Effects of soil nitrogen and phosphorus contents on ecological stoichiometry of wheat leaf

Ecological stoichiometry is a science that studies the balance of energy and multiple chemical elements in the ecosystem. The contents of C, N and P and the related ecological stoichiometric ratios (N:P, C:N and C:P) in plants can be used to judge the level of nutrient supply during plant growth period. In this paper, a technical guidance for precise fertilization in wheat production was provided by determining the response of ecological stoichiometry of major elements in wheat leaf to different soil nitrogen and phosphorus conditions. The weak gluten wheat variety 'Yangmai 15' and strong gluten wheat variety 'Zhenmai 168' that were widely cultivated in the study area were selected as test materials. Using pot experiment, 16 treatments of different nitrogen and phosphorus gradients were set up and the ecological stoichiometric ratios of N:P, C:N and C:P at jointing, booting and grain-filling stages analyzed for different treatments. The results showed that:1) at jointing and booting stages, when soil N:P was 7.04-8.73, N:P of the two wheat varieties leaves were higher. At grain-filling stage when soil N:P was 8.73-10.42, N:P of the two wheat varieties was higher. There was significant positive correlation between N:P in wheat leaf and N:P in soil, but the correlation became weaker with wheat growth. 2) At a low soil N level (108.4 mg·kg^-1), leaf C:N of the two wheat varieties was at a higher level. There was a significant negative correlation between C:N in wheat leaf and N:P in soil indicating that C:N in wheat leaf decreased with increasing of N:P in soil. 3) At low soil P level (29.6 mg·kg^-1), C:P of the two wheat varieties leaves were higher as well. There was extremely significant negative correlation between C:P in wheat leaf and P content of soil, which suggested that C:P in wheat leaf decreased with increasing soil P content. The above results indicated that different supply levels of N and P in soil significantly changed leaf ecological stoichiometric ratios of different wheat varieties. Therefore, the steady-state characteristics of ecological stoichiometric ratio can be used as an important reference indicator for nutrient regulation in wheat production.