Effect Of Wheat-pea Intercropping And Mixed Cropping On Crop Population Growth And Grain Quality And Yield Effect Of Subsequent Crops

The limited arable land area is an important reason that hinders the increase of total grain production in China.To ensure food security,increasing productivity per unit area of land is still a problem that needs to be solved at present.Planting patterns by constructing composite groups have become an important technology to improve the efficiency of agricultural resource utilization and crop yield,as well as a potential technical way to promote resource-saving and environment-friendly production patterns in agriculture.Based on this,this study was conducted in 2019-2021.Two intercropping methods were set up under the conventional sowing rate of 195 kg/hm²of wheat and 150 kg/hm² of peas:four rows of wheat+two rows of peas（W4P2）and two rows of wheat+two rows of peas（W2P2）;simultaneous setting of two mixing methods:a conventional sowing rate of wheat and peas in the same row（WP1）,and a conventional sowing rate of 70%each of wheat and peas in the same row（WP2）;and the control of 195 kg/hm²（CKW）for wheat and 150 kg/hm²（CKP）for pea,to investigate the photosynthetic physiological characteristics,root traits,population productivity,quality and yield of subsequent crops of the crop under the coupling effect of gram-pea complex planting,in order to provide a theoretical basis for the construction of a high light efficiency production and high yield planting model for intercropping and mixed cropping.The main research results are as follows:（1）Compared to monoculture,intercropping and mixed cropping significantly improved photosynthetic characteristics of wheat and reduced photosynthetic characteristics of the inferior crop pea.The chlorophyll content of wheat in the W2P2treatment was the highest among the intercropping treatments,increasing by 7.0%-7.5%（P<0.05）at anthesis compared to the monocrop treatment;the net photosynthetic rate（Pn）of single leaves in intercropped wheat increased by 0.8%-9.3%（P<0.05）compared to CKW,respectively.The mixed treatments significantly increased the chlorophyll content（SPAD）of wheat,with an increase of 4.4%-9.6%（P<0.05）compared to the monocrop treatment when SPAD reached its highest value at the flowering stage;the net photosynthetic rate（Pn）of single leaves of mixed wheat reached its highest value at the flowering stage,with an increase of 10.8%and 16.6%（P<0.05）in the Pn values of the two-year WP2 treatment compared to the monocrop CKW treatment.Both SPAD and Pn of intercropped peas were reduced to varying degrees compared to the monocrop treatment CKP,with the highest Pn of peas in the mixed treatment WP2 and intercrop treatment W2P2.The Canopy apparent photosynthesis（CAP）at flowering stage was significantly increased by 5.5%and 4.4%（P<0.05）in intercropping treatment W2P2 for two years compared to control population CAP_CK22;Canopy apparent photosynthesis（CAP）increased significantly in the mixed treatment compared to the monocrop treatment,reaching a maximum value of 31.4μmol CO₂ m^-2s^-1 at anthesis in 2021 for the WP2 treatment,an increase of 14.8%compared to the monocrop wheat and 38.2%compared to the monocrop pea.（2）In intercropping and mixed cropping systems,crop roots grow crosswise and interact with each other.The intercropping and mixed cropping significantly affected the root growth of wheat.The root weight of wheat increased by 17.4%-27.9%（P<0.05）in intercropping treatments compared to monocropping,and the root length density and root surface area of wheat were greater with W2P2.The root length density and root weight of wheat in the mixed cropping treatment increased significantly compared with the monocrop treatment（P<0.05）,while the root surface area was no significant difference,and the root length density of wheat became larger as the sowing density decreased;WP2 root weight was the largest in the mixed treatment,which increased by 38.0%and 36.9%（P<0.05）in two years compared with the monocrop treatment.The growth of pea roots was inhibited in intercropping and mixed cropping.Pea root length density was reduced by 17.5%-26.4%and27.9%-35.5%;root surface area was reduced by 7.1%-13.7%and 20.6%-25.3%;root dry weight was reduced by 11.9%-22.0%and 20.0%-35.0%,respectively,in the intercropping and mixed crop treatments compared to the monoculture treatment（P<0.05）.（3）Intercropping and mixed cropping increased dry matter accumulation of wheat and decreased dry matter accumulation of peas.At maturity,wheat dry matter accumulation was significantly higher in the intercropping treatment W2P2 than in the monoculture treatment by 17.9%（P<0.05）,and wheat dry matter accumulation increased by 8.1%-16.8%（P<0.05）in the mixed cropping treatment compared to the monoculture treatment.Pea dry matter accumulation at maturity was significantly higher in the intercropping treatment W2P2 than in the W4P2 treatment by 8.1%（P<0.05）.The dry matter accumulation of peas in the mixed cropping treatment was reduced compared to the CKP treatment.（4）The intercropping treatment and mixed cropping treatment significantly increased the competitiveness of the wheat crop in the composite population,thus increasing the population yield of wheat and peas and improving land use compared to monoculture,with a land equivalent ratio of 1.02-1.66.On a per unit area,the increase in yield of wheat grown in intercropping and mixed cropping was mainly due to the increase in the number of ears and grains,the yield of intercropped wheat showed that W2P2>W4P2>CKW and the yield of mixed wheat showed that WP2>WP1>CKW.Intercropped and mixed pea yield was reduced by the decrease in effective pod number and grain number.In both years,the pea yields of all the intercropping treatments were higher than those of the mixed treatments,with W2P2having higher pea yields of 2306.2 kg/hm² and 2401.5 kg/hm² among the two intercropping treatments and WP2 having higher pea yields of 1229.7 kg/hm² and1362.3 kg/hm² among the two mixed treatments,respectively.The total crop yield size of intercropping and mixed cropping treatments showed WP2>WP1>CKW>W4P2>W2P2>CKP,and the total yield of and mixed cropping was significantly higher than that of monocropping and intercropping.The total yield of and mixed cropping treatment W2P2（4742.0 kg/hm²）was significantly increased by 11.2%（P<0.05）compared to the control population yield Y_CK22.The mixed crop treatment WP2had the highest total yield（8096.7 kg/hm²）,which was significantly increased by 36.0%and 214.2%（P<0.05）compared to wheat and pea monocultures,respectively.（5）Intercropping and mixed cropping of gram and bean significantly affected the quality of the crop.Wheat protein content,starch content,wet gluten content and sedimentation value of intercropping and mixed cropping treatments were not significantly increased in 2020 compared to monoculture,but in 2021,all these quality indicators were significantly increased compared to monoculture（P<0.05）.Wheat quality was higher in the intercropping treatment W2P2 and the mixed treatment WP2.The protein content of peas in the intercropping and mixed cropping treatment was lower compared to the monocrop treatment,and ash content was higher in the W2P2 treatment,increasing by 13.2%and 2.4%in both years（P<0.05）,respectively,compared to the monoculture treatment.（6）Gram-bean intercropping and mixed cropping had a significant effect on the growth and development of the subsequent crop by improving soil nutrients and fertilizing the ground,and the average yield size of corn in both years was WP2>W2P2>WP1>W4P2>CKP>CKW.The interaction of year,planting method,and year and planting method highly significantly affected the ears length and ears grain size of maize.The intercropping and mixed cropping treatments significantly increased the seed yield of corn in the following crop compared with the monoculture treatment.In conclusion,70%of the conventional planting density of wheat and pea in the same row,namely WP2 treatment,can improve the population yield through rational utilization of ecological resources,improve the yield of dominant crop wheat,and provide a good soil environment for the subsequent crops,so as to achieve high yield,efficiency and quality of farmland.