Analysis On Interspecific Root Competition And Benefit Of Fruit + Bean Agroforestry System

In order to analyze the temporal and spatial distribution of roots,interspecific root competition,farmland microclimate and economic benefits in fruit+soybean agroforestry system,two fruit-bean intercropping patterns of malus（Malus spectabilis（Ait.）Borkh.）+soybean（Glycine max（Linn.）Merr.）（MS）and plumcot（Prunus simonii Carr.）+soybean（PS）were set up in Yining County,Xinjiang in 2020 and 2021.The root length density（RLD）and specific root length（SRL）of different plants in 0-60 cm soil layer in the system were measured by Win RHIZOTM,and the fine root vertical center,competitiveness index and interspecific relative competitiveness were calculated.Meanwhile,air temperature,relative humidity,wind speed and windbreak efficiency of the two fruit+bean agroforestry systems were measured.Combined with the comprehensive analysis of dry matter quality,yield and economic benefits.Through the study of root distribution,crop growth and development,farmland microclimate change and profit of fruit+bean agroforestry systems,this thesis reveals the interspecific competition strategy of fruit+bean agroforestry systems,finds a fruit bean composite planting combination that takes into account ecological and economic benefits for the development of new forest and fruit industry in Ili area,and finds a new solution to improve the income of farmers in the early stage of fruit tree planting.The main research results are as follows:1.Fruit+bean agroforestry system has a significant effect on the temporal and spatial distribution of plant roots.Soybean roots are mainly distributed at 0-20 cm soil depth and 150-200 cm away from the tree,which decreases with the increase of soil depth and the decrease of distance from the tree.The RLD of soybean was as follows:sole-cropping（Sole）>soybean+malus（Int-MS）>soybean+plumcot（Int-PS）,and SRL shows the trend of Int-PS>Int-MS>Sole.RLD of intercropping fruit trees was lower than that of monoculture,and SRL was higher than that of monoculture.RLD increased and SRL decreased with the passage of growth stage.The roots of intercropping malus（INT-MS）are mainly distributed in the soil depth of 20-40 cm.With the growth stage,the downward displacement of fine root vertical center increased.The roots of intercropping plumcot（INT-PS）are mainly distributed in the soil depth of 0-20 cm.With the growth stage,the downward displacement of the fine root vertical center decreased,and the RLD increases at 150-200 cm away from the tree.The competitiveness index of INT-PS was significantly higher than that of Int-PS;the competitiveness index of Int-MS at 0-20 cm was higher than that of INT-MS at 20-60 cm.2.In the fruit+bean agroforestry system,plants adopt different interspecific competition strategies.Soybean fine roots become a strong competitor in the surface soil of fruit+bean agroforestry system by increasing SRL and reducing root weight.INT-MS reduced niche overlap and resource competition with Int-MS by moving down the root distribution center,prolonging root length and increasing root weight.By reducing SRL and increasing root weight,INT-PS enabled the root system to use the obtained growth resources more for growing new roots in the horizontal direction.Even though the overall interspecific relative competitiveness of fruit trees was stronger than that of soybeans in the system,the competitiveness of soybeans was still stronger than that of fruit trees in local soil sites.3.The fruit+bean agroforestry system can effectively improve the farmland microclimate.The air temperature of fruit+bean agroforestry system increased with the increase of external temperature.The occurrence time of daily maximum temperature in flowering-pod stage and grain filling period was later than that in sole-cropping soybean.Compared with Sole,the average air temperature of MS and PS in the whole growth period was 2.28℃and 1.28℃lower respectively.The relative indexes of air relative humidity of MS and PS systems were 123.16%and 112.16%respectively.The fruit+bean agroforestry system can significantly reduce the wind speed in the field,and with the increase of wind speed,the wind prevention efficiency improves.When the wind speed in the system reaches about 2.2m·s^-1,the windproof efficiency of MS and PS can reach 44.52%and 42.46%4.The fruit+bean agroforestry system has high economic benefits.Between the fourth-node stage to Beginning pod stage,the dry matter quality maintained a high growth rate.The dry matter quality of Int-MS was higher than that of Sole and Int-PS.The yields of Int-MS and Int-PS decreased by 34.12%and 41.97%respectively compared with Sole.There was no significant difference in soybean yield between the two intercropping.The land equivalent ratio（LER）and income equivalent ratio（IER）of MS and PS composite system were greater than 1.The total profit of fruit+soybean agroforestry system was 3.73-4.34 times that of sole-cropping soybean and 0.02-0.08 times that of corresponding sole-cropping fruit trees.In particular,MS compound system has more economic benefits.In this experiment,the fine root distribution of malus in MS agroforestry system was separated from that of soybean,the system competition was weaker than that of PS,and the farmland microclimate effect was more prominent.Intercropping ensured that the temperature in the system was maintained in the appropriate growth range of soybean,so as to reduce the damage of bad weather conditions to crops in this area.The dry matter quality of Int-MS was higher than Int-PS,and the soybean yield and fruit yield of MS are higher than PS,which was more economical.Malus+soybean agroforestry system was a more suitable agroforestry pattern for planting in this area.