Screening And Comprehensive Evaluation Of Alfalfa Varieties In Yangzhou

Alfalfa is the high-quality roughage for dairy farming,and East China has long relied on imported alfalfa hay for its needs.In order to select high-quality alfalfa(Medicago sativa)varieties suitable for cultivation in Yangzhou,22 foreign introduced alfalfa varieties were used as test materials from autumn 2021 to summer 2022 to investigate plant growth characteristics(fertility period,growth rate,plant height,main stem thickness,main stem node spacing,main stem node length,leaf length,leaf width,leaf number),economic quality characteristics(plant height,hay yield,fresh to dry ratio,stem to leaf ratio,regeneration,DM,CP,EE,Ash,NDF,ADF,Ca,P,RFV),photosynthetic characteristics(Pn,Gs,Ci,Tr,Ls,LUE,WUE),and a comprehensive evaluation by grey correlation analysis to select varieties with strong adaptability,high growth potential,high yield,good palatability,nutrient-rich and photosynthetic capacity,The alfalfa varieties with high adaptability,growth potential,high yield,good palatability,nutrient-rich and photosynthetic ability were finally selected for promotion in Yangzhou area.The main findings of the study are as follows:(1)The 22 alfalfa varieties tested had a fertility period of 204-214 days and all overwintered and summered safely.The non-fallow variety Claudia was the earliest to return to growth on 16 February 2022,while the lower the fallow level the later the variety returned to growth.Plant height varied significantly(P<0.05)throughout the reproductive period,with a "slow-fast-slow" growth mechanism.Main stem node length was strongly correlated with alfalfa plant height(P<0.05)and was positively correlated with main stem thickness,but was highly significantly negatively correlated with main stem node number.Leaf length and width as well as the number of leaves varied significantly between alfalfa varieties,with leaf length and leaf width reaching a significant correlation(P<0.05)and leaf length also positively correlating with the number of leaves.(2)The plant height of the three alfalfa crops in the trial showed that the first crop>second crop>third crop.The three hay crops accounted for 37%,35%and 28%of the total yield respectively;the highest total hay yield of 37101 kg/hm2 was achieved by the Tianma variety.the regeneration rate of alfalfa was second crop>third crop>first crop.Victoria had the lowest fresh-to-dry ratio;the lowest stem-to-leaf ratio was for Cattleya.Cluster analysis was used to classify the nutritional quality of alfalfa,with Avia and WL168HQ having higher yields and better quality with higher crude protein and mineral content and lower lignin content.(3)The net photosynthetic rate,stomatal conductance,intercellular CO2 concentration,transpiration rate,stomatal limitation,light energy utilisation and water utilisation of the tested alfalfa varieties were significantly different(P<0.05).Transpiration rate,stomatal conductance and light energy utilisation were highly significantly correlated with alfalfa yield(P<0.01),but intercellular CO2 concentration and transpiration rate were negatively correlated with yield.Cluster analysis revealed that the best photosynthetic characteristics were found in Aviary and Tianma alfalfa.(4)Applying grey correlation analysis,it was concluded that the five alfalfa varieties,Tianma,Avia,WL168HQ,Claudia and Greensilk,had excellent overall performance and were most suitable for growing in the Yangzhou area.