| In the intercropping of maize and soybean,it is of great significance to find a reasonable field collocation pattern to increase soybean yield and further develop the intercropping advantage.In this experiment,the effects of different bandwidths(A1:2.0 m,A2:2.2 m,A3:2.4 m)and soybean planting densities(B1:90000 plants/hm~2,B2:112500plants/hm~2,B3:135000 plants/hm~2,B4:157500 plants/hm~2)on the light environment,day matter accumulation and yield of soybean were studied under the intercropping of maize and soybean.On this basis,the effects of planting density(D1:67500 plants/hm~2,D2:90000plants/hm~2,D3:112500 plants/hm~2,D4:135000 plants/hm~2)on photosynthetic function,dry matter accumulation and distribution and yield formation of intercropping soybean(MS)were studied by single cropping(SS).The main results showed as follows:1.Bandwidth expansion can significantly increase soybean canopy light transmittance.At different densities,the transmittance of soybean canopy increased first and then decreased.Compared with single cropping(SS),intercropping soybean(MS)was affected by the shading effect of maie,and the light transmittance of canopy and middle section was significantly reduced(the light transmittance of single cropping canopy was 100%).In V5and R2 stages,the light transmittance of middle section of SS was 2.09 and 5.83 times that of MS.This suggests that the lower middle part of intercropping may suffer more severe shading.2.Compared with SS,the leaf structure and photosynthetic function of MS are changed,which is manifested by the decrease of LAI,the extension of photosynthetic time but the decrease of photosynthetic function,and the higher the density,the greater the change.The antioxidant enzyme activity of MS in functional leaves was higher than that of SS at different stages.This indicated that the leaf senescence of soybean was effectively delayed,leaf photosynthesis time was prolonged and leaf maturation period was prolonged during intercropping of maize and soybean.This is a manifestation of abnormal leaf aging.Green leaves are the phenotype.Green leaves will cause late ripening of plants,which is not conducive to the increase of yield.In addition,with the increase of planting density and the deepening of leaf greenness,the SOD,3.The expansion of bandwidth was beneficial to the accumulation of soybean dry matter and the transfer of preflowering vegetative organs to pods.The increase of density was not conducive to the accumulation of soybean dry matter and the transfer of dry matter to pod before flowering.Compared with SS,the dry matter accumulation per plant and population of MS decreased,and the transfer amount,transfer rate and contribution rate of pre-flowering dry matter to pod decreased by 26.7%,6.0%and 10.9%respectively.4.Bandwidth expansion was beneficial to improving soybean grain filling,and average grain filling rate and grain weight of A3 increased by 1.4%,0.8%and 0.3%0.5%compared with A1 and A2.With the increase of planting density,the maximum grain filling rate(Rmax),the maximum time growth rate(Wmax)and the average grain filling rate(Vmean)of intercropping soybean all showed a decreasing trend,and the hundred-grain weight all decreased.It indicates that the increase of planting density is not good for seed development.The maximum grain filling rate time(Tmax),Vmean and Wmax of MS were all higher than SS,and the final grain weight was higher than SS.5.In maize and soybean intercropping,the bandwidth expansion is beneficial to the increase of soybean yield.When the intercropping bandwidth was A3(2.4 m),the100-grain weight,grain number per plant and effective plant number of soybean increased significantly,and the yield of A3 increased significantly by 15.9%and 28.3%compared with that of A1(2.0 m)and A2(2.2 m).With the increase of density,soybean yield showed a decreasing trend,and the soybean yield of B3(135000 plants/hm~2)and B4(157500plants/hm~2)significantly decreased by 10.8%and 17.9%compared with that of B1(90000plants/hm~2).In each treatment,the peak of soybean yield was A3B1,and the peak of system yield was A1B2.There was no significant difference in system yield under each bandwidth.Compared with SS,the number of seeds per plant,the number of effective plants,the yield per plant and population in MS significantly decreased by 24.5%,15.2%,21.1%and33.1%.The increase of planting density is not conducive to the formation of intercropping soybean yield.The grain number per plant of MS significantly decreases with the increase of density,and the effective plant number varies within the range of 57000-82500plants/hm~2.The higher the planting density is,the higher the loss rate of effective plant number is.When intercropping soybean was low density:67500 plants/hm~2(MS6.75)and90000 plants/hm~2(MS9.00),the yield components were better,the soybean yield was higher,and the intercropping system yield was higher.6.Under the intercropping system of maize and soybean,expanding the bandwidth can significantly increase the soybean yield,and has no significant impact on the yield of maize and soybean systems.Under the current background of responding to mechanized farming,expanding the intercropping bandwidth to 2.4 m is a recommended configuration mode.Under different soybean planting densities,the LER of intercropping was all greater than 1,indicating that corn and soybean intercropping had certain advantages.When the intercropping soybean density was low,the LER was higher.It indicates that in sichuan area,the soybean density should not be too high in intercropping.When the bandwidth is2.4 m,the planting density of soybean can be selected to be 67500-90000 plants/hm... |
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