량을 함께 고려한 안토시아닌 생산량은 질소시비량 9 kg/10a, 재식밀도 $30{\times}12cm$에서 69.1 g/10a로 가장 높았다.