Abstract: The effects of different nutrient inputs on photosynthesis and physiologic features in the flag leaves of rice were studied and compared. The results showed that photosynthesis rate (P_n), chlorophll(chl) content and leaves area duration(LAD) were different under different nutrient treatments. Combinded application of chemical fertilizers and organic manure, especially barn yard manure, not only increase P_n, delay discomposition of (chl) in the flag leaves, but also prolong duration of photosynthetic function and light interception in late stages of rice growth. As a result, they bring increase in grain weight and grain yield. In addition, combinded application of organic manure and chemical fertilizers resulted in high P_n of rice leaves, even in high light intensitivity and high temperature at noontime.

Key words: Plutella xylostella, Secondary plant substance, Life table, Interference index of population control