Study On The Response Mechanism Of Environmental Factors On Nutrients And Field Regulation Strategy In The Process Of Alfalfa Drying

At present,the planting area of alfalfa in China is increasing year by year.However,due to the uneven quality of alfalfa hay,the market competitiveness of alfalfa hay is relatively poor.Quality alfalfa hay relies heavily on imports,and the price is high.Therefore,the quality of alfalfa hay becomes the key link to improve the alfalfa hay market competitiveness.In order to solve the key technical problems that restrict the production of good quality alfalfa hay in China(environmental conditions and harvesting techniques during drying),screen the main environmental factors affecting the natural drying of alfalfa,reveal the response mechanism of the change of the major environmental factors on nutrients in the drying process,and the corresponding relationship between nutrients and chlorophyll in this process,formulate the control strategy for high quality alfalfa hay production in field.The purpose of this study is to provide theoretical basis and technical support for the rapid identification of the quality of hay nutrition by the color of hay in the large-scale production and trade of high quality alfalfa in north China.The experimental area is located in the city of Baotou,Inner Mongolia region,alfalfa cultivar "WL232HQ" was used as the research material,the main environmental factors affecting the natural drying of alfalfa were screened through the plot test.Combined with the artificial climate box test,the response process and variation rule of the change of major environmental factors on major nutrients were explored.The optimal cutting period and cutting time were determined by field experiment,form the control strategy of alfalfa hayfield production,And through the correlation between chlorophyll and the main nutrients of hay,explore the feasibility of identifying the quality of hay by the color of hay.The comprehensive test results were analyzed and evaluated systematically,the results are as follows.1.During environmental factors(air temperature,air humidity,solar radiation intensity,wind speed,ground temperature,ground humidity,atmospheric water potential),solar radiation intensity,air temperature,air relative humidity and wind speed are the main influencing factors to control drying rate;Solar radiation intensity,air temperature and wind speed are the key factors to control chlorophyll content.Air temperature,air humidity and wind speed are the key factors to control major nutrients(crude protein CP,neutral detergent fiber NDF,acidic detergent fiber ADF).The main factors influencing hay CP of alfalfa are temperature and wind speed,and the main factor affecting NDF,ADF and relative feeding value(RFV)is air humidity.Comprehensive measurement shows that solar radiation intensity,air temperature,air humidity and wind speed are the main environmental factors affecting the natural drying of alfalfa.2.The response of alfalfa drying rate,main nutrients and chlorophyll to environmental factors are as follows:?The solar radiation intensity in the range of 200?350 w/m2 is positively correlated with the drying rate and major nutrients,and negatively correlated with the content of chlorophyll.?The temperature within 15 ?27 aC was positively correlation with the drying rate;During 0?12 h(physiological drying stage),temperature was negatively correlated with chlorophyll content and main nutrients.In the whole drying process,the temperature was positively correlated with the content of chlorophyll and the main nutrients.?The relative humidity of the air was negatively correlated with drying rate,chlorophyll content and main nutrients in the range of 35?50%·?The wind speed was positively correlated with the drying rate in the range of 1.5?3.1 km/h.The content of chlorophyll and the main nutrients presented a single peak curve(the peak was 2.2 km/h).3.?When the best mowing period(from bud to flower)is missed in producing alfalfa hay in the field,it can be delayed to mid-flowering period(25%?30%of alfalfa flowering).Although the content of CP,RFV and total chlorophyll decreased,However,the quality of forage can be ensured to the maximum extent(compared with the optimal mowing period,the content of hay CP in the mid-flowering period is 87.13%?95.32%,RFV is 91.02%?96.71%,and the total chlorophyll content is 83.7%?84.9%).The dry rate of alfalfa,total chlorophyll content of hay,CP and RFV of mowed alfalfa between 8:00 and 12:00 were better.Before the beginning of autumn,if the climatic condition of mowing pernod better,and the variation range of daily environmental parameters during harvest is small,mowing time can be appropriately extended to 14:00-16:00,but the mowing time after autumn can't done after 12:00.4.The content of hay chlorophyll in alfalfa can be used as an important indicator to measure the level of hay CP,NDF,ADF and RFV.The nutritive quality and grade of alfalfa hay can be identified by the degree of hay fresh green in production.In the correlation degree,the chlorophyll content of whole plant,stem and leaf of alfalfa hay was positively correlated with CP and RFV,and negatively correlated with NDF and ADF.The regression models of total chlorophyll of hay and CP,NDF,ADF and RFV are as follows:ycp?11.515x+13.468(R2 =0.606,/P<0.0001),yNDF?-2.753x+54.150(R2=0.676,P<0.0001,yADF=)2.298 x+47.085(R2 =0.669,P<0.0001),yRFV=10.451 x+87.281(R2 =0.705,P<0.0001),all sample sizes are N=339.