Fertilization Strategy Of Wheat Based On Ratio Of Ecological Stoichiometry Of Nitrogen And Phosphorus

In this paper, two kinds of potted strong gluten wheat(Zhenmai 168) and weak gluten wheat(Yangmai 15) were selected as experimental objects, different gradients of nutrient N/P ratio were established by fertilizing of various amount of nitrogen and phosphorus. The ecological stoichiometric rule of C/N/P, photosynthetic traits,quantitative variation of rhizospheric microorganism and uptake characteristics of nutrients for the flag leaf of wheat under different gradients of nutrient N/P ratio were studied in detail. The results can supply theoretical and technical assistance for the optimization of fertilize application. This research mainly draw the following conclusions:(1) Under the certain concentrations of N and P in soil, the content of N of wheat leaf in jointing stage increased first and decreased afterwards with the increasing of nitrogen in soil, while the content of N in booting and postulation stage were increased straightly with the increasing of nitrogen in soil. The content of P of wheat leaf in all of the three stages were increased straightly with the increasing of phosphorus in soil. At the same time, the content of C was stable during the growth of wheat.(2) Under the certain concentrations of N and P in soil, the N/P ratio in leaf was significantly positively correlated to the N/P ratio in soil(P<0.05). The content of N/P of wheat leaf in all of the three stages were increased straightly with the increasing of N/P ratio in soil, and the increase amplitude was higher in jointing stage than the rest two stages, while the increasing of N/P ratio in postulation stage was less obvious.The C/N ratio in leaf was negatively correlated to the N/P ratio in soil(P<0.05), the content of C/N of wheat leaf in reproductive periods were decreased straightly with the increasing of N/P ratio in soil, and the decrease amplitude follows the order of filling stage > jointing stage > booting stage. The C/P ratio in leaf was significantly negatively correlated to the concentration of P in soil(P<0.05), the ratio of C/P of wheat leaf during reproductive periods were decreased with the increasing of P in soil,and the decrease amplitude follows the order of jointing stage > booting stage >filling stage.(3) Under the certain concentrations of N and P in soil, the chlorophyll content of the wheat leaves increased with an increase of soil available N and P. When soil available N was less than 258.4 mg/kg, photosynthesis(Pn) exhibited a continuously increasing trend with decline of soil N/P. But, when soil available N reached at 308.4mg/kg, photosynthesis(Pn) first increased and then decreased with decline of soil N/P.Among the treatments with the same level of available N, the F0, Fm, qP, and ΦPSII values increased, while the NPQ decreased with the decline of soil N/P. While, among the treatments with the same level of available P, F0 initially increased and then subsequently stabilized. Meanwhile, Fm, qP, and ΦPSII initially increased before decreasing, NPQ initially decreased before increasing with the increase of soil N/P. So,under the experimental condition, the Pn and ΦPSII of Zhenmai168 and Yangmai15 reached highest level when the soil N/P was 2.88.(4) Under the certain concentrations of N and P in soil, The quantity of aerobic bacteria, actinomyces, and fungus in rhizosphere soil were significantly negatively correlated to N/P ratio in soil(P<0.05). The increasing of phosphorus in soil resulted in the numercial improvement of aerobic bacteria, actinomyces, and fungus in rhizosphere soil, which increased first and decreased afterwards with the increasing of nitrogen in soil, and both of the parameters reached to the highest level with N2P3 treatment. The number of aerobic bacteria, actinomyces, and fungus in rhizosphere soil that fertilized differently follow the order of aerobic bacteria > actinomyces >fungus.(5) Under the certain concentrations of N and P in soil, the application of N and P significantly increased grain yield, and the highest yield was found under the joint application of N, P fertilizer(P<0.05). The application of N and P fertilizer increased total nutrient accumulation and nutrient absorption per 100-kg seeds, but reduced nutrient dry matter production efficiency and nutrient grain production efficiency(P<0.05). Meanwhile, fertilizer recovery efficiency, agronomic efficiency and physiological efficiency always declined with the increasing N and P application rate.