Effects Of Nitrogen Reduction Regulation And Phosphorus Activation On Physiological And Biological Characteristics Of Summer Maize

In order to solve the problems of resource waste and environmental pollution cau sed by excessive application of nitrogen and phosphorus fertilizers in the agricultural p roduction of summer maize,a pot experiment was conducted to study the physiologica l and biological characteristics of summer maize by adding humic acid-acidified bento nite and humic acid urea under the mode of reducing nitrogen fertilizer?common ure a?.On the other hand,the effects of different doses of citric acid,a phosphorus activ ator,on physiological and biological characteristics of summer maize were studied on the basis of normal fertilization.Through the determination and analysis of physiologic al and biological indexes of Summer Maize at different stages,the effects of nitrogen reduction,humic acid acidified bentonite,humic acid urea and citric acid were studied and elaborated in multi-dimension,and the relationship and regularity were clarified in order to provide theoretical support and production guidance for fertilizer reduction an d efficiency enhancement.The results of this study are as follows:?1?Under the same level of nitrogen reduction,the leaf area of the three treatme nts treated with acidified humic acid bentonite and humic acid urea was larger than th at of the common nitrogen fertilizer.For example,at flowering stage?maximum leaf area?,compared with the conventional nitrogen reduction treatment,the leaf area of th e treatment with acidified humic acid bentonite increased by 0.79%⁴.22%,and that o f the treatment with humic acid urea increased by 2.58%⁶.99%.At the same nitroge n reduction level,the addition of acidified humic acid bentonite and humic acid urea significantly increased the net photosynthetic rate,stomatal conductance and transpiratio n rate of leaves at trumpet stage,flowering stage and wax ripening stage,and decreas ed the intercellular CO₂ concentration of leaves,especially the effect of humic acid ur ea.?2?The total dry weight of maize increased by 7.92%³8.37%when acidified hu mic acid bentonite was added in the range of 15%of nitrogen reduction,20.08%⁴5.95%when humic acid urea was used in the range of 15%of nitrogen reduction,2.61%when nitrogen reduction reached 30%,and 2.61%when acidified humic acid urea was added in the same level of nitrogen reduction.Soil moistening and the use of hu mic acid urea can effectively increase the dry weight of leaves,stems,roots,ears,tot al plant weight,leaf area and plant height,and reduce the root-shoot ratio and specifi c leaf area.?3?At the same level of nitrogen loss,the nitrogen uptake of Maize Treated with acidified humic acid bentonite and humic acid urea was higher than that treated with normal nitrogen loss.Compared with the conventional nitrogen reduction treatment,the nitrogen absorption increased by 5.58%¹8.42%in the treatment with acidified humic acid bentonite and 17.42%²8.38%in the treatment with humic acid urea.The ear w eight,grain number and 100-grain weight of Maize Treated with acidified humic acid bentonite and humic acid urea were higher than those treated with common nitrogen f ertilizer.?4?Phosphorus activator citric acid treatment can significantly improve the availab ility of phosphorus in the soil at flowering stage?compared with P0,the degree of ac tivation increased by 11.30%²6.25%?and further promote the absorption of available phosphorus by maize.The chlorophyll content?SPAD?and net photosynthetic rate?P n?of summer maize leaves at different growth stages under citric acid treatment incre ased with the increase of citric acid addition,and reached at flowering stage.The ma ximum value(SPAD 54.37⁵6.07,Pn 38.77³9.90 umol CO₂.m^-2.s^-1);citric acid treatm ent significantly increased dry matter accumulation and maize yield,and citric acid2%was the best addition under different treatment indicators.