| At present, the yield and quality of alfalfa hey are low, and the number of improved varieties is not rich. The same reason,it is far from adequate to meet the needs of alfalfa production. So, there is an urgent need to strengthen alfalfa germplasm research and utilization, speed up the breeding of superior varieties, improving yield and quality of alfalfa, so as to meet the needs of the market. Some study suggests that multifoliate alfalfa has the potential to improve the yield and quality, but there is highly controversial on if the multifoliate alfalfa has the ability to increase yield and photosynthetic efficiency.(1) Firstly, this study spent a two-year field experiment on alfalfa forage yield-related traits and genetic diversity analysis; and study the relationship between stem/leaf ratio and yield-related traits by correlation analysis, then multifoliate alfalfa genetic diversity can be done by SSR molecular marker methods.(2) This study analyse the trait expression characteristics of multifoliate alfalfa through field investigation;besides,the relationship between Compound leaf area, stem/leaf ratio, leafy rate and leaf area were also analysed.(3) Using a photosynthetic apparatus to study photosynthetic efficiency of multifoliate alfalfa and three-leaf alfalfa, on this basis, photosynthetic apparatus and chloroplast ultra-structure can be used to study the photosynthetic efficiency in different types of compound leaves of alfalfa.(4) Using scanning electron microscopic to study the apical meristem development characteristics of multifoliate alfalfa,and compared the morphogenesis of compound leaves and the development characteristics of flowers of multifoliate alfalfa and three-leaf alfalfa.(5) Study on anther culture of multifoliate alfalfa, filtering the best medium for anther culture of multifoliate alfalfa, doing identification of the ploidys of regenerated plants from anther culture.This article’s main findings are as follows:(1) The average hay yield of multifoliate alfalfa WL323in two years is the highest,19551.45kg/hm2; the average hay yield of8920MF and Phabulous is15395.23kg/hm2and15245.64kg/hm2, at a high level in all participants, better than Super7, AmeriStand. GL0601and AmeriGraze. All stem/leaf ratio of multifoliate alfalfa in every stubble are higher than three-leaf alfalfa. Leaf-stem ratio of alfalfa has a positive correlation with hey yield.but significant negative correlation with branches and section number. SSR analysis of genetic diversity found that alfalfa materials with leafy traits are in the close genetic relationship,can be separately gathered as one.(2) In the main stem of multifoliate alfalfa, type of4+5compound leaves is the most, the average of each material is about13.06%; type of4compound leaves is the least, the average of each material is about0.01%; the more4+5compound leaves, the higher leafy rate; WL343HQ has the highest leafy rate,25.71%, and its’ leafy rate of4+5compound leaves is13.88%.Each compound leaves’ leaf area of multifoliate alfalfa is larger than the control of huaiyin; compound leaves’ leaf area of multifoliate alfalfa is between8.65cm2and9.10cm2,the control material, huaiyin,is only6.22cm2.By the correlation analysis of leafy rate, leaf area and stem/leaf ratio, this study found that leafy rate had a positive correlation with stem/leaf ratio, the higher leafy rate, the higher stem/leaf ratio; as well as stem/leaf ratio, leafy rate also had a significantly positively correlation with leaf area, the higher leafy rate, the larger leaf area; Leaf area and stem/leaf ratio are related, but not significantly.(3) This study did the analysis of photosynthetic parameters of multifoliate alfalfa and three-leaf alfalfa,found that the average Pn of multifoliate alfalfa was about25.79μmol·m-2·s-1, photosynthetic efficiency was significantly greater than three-leaf alfalfa. In different types of compound leaf photosynthetic efficiency, the Pn of5-leaf leaflet was the max, the order of the Pn was quinquefoliolate alfalfa> quadrifoliate leaflets> trifoliate leaflets> six leaves type seven leaves type> eight leaves type> Nine leaves type. In the mesophyll of quinquefoliolate alfalfa, the number of chloroplasts was the most in every cell, and with many granas in chloroplasts, stroma is thick, and the grana lamella were tight; the number of Osmophilic globule was few, starch grains in chloroplast was rich and full. Therefore, in breeding of Alfalfa leafy traits, using the quinquefoliolate alfalfa as the target can improve the photosynthetic efficiency of alfalfa.(4) This study analysed the morphogenesis of3and5type of compound leaf, then found that the model of compound leaves of alfalfa was top, the apical meristem morphology characteristics of3and5type of compound leaf wre the irregular square structure, which can be classified into7stages. Morphological characteristics of SO was similar to S1, forming the common primordial; primordia appeared in stage2, the number of those uplift was different; in S3,2side leaf primordia appeared in3type of compound leaf,4side leaf primordia appeared in5type of compound leaf, the following Morphological characteristics was the similar. It was the key stage from S2to S3,it determined the number of blades and blade life. In the study of Morphological development of alfalfa, the followings were found:flower was symmetric on both sides, as typical21-organs. Its morphological characteristics were similar to other Butterfly subfamily, with the appearing of differentiation of primary inflorescence meristem and secondary inflorescence meristem, secondary inflorescence meristem then developed into floral meristem and flower meristem developed into other organs, which also has four divisions of common primordia in the development. It was divided into8stages by the different characteristics development. it was of great significance for the study of male sterile, precise selection of anther culture of flower bud,and the molecular biology mechanism of alfalfa.(5) It was found that anther culture callus induction worked the best after15-28d of alfalfa budding. The best medium for the callus differentiation was modified Blaydes medium, that was adding inositol100mg·L-1, casein hydrolysis200mg·L-1,2-IP0.5mg·L-1, NAA0.2mg·L-1and KT1.0mg·L-1to Blaydes medium, in which condition, callus differentiation was more efficient. The induction effect of1/2B5medium was better than1/2MS. Flow Cytometry was used to Detected the regenerated plants, then,it was found that plants from anther culture had a more complicated ploidy, mixoploid and aneuploid may appear. This research had a great significance to haploid and doubled haploid breeding of alfalfa. |
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