Effects Of Straw Returning And Nitrogen Management On Soil Urease And Photosynthetic Characteristics And Yield In Wheat

Nitrogen application and straw returning affect winter wheat yield,growth and the activity of soil urease,the proper combination mode of N and straw returning was studied in this exprement.A two factors field experiment in 2016-2017 growing seasons was conducted consecutively in Hebi Academy of Agricultural Sciences,Henan province.Taking Zhou Mai 22 was used as the test material,three straw returning patterns and six different fertilizer applications(0-450kg/hm2)were setted in this experiment.Growth condition,grain quality and crop yield of wheat under different treatments were measured and analyzed respectively.The major results as follows:1.Effects of straw returning and nitrogen fertilizer on soil urease.Compared with no straw returning,the activity of soil urease with straw treatment was significantly increased,respectively,J1(1?2 straw returning)was higher than that of J2(full straw returning).The activity of soil urease with nitrogen fertilizer treatment was higher than that with no nitrogen fertilizer,it rised in advance then fell with the increase of nitrogen rate and reached the highest level under N3(300kg/hm2)treatment.In pre-winter,soil urease activity value was higher than wintering period,began to rise from returning green stage and reached its peak in filling stage,it became stable in mature period.2 Effects of straw returning and nitrogen application on soil total nitrogenSoil total nitrogen increased with the increase of straw returning amount and changed with the growth process moving forward.It rised in advance then fell and reach the highest rate in the heading stage.The effect of six nitrogen mangements on soil total nitrogen had no significant difference,it also rised in advance then fell during its growth stage and maintained steady growth in mature stage.3 Effects of straw returning and nitrogen application on leaf area index and photosynthetic physiological characteristics of wheatNitrogen application can significantly increase the leaf area index of wheat under the same straw returning amount,among which the leaf area index of N2 and N3 is higher,accounted for 30% before winter and more than 70% in jointing period.Straw returning significantly increased the SPAD value of flag leaf of winter wheat and net photosynthetic rate(Pn).J1(1?2 straw returning)was significantly higher than that of J0 and J2 in 8 days,14 days and 20 days after flowering(full straw returning);The value of SPAD and Pn in flag leaf of nitrogen increased with the mangements of nitrogen,among which the value of SPAD and Pn of flag leaf under N3 were the highest in 8 days,14 days,20 days and 26 days after flowering,and reach the lowest under N5(450kg/hm2)treatment,These results showed that excessive nitrogen application can’t benefit photosynthesis.Grain filling rate increased gradually with the increase of nitrogen application rate in the condition of no straw returning,Under the treatment of J1(1?2 straw returning),The grain filling rate under N2 and N3 ware higher than other nitrogen treatments during the whole growth stage,followed by N1> N4> N5> N0.Results showed that proper nitrogen application(N2 and N3)could improve grain filling rate.4 Effects of straw returning and nitrogen application on quality and yield of wheatThe protein content and wet gluten value of wheat grain increased with the increase of nitrogen application rate in the condition of J0;Under the condition of J1(1?2 straw returning)and J2(full straw return),grain protein content of winter wheat and gluten values were the highest in N3 and N4 respectively.With the increase of nitrogen application rate,the grain yield of wheat increased under J0 treatment;Under the condition of J1(1?2 straw returning),the yield of N3(300kg/hm2)reached 9919.34 kg/hm2,which was significantly higher than other treatments;Under the condition of J2(full straw return),the yield level of N2(225 kg/hm2)was was 9149.39kg/hm2,which was higher than the other treatments.The above results showed that staw returning with a moderate amount of nitrogen application(225kg/hm2-300kg/hm2)could improve grain yield,excessive nitrogen application not only wastes resources,increases production costs,but also decreases production.