Effects Of Plastic Film Mulching And Hole Sowing On Seed Yield Of Alfalfa Under Subsurface Drip Irrigation

The technology of plastic film mulching has been extensively popularized and used in crops for its fruitful satisfactory achievement and ever-increasing matures approach.Number of studies have been focus on the application in cotton and maize,while little attention about the utilities of plastic film mulching in Medicago sativa.This study investigated the seeds production of Alfalfa coupled with subsurface drip irrigation,plastic film mulching and hole sowing,so as to improved seed production and quality as well as economic benefits.Eventually,the methodology in this study can be helpful for standardized and large-scale production.The seeds of Medicago sativa were treated with plastic film mulching and hole sowing with different density planting.The three treatments are as fellow:T1(Treatment 1)with 9 cm plant spacing,60 cm row spacing and 60 cm distance from drip irrigation zone;T2(Treatment2)with 8 cm plant spacing,60 cm row spacing and 60 cm distance from drip irrigation zone;T3(Treatment 3)with 18 cm plant spacing,50 cm row spacing and 70 cm distance from drip irrigation zone.While CK without plastic film mulching but with 9 cm plant spacing,60 cm row spacing and 60 cm distance from drip irrigation zone.In order to investigate the effect of drip irrigation under film mulching and planting density differences on alfalfa growth and seed yield,the plant height,branch number,flower number,flower bud and inflorescence of racemes were observed.In addition,the changes of soil water state were measured after each irrigation.The results are as fellow:(1)The plant height,branch number,number of bud,flower number and pod number of alfalfa with plastic film mulching were more than the CK,which indicated that the plastic film mulching had a positive effect on vegetative and reproductive growth of seed yield.(2)The water come from underground drip irrigation mainly distributed range from 0 cm to 40 cm,which is inconsistence with the vertical distribution of alfalfa root.Obviously,the soil moisture content within topsoil was significantly higher than that of CK.In addition,this soil moisture content can last long about 10 days.Therefore,small amount of irrigation contributes positive effect on precise regulation of alfalfa growth.Drip irrigation associated with plastic film mulching can reduce the evaporation from soil moisture a lot and the loss of soil moisture.Which eventually improve irrigation water use efficiency of 234-267%than without covering.(3)The seed production of T1,T2,T3 and CK are 228.67 kg/hm~2,225.43 kg/hm~2,222.93kg/hm~2 and 67.51 kg/hm~2,respectively.However,there was no significant difference between them.This may attribute to fewer branches in the first growth year of alfalfa.The significant difference between CK and plastic film mulching indicated that plastic film mulching exerted more influence on seed yield compared with the influence of density.(4)The Medicago sativa had higher root system in soil layer covered by plastic film mulching that that without covering,which suggested that film mulching had a certain promoting effect on the root growth of alfalfa.(5)Soil salty migrated with irrigation wetting.The soil salty with the treatment of T1,T2,T3 mainly migrated to the soil layer with 40-50 cm depth.However,there was no significant salty accumulation result from immediate water loss.(6)The mechanized operations(improved integration of tape laying,plastic film mulching and hole sowing)has improved the ratio for input and output to 300%.Furthermore,the mechanized operations lay the groundwork for formalized and standardized production technology as well as improve the feasibility of the application of tape laying-plastic film mulching-hole sowing technology integration.