Effect Of Nitrogen Application On Growth And Yield Formation Of Foxtail Millet And Peanut Under Intercropping Mode

In order to explore the effects of different nitrogen application levels on crop growth,physiological characteristics and yield under intercropping mode of foxtail millet and peanut,a field experiment with foxtail millet and peanut 2:2 intercropping mode was set up in Jiyang experimental base of Shandong Academy of Agricultural Sciences in 2018 and 2019,combining with four nitrogen application levels,N0（0kg/hm²）,N1(75 kg·hm^-2),N2(150 kg·hm^-2),N3(225 kg·hm^-2).The effects of Nitrogen Application on dry matter accumulation,plant characters,nitrogen accumulation,protective enzyme activity,photosynthetic characteristics,yield and yield components were studied.The main results are as follows:The dry matter accumulation in the aboveground part,the stem diameter,panicle length and panicle diameter of intercropping foxtail millet were increased,but the plant height was reduced.For peanut,the amount of dry matter accumulation per plant in each growth period of intercropping was lower than that of sole cropping.At the same time,the height of main stem and the length of lateral branches were increased,and the the number of branches and nodes of main stem were reduced.Nitrogen application can promote the growth of foxtail millet and peanut,increase the dry matter accumulation of foxtail millet and peanut,and improve the agronomic traits of foxtail millet and peanut.Under intercropping mode,the accumulation of nitrogen in peanut organs was reduced,while that in foxtail millet organs was increased.Before the pod setting stage of peanut,the distribution of nitrogen was:stem>leaf>root.From the pod setting stage to the full fruit stage,the distribution of nitrogen was:pod>stem>leaf>root.At the maturity stage,the distribution of nitrogen in all organs of foxtail millet was:panicle>leaf>stem.In addition,nitrogen application significantly increased the accumulation of nitrogen in all organs of foxtail millet peanut under different planting patterns.The activities of SOD,POD and CAT in flag leaf of intercropped foxtail millet were higher than that in sole cropping during each growth period;the activities of SOD,POD and CAT in the functional leaves of intercropped peanut were lower than that of the peanut.In addition,the MDA content in flag leaves of intercropped foxtail millet at all growth stages was reduced;on the contrary,intercropping conditions made the MDA content of peanut increased.The application of nitrogen can increase the activities of SOD,POD and CAT in the leaves of peanut and foxtail millet at different growth stages,and decrease the content of MDA in the leaves.The Pn,Gs and Tr of flag leaf in intercropped foxtail millet were significantly higher than that in sole cropping,and Ci decreased significantly.Different from foxtail millet,peanut of intercropping was at a disadvantage in light competition,which showed that Pn,Gs and Tr of functional leaves are significantly reduced,and Ci increased significantly in intercropping.Nitrogen application significantly increased Pn of foxtail millet and peanut at different growth stages,increased photosynthetic capacity of foxtail millet and peanut,and slowed down the decline of photosynthetic capacity caused by intercropping on peanut.Planting pattern and nitrogen application level had significant effect on the yield of foxtail millet and peanut,but the two factors had no interactive effect on the yield of faxtail millet and peanut.Under the condition of equal area,intercropping significantly increased the yield of foxtail millet,with an average increase of18.9%-23.0%in two years;at the same time,the average yield of peanut decreased by12.3%-17.6%in two years.Nitrogen application significantly increased the yield of foxtail millet under different planting patterns.The yield of foxtail millet increased by7.4%-22.4%under nitrogen application,and reached the highest at the level of N2(150 kg·hm^-2),which was 7750.0 kg·hm^-2 and 7906.3 kg·hm^-2 respectively in two years.The yield of peanut increased by 5.9%-28.9%under nitrogen application,and reached the highest in two years at the level of N2(150 kg·hm^-2),which was 4781.3kg·hm^-2 and 4875.0 kg·hm^-2,respectively.The theoretical optimum amount of nitrogen application for the highest yield of single cropping millet is 226 kg·hm^-2 on average in two years,158 kg·hm^-2 for peanut and 173 kg·hm^-2 for intercropping system.The intercropping of millet and peanut can obtain higher yield under the condition of reducing nitrogen input.The land equivalent ratio（LER）of the intercropping system of foxtail millet and peanut was greater than 1 under all nitrogen application levels,which proved that the intercropping mode of foxtail millet and peanut had yield advantage.In addition,the land equivalent ratio（LER）of the intercropping system of foxtail millet and peanut was the highest at N2 level.Although the nitrogen partial productivity of intercropping system of foxtail millet and peanut decreased by 5.6%-9.4%on average compared with foxtail millet of sole cropping in two years,it increased by21.9%-25.8%on average compared with peanut of sole cropping;the agronomic utilization efficiency of nitrogen fertilizer in intercropping system was significantly higher than that of peanut of sole cropping,and increased first and then decreased with the increase of nitrogen application,and reached the highest at N2 level in two years.To sum up,the intercropping system of foxtail millet and peanut is a high-yield and efficient composite system,the whole intercropping system has a higher yield advantage,which mainly comes from foxtail millet;And N2 is the best nitrogen application level in the intercropping system of millet and peanut,that is,when the nitrogen application amount is 150 kg·hm^-2,millet and peanut can coexist more harmoniously.