The researchers studied how different nitrogen sources affect the growth and biochemical properties of rice plants. They tested 15 rice cultivars and analyzed enzymes involved in nitrogen assimilation and photosynthesis, as well as various metabolites like proteins and carbohydrates. They found that adding nitrogen did not increase enzyme activities, but did increase protein content and plant weight. Ammonium supply led to lower plant weight and chlorophyll content compared to nitrate supply. Overall, the type of nitrogen source affected the plant's growth and biochemical composition.