Applying panicle fertilizer at specific stages of rice growth can increase chlorophyll and nitrogen levels in the leaves, leading to higher grain yield. For one type of rice, Koshihikari, the increase in yield is due to more ripened grains, while for another type, Wuxiangjing 9, it's because of more grains per panicle. Applying fertilizer at certain stages also improves its efficiency and productivity in both rice varieties. However, Koshihikari has lower nitrogen use efficiency compared to Wuxiangjing 9.