The color of rice leaves can help determine when to apply fertilizers. By analyzing the pigments in rice leaves, researchers found that the main light absorption peaks were at 432nm in the blue region and 662nm in the red region. The ratio of blue to red light absorption was similar across different types of rice, but decreased with more fertilizer. This ratio was also linked to leaf color and chlorophyll content. Chlorophyll was more abundant than carotenoid when the rice plants were flowering, but the opposite was true 30 days later. Different types of rice had varying levels of chlorophyll at different growth stages.