The study looked at different types of indica rice to see how they use nitrogen to grow grains. They tested 88 cultivars in 2001 and 122 in 2002. They found that rice with high nitrogen efficiency had lower nitrogen levels in their plants but used it more efficiently. These rice types took in less nitrogen before heading and had high efficiency in using nitrogen for grain production. In conclusion, indica rice with high nitrogen efficiency for grain output takes in less nitrogen, has lower nitrogen levels in plants, and uses nitrogen efficiently.