| This experiment conducted in the water and fertilizer coupling research experimental station of Shandong agricultural university.Two different irrigation amount level after anthesis:normal irrigation by 450 mm(Wl)and decrement irrigation by 325mm(W2).Three different kinds of ditch-buried organic matter return:no straw returned(MO),wheat straw returned(Ml),mixtures of cow manure and wheat straw returned(M2).Increase decrement irrigation by 400 mm(W3)in 2017.Through the combination of different irrigation amount and returning organic matter after anthesis,we analyzed the change of soil moisture and nutrient after anthesis,water use efficiency,and the dynamic changes of the accumulation of dry matter distribution,also revealed the changes of the photosynthetic rate and chlorophyll fluorescence of the summer com laws,discussed the optimal of returning organic matter and post-anthesis supplemental irrigation,fertilization management measures.In order to reasonable irrigation fertilization,retention of fat to give full play to the corn after water use efficiency,photosynthetic potential and provide a scientific basis for crop production.The main results were as follows:1.The effect of returning ditch buried organic matter and post-anthesis supplemental irrigation on soil carbon and water environmentThe soil moisture changes mainly showed in 0-60 cm soil layer after irrigation during after flower.The maximum difference between the soil moisture content between the same deal were found in the 0-10 cm soil layer,but the difference decreases with the increase of soil depth.The soil water content difference in all treatments increases gradually as the soil layer deepen,and reached the maximum in straw landfill.In 2016,volume average water content in 30-40 cm soil layer of W1M1 and W1M2 were 1.2%and 2.6%higher than W1M0 processing respectively.In 2017,compared with W2M0 and W3M0,soil water content in 20-30 cm soil layer of W1M2 increased 8.4%and 4.6%respectively in flowering to full ripeness period.Normal irrigation mixed with cow dung straw counters-field combination can effectively keep the soil moisture content,enhance the top layer of soil water storage capacity,improve maize growth and development.The organic carbon content of organic matter returned to the field showed an overall upward trend,and the increase and growth rate of organic carbon in W1M2 was greater than W1M1.Compared with W2M2,W1M2 respire at a higher increase rate with the soil organic carbon in each soil layer in the early stage of the growth,and respire at a higher decrease rate in the later stage.Soil microbial biomass carbon reached its maximum at the anthesis stage.Under the condition of returning the same organic matter,Soil microbial biomass carbon is shown as W1>W3>W2.Under the condition of the same moisture,microbial biomass carbon content of M2 was significantly higher than that of M1 and MO.Soil respiration rate of each treatments in maize field were generally falling as the corn growth period.In 2017,compared with W2M2,soil respiration rate of W1M2 were increased 21.4%,23.8%,24.4%,21.4%and 32.6%in each growth period after flower.The combination of normal irrigation and cow manure straw returning effectively improves the soil environment.2.The effect of returning ditch buried organic matter and post-anthesis supplemental irrigation on photosynthetic characteristics and chlorophyll fluorescence characteristicsA two-year data study showed that Pn?Gs and Tr of differently treated summer maize ears showed a unimodal trend with the prolongation of the post-anthesis time,peaked at the grain-filling stage,and the change trend of Ci and Pn was opposite.Under the same moisture condition,compared with W1M1,the Pn of W1M2 increased by 7.4%at an average of two years after anthesis,and the average Gs increased by 13.0%,the average Tr increased by 15.5%,and the average Ci decreased by 8.6%.When the same organic matter was returned to the field,W1 could significantly increase the Pn of maize compared to W2 at the post-anthesis stage,and it was significantly different with the prolongation of the post-anthesis time.There was no significant difference in Pn between W1 and W3 post-anthesis.Compared with W2M2,the Pn of W1M2 increased by an average of 15.7%for two years,the average Gs of W1M2 and W3M2 increased by 18.9%and 9.6%,the Tr increased by an average of 20.0%and 24.4%,and the Ci decreased by an average of 12.8%and 6.2%.The combination of normal irrigation and return of cow manure straw to the field increased the net photosynthetic rate,stomatal conductance,and transpiration rate of post-anthesis leaves,reduced the intercellular CO2 concentration,and maintained the photosynthetic performance of post-anthesis leaves at a high level.With the advancement of the post-corn flowering period,the SPAD values of the post-anthesis maize leaves showed a decreasing trend,and the SPAD value of each treatment gradually decreased with the difference of the fertility period.Compared with W2M2,the SPAD value of W1M2 and W3M2 increased by 2.9%and 1.7%respectively after the anthesis stage.Compared with W1M0 the SPAD value of W1M1 and W1M2 was increased by 2.1%and 3.4%.When the same organic matter was returned to the field,Vj and Wk appeared to be W2>W3>W1 after anthesis.Compared with W2M2,Vj and Wk of W1M2 and W3M2 decreased by 4.0%,3.8%,4.1%,and 1.4%on average.Under the same moisture condition,Vj and Wk were expressed as M0>M1>M2.The ?po,?o,?EO and PIABS of photosystem ?(PSII)of maize leaves after different flowering treatments showed a unimodal trend with the prolongation of the post-anthesis time and peaked at the grain-filling stage.The ?po,?oand?EO of the W1M2 treatment were superior to other treatments,but there was no significant difference between the treatments.The difference in PIABS between treatments was significant.Compared with W2M2 and W3M2,the PIABS of W1M2 treatment increased by an average of 14.7%and 18.1%.Compared with W1M1,the PIABS of W1M2 increased by an average of 10.2%in two years after anthesis.The combination of normal irrigation and cow manure straw returning can reduce the senescence of post-anthesis maize leaves,increase the absorption and transmission of PSII light energy after flowering,and make the leaves maintain a higher utilization rate of light energy.3.The effect of returning ditch buried organic matter and post-anthesis supplemental irrigation on yield formation and water use efficiencyThe combination of normal irrigation and cow manure straw combined to return more conducive to the growth of corn dry matter,improve the accumulation of dry matter after corn flowering and transport capacity to promote the accumulation of dry matter quality.Under the same organic matter returned to the field,the W1 treatment can significantly improve the grain yield of maize.W1M2 increased by 14.9%and 15.3%respectively over the two years of W2M2.Under the same moisture condition,the grain yield of maize can be increased by the return of organic matter,and the specific expression is M2>M1>M0.Normal irrigation,and the combination of cow manure straw and straw mulching can significantly improve grain number,1000-grain weight and single grain weight.However,under the condition of water-saving irrigation,the effect of increasing yield of organic matter in the field,especially in the mixed field of cow manure,was significantly higher than that of normal irrigation.Under the same moisture condition,the change trends of water use efficiency,irrigation water use efficiency and yield were consistent,showing that M2>M1>M0.The water use efficiency and irrigation water use efficiency of W1 M2 over W1 M1 and W1 M0 increased by 3.5%,3.5%,4.6%,and 5.4%on average for two years.When the same organic matter was returned to the field,W2>W3>W1 was observed for water use efficiency and irrigation water use efficiency.Compared with W1M2,W3M2 water use efficiency and irrigation water use efficiency increased by 6.2%and 6.7%,respectively.The results showed that the yield of W1 treatment was significantly higher than that of W2 treatment,but with the decrease of irrigation water,the water use efficiency gradually increased.W2 treatment significantly increased the water use efficiency and the irrigation water use efficiency,the water use efficiency and irrigation water use efficiency of the mixed return of cow manure and straw is better than straw and field return.4.The distribution characteristics of soil,maize plant and canopy gas 13C and 15N in the soil under the ditch-buried straw return.Discovery by isotope tracer technology,The value and carbon content of the maize vegetative organs were highest at 80-120 cm.The carbon content of grain is greater than that of the vegetative organ.Corn stems of 15N abundance value and nitrogen content with the increase of the height of gradually diminishing,15N abundance value of the leaf and show the opposite trend,leaf in 80-12 cm height to obtain the highest nitrogen content,and the nitrogen content of vegetative organs of leaf>stem>sheath.In the maize fruit part,the value of the?13C maize fruit part of grain>spline>cob>husk,with the maximum carbon content of the cob and no significant difference in other parts.There was no significant difference in the 15N abundance value of the maize fruit part,Grain has the highest nitrogen content.In the anthesis stage,the soil 15N abundance value of the 20-40 cm straw filling layer was significantly higher than that in the 0-20cm soil layer.In the full ripe stage,the 15N abundance value,Ndff value and Ndff(%)were opposite to the anthesis stage.It was found that the total variation trend of the total change of the ?13C and CO2 concentration in the full ripe stage and the filling stage was basically the same.The ?13C can firstly increase and then decrease with the increasing of the height of maize canopy in different treatments,the C02 concentration is the opposite.The CO2 concentration of the full ripe stage of the canopy was significantly higher than that of the grouting period,the ?13C is the opposite. |
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