Effects Of Field Configuration On Soybean Light Utilization,Intraspecific Competition,and Yield Benefits Under Maize-soybean Relay Strip Intercropping System

Intercropping can improve land use efficiency and dry matter production through different row configuration.The crop morphogenesis and yield depend on the light interception in different row spacing.In order to find out the effects of different row configuration on the light environment,morphology,yield and system benefit of banded width under maize-soybean relay intercropping system,the high quality and high yield row spacing of soybean was realized.A single factor random block design was used for this experiment.Five treatment with 3 bandwidths and 3 row ratios?T1:bandwidth 2 m,row ratio 2:2;T2:bandwidth 2.4 m,row ratio 2:3;T3:bandwidth 2.4 m,row ratio 2:4;T4:bandwidth 2.8 m,row ratio 2:3;T5:bandwidth 2.8 m,row ratio 2:4?were set as intercropping system?corn and soybean row is 40 cm?and sole cropping maize?CKM?,sole cropping soybean?CKS?was used as control.The main results of variance analysis and correlation analysis of the experimental data are as follows:1.During the co-growth period of maize and soybean,different bandwidth and row ratio directly affect the transmittance of soybean leaf canopy.The canopy transmittance of monoculture was significantly higher than all intercropping system,the transmittance of soybean canopy increased with the increase of bandwidth,and the maximum and minimum values appeared in T4 and T1 treatments,which were 91.8%and 69.57%,respectively.Under the same bandwidth,there was no significant effect on the canopy transmittance of middle row soybean by changing the row ratio.The minimum transmittance of soybean in lateral line appeared in T3 treatment,which was 2.91%,4.35%,13.36%and 5.05%lower than that of T1,T2,T4 and T5,respectively.Under the same bandwidth,different row ratios had a significant effect on the transmittance of edge row soybean canopy.The light of intercropping system in symbiotic period showed"V"distribution,and the photosynthetic active radiation of soybean canopy increased gradually with the increase of bandwidth.After maize harvest,the light distribution of soybean canopy was uniform and the bandwidth had no significant effect on photosynthetic active radiation of soybean canopy.2.With the increase of bandwidth,the stem diameter of soybean under intercropping increased gradually at the five-leaf stage and the initial flowering stage.the maximum values were 8.13 mm?T4?and 5.41 mm?T5?at the initial flowering stage,respectively.The stem diameter of CKS was significantly higher than that of intercropping.The leaf area index decreased at first and then increased at the five-leaf stage,chlorophyll a,chlorophyll b and total chlorophyll decreased gradually,and the maximum value was showed in T1 treatment.There was a significant positive correlation between chlorophyll a,chlorophyll bar b and total chlorophyll and the maximum values were 2.11 mg/g,1.87mg/g and 4.00 mg/g of chlorophyll a,chlorophyll b and total chlorophyll,respectively.The chlorophyll values were negatively correlated with the transmittance of soybean canopy.The net photosynthetic rate were 21.61?mol·m^-2·s^-1 and 20.83?mol·m^-2·s^-1 under2.8 m bandwidth in both 2 years was the highest in T5 treatment,respectively.There was a significant positive correlation between the net photosynthetic rate and the transmittance of soybean canopy.3.With the gradual increase of bandwidth,the dry matter of soybean organ and dry matter per plant of intercropping soybean at the beginning of flowering stage showed an increasing trend,which was positively correlated with the transmittance of soybean canopy.The leaf dry weight,stem dry weight and dry matter in T4 were 10.79 g,14.24 g and 25.12 g,respectively,and T5 were 4.23 g,4.81 g and 9.48 g,respectively.At the flowering stage and pod filling stage,the dry weight of leaf,stem and dry matter per plant in T4 were 10.79 g,14.24 g and 25.12 g,respectively,and T5 were 4.23 g,4.81 g and9.48 g,respectively.The dry matter distribution of soybean in each intercropping treatment was that the stem dry weight was higher than leaf and the sole cropping was significantly higher than intercropping.4.With the increase of bandwidth,the root-shoot ratio of intercropping soybean increased at first and then decreased.The maximum and minimum values of T3 and T4 at flowering stage and pod stage were 0.11?T3?and 0.09?T4?,0.16?T3?and 0.11?T4?,respectively,which were negatively correlated with dry matter and interspecific competition between soybean and maize.The relative competition severity of soybean intercropping in the planting belt decreased.The relative competition severity of T4treatment was significantly lower than that of other treatments.The relative competition severity of soybean has insignificant influence at the same bandwidth and different row,which was positively correlated with the interspecific competition between maize and soybean,which was 0.023 and 0.103 in two years,respectively.The relative competition severity of soybean was not significantly correlated with the ratio of root to shoot.The relative crowding coefficient of maize under T1 and T3 was higher than that of soybean,which was 33.61 and 8.67 in T1 and 6.36 and 8.83 in T3,respectively.5.The Light interception,yield per unit area light,use efficiency of soybean and the solar energy value increased gradually with the increase of bandwidth.The maximum value of soybean yield appeared in T4 treatment and the yield was 2735.49 kg/hm²,1733.79 kg/hm²,and the light use efficiency was 0.34%and 0.24%in two years,respectively.Considering the total yield,land equivalent ratio and solar energy value of the system,the maize-soybean relay strip intercropping system can be moderately expanded to 2.4m,and the population structure can be optimized and the yield of soybean can be increased by selecting maize and soybean row ratio 2:3.