| The accumulation of dry matter and nutrient absorption and utilization of intercropping maize in winter wheat/spring maize under different N application were studied,and the optimum amount of N applied to improve dry maize accumulation and nutrient absorption and utilization in intercropping maize were explored,which aims to provide a scientific basis for the high-yielding cultivation and the efficient absorption and utilization of N、P nutrition in winter wheat/spring maize in Jin Zhong Basin.In this experiment,four N fertilizer levels were set up in the field split zone design:NO(0 kg · hm-2),N1(150 kg · hm-2),N2(300 kg ·hm-2)and N3(450 kg · hm-2),two planting patterns:spring maize monoculture and winter wheat/spring maize intercropping.The results as follows:(1)Intercropping maize in winter wheat/spring maize system has the advantages of dry matter accumulation,transport and utilization.The dry matter accumulation of monoculture and intercropping maize increased slowly in the early growth period and then increased rapidly to the maximum in mature stage;The dry matter accumulation of intercropping maize at different growth stages was higher than that of monoculture maize at the same growth stage,indicating that intercropping was beneficial to the accumulation of dry matter in maize.Under the model of intercropping,the dry matter accumulation of intercropping maize at the N application level of N2(300 kg · hm-2)was significantly higher than that of other N application rates,which indicated that the reasonable N application level could play a better role in improving the dry matter accumulation advantage of intercropping maize.The dry matter accumulation of grain,leaf,bract and stem in intercropped maize were significantly higher than that of monoculture maize in the same N level,indicating that intercropping could develop the advantage of grain,leaf,bract and stem dry matter accumulation.In the intercropping mode,the dry matter accumulation of grain,leaf,bract and stem of maize with N2(300 kg · hm-2)application level was significantly higher than that of other N levels,indicating that the nitrogen level of 300 kg · hm-2 was the most suitable application level to increasing the dry matter accumulation of maize grain,leaf,bract and stem.With the increase of N application rate,the proportion of grain in the whole plant decreased while the proportion of stem and bract in the whole plant increased.However,the results showed that the change range of monoculture maize was higher than that of intercropping,indicating intercropping could relieve the situation of dry matter accumulation reduction in the maize grain induced by the excessive N application.Before the flowering of intercropping maize,the translocation rate of assimilation stored in stem and bract at different N levels were significantly lower than that of monoculture.The contribution to grain of assimilates storedin leaves and bract also showed a same result.The contribution rate to grain of leaves,stem and bract dry matter accumulation after flowering of intercropping maize were significantly higher than that of monoculture maize under different N application rates.Compared with the N2 treatment(300 kg · hm-2),the contribution rate to grain of leaves,stem,and bract dry matter accumulationg in N3 treatment(450 kg · hm-2)decreased by 0.72%and 2.17%and 1.86%,respectively,indicating that excessive N application could inhibit the contribution to grain of dry matter accumulation of various organs of intercropping maize after flowering.(2)Intercropping maize in winter wheat/spring maize system has the advantage of N accumulation,absorption and utilization.The N accumulation in maize at different growth stages increased at first and then decreased with the increase of N application rate.The N accumulation in maize reached the 1aximmV value under the N2(300 kg · hm-2)levels.At the late growth stage of maize,the same nitrogen level,the intercropping maize N accumulation were significantly greater than monoculture maize,indicating that intercropping has the advantage of significantly increasing the N accumulation.The nitrogen use efficiency of intercropping maize was significantly higher than that of monoculture maize.The NPFP,NPE,and ANUE were higher than that of monoculture maize by 8.72%,10.15%and 14.77%respectively.Under the N application rate of 300 kg · hm-2,the contribution to grain of intercropping maize leaves was significantly higher than that of monoculture maize.And under N2(300 kg · hm-2)the contribution to grain of intercropping maize leaves was significantly higher than that of intercropping maize in other N treatments,which indicated that the reasonable supply of N fertilizer improved the N transfer from leaves to grain of intercropping maize.(3)In winter wheat/spring maize system,intercropping maize has the advantages of phosphorus accumulation,absorption and utilization.Under N application rate of N2(300 kg·hm-2),after maize silking stages,the phosphorus accumulation of intercropping maize was significantly higher than that of monoculture.The results showed that the intercropping could improve the phosphorus accumulation during the maize growth period in suitable nitrogen application.Under different N application levels,the grain,leaf,bract and stem of intercropping maize and monoculture maize had no significant difference in phosphorus proportion aspect.The phosphorus accumulation of intercropping maize was significantly higher than that of monoculture maize under the high N application rates(N2(300 kg·hm-2)and N3(450 kg·hm-2)),indicating that intercropping could increase the phosphorus accumulation of maize grain in the high N application levels.The phosphorus accumulation of grain,leaf,bract and stem in intercropping maize with N2(300 kg·hm-2)application level was significantly higher than those with other N treatments.The results showed that N2(300 kg-hm-2)performed best in increasing phosphorus accumulation in grain,leaf,bract and stem of intercropping maize in mature stage.The leaf’s PCP and PPE of intercropping maize were significantly greater than that of monoculture maize under nitrogen application rate of N1(150 kg·hm-2).The stem’s PCP of intercropping maize were significantly greater than that of monoculture maize under N application rate of N2(300 kg·hm-2).The results showed that intercropping could increase the utilization rate of maize phosphorus.Under the intercropping mode,the N application rate of N2(300 kg·hm-2)and N3(450 kg-hm-2)were beneficial to the transportation of phosphorus of maize leaves to grain,also the N application rate of N2(300 kg·hm-2)is beneficial to the transportation of phosphorus of maize stem to grain,indicating that higher nitrogen application rate could promote the phosphorus transportation of maize leaf,bract and stem to grain. |
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