Evaluation On Adaptability And Production Performance Of 3 Cold Resistance Strains Of Alfalfa In Gannan Cold Area

To breed high yield and quality variety of Medicago sativa. L that are suitable to plant in cold humid climate zone, and provide theoretical basis for extensive promotion and the utilization of high quality alfalfa germplasm resources, a planting experiment were conducted on 3 cold-resistant strains bred in Gansu Agricultural University, college of Grassland Science: GNKH-1(Medicago sativa L. cv.kanghan No.1)、GNKH-2(M. sativa L.cv.kanghan No.2) and GNKH-3(M. sativa L. cv.kanghan No.3) during two continuous years in northeast edge of Qinghai-Tibet Plateau subalpine cold humid climate plot(Xiahe County Gannan Prefecture). M. sativa L.subsp varia(fall dormancy grade:2), M. sativa L.cv.Golden Empress(fall dormancy grade:2)and M. sativa.L cv.Algonguin(fall dormancy grade:3)were control materials, and warm semi-arid climate zone(Gansu agricultural university, Lanzhou forage experimental station) was reference plot. The production performance, nutritive value, the content of amino acid, protein quality and cold-resistant physiological adaptability were comprehensively evaluated by using PCA( principal component analysis), subordinate function, grey incidence degree model, AAS and EAAI. Genetic differences of tested alfalfa materials were analyzed by ISSR molecular markers. The results show:Based on cold-resistant physiological indexes: wintering rate, the content of proline, soluble sugar, soluble protein and MDA, cold-resistant physiological adaptability of tested materials were comprehensively evaluated by using subordinate function value analysis in cold humid climate zone.The adaptability priority was GNKH-1>GNKH-3>M. sativa L.subsp varia>GNKH-2>M. sativa.L cv.Algonguin>M. sativa L.cv.Golden Empress.The comprehensive evaluation of production performance was performed on indexes such as hay yield, plant height, growth rate, branch number and so on by PCA. PCA comprehensive priority of each alflafa material in cold humid climate zone was GNKH-3>GNKH-2>GNKH-1>M. sativa.L cv.Algonguin>M. sativa L.subsp varia>M. sativa L.cv.Golden Empress. The production performance of GNKH-3 was the best in cold humid climate zone, while that of GNKH-2 and GNKH-1 were the second excellent.Based on 8 nutrient quality indexes: crude protein, crude fat, crude ash, acid detergent fiber, neutral detergent fiber, leaf-stem ratio, nitrogen free extract and relative feed value, the grey incidence degree model was used to comprehensively evaluate the nutrient value of tested alfalfa materials in cold humid climate zone.The nutrient quality priority was GNKH-3>GNKH-2>M. sativa L.subsp varia>GNKH-1>M. sativa.L cv.Algonguin>M. sativa L.cv.Golden Empress.The protein quality in leaf and stem of alfalfa materials were evaluated by using AAS and EAAI in cold humid climate zone. Protein quality priority in leaf was M. sativa L.cv.Golden Empress>GNKH-1>GNKH-3>GNKH-2>M. sativa.L cv.Algonguin>M. sativa L.subsp varia and that in stem was M. sativa L.cv.Golden Empress>GNKH-1>GNKH-2>GNKH-3>M. sativa L.subsp varia>M. sativa.L cv.Algonguin. The AAS of GNKH-3 in leaf was the highest(327.43%) and 29.24% higher than that of GNKH-1(AAS = 298.14%), which was the lowest in cold humid climate zones; The AAS of GNKH-3 in stem was 159.39%, and 19.58%, 25.66% 0.43% and 5.94% higher than that of GNKH-1(AAS=128.19%), GNKH-2(AAS=118.49%), M. sativa L.subsp varia,(AAS=158.70%)and M. sativa.L cv.Algonguin(AAS=149.92%), respectively. The EAAI of M. sativa.L cv.Algonguin(1.2860) and GNKH-1(1.2847) in leaf were the highest, while that of M. sativa L.subsp varia,( 1.2881) and M. sativa.L cv.Algonguin(1.2876) in stem were the highest.The 6 tested alfalfa materials were assigned into 2 clusters at the genetic distance of 0.78 by 8 ISSR primers. Cluster 1 comprised of 3 cold-resistant strains: GNKH-1, GNKH-2 and GNKH-3, and featured with high yield, high nutritional value, good protein quality, and strong adaptability to cold; Cluster 2 comprised of 3 contrast materials: M. sativa L.subsp varia, M. sativa L.cv.Golden Empress and M. sativa.L cv.Algonguin, with production, cold adaptability and nutritional value relatively lower than cluster 1.In conclusion, GNKH-3 was the most optimum variety in northeast edge of Qinghai-Tibet Plateau subalpine cold humid climate.(1)With the earliest period of seedling establishment, GNKH-3 performed the best in production indicators such as forage yield, plant height, internode number, internode length, growth rate and branch number.(2)GNKHhad the highest wintering rate and soluble protein content, relative high content of proline and soluble sugar and low content of MDA.(3)Its performance in crude protein, nitrogen free extract, leaf-stem ratio were the best, that in crude fat, crude ash, relative feeding value index were better and relative contents of ADF and NDF were low.(4)With total amino acids and essential amino acid content in leaf rank only second to GNKH-2, GNKH-3 had a relative high AAS and its EAAI in leaf and stem were more than 0.95, which indicates that it was a source of high quality protein.(5)The ISSR analysis showed that polymorphism of amplification products was informative, with the rate all excelled 80%. The genetic similarity coefficient of 6 alfalfa materials ranged from 0.4828 to 0.9540. GNKH-1 and GNKH-2 were the most similar in genetics(0.9540), while GNKH-3 and M. sativa.L cv.Algonguin were the least similar(0.4828). The genetic similarity coefficient between GNKH-1 and parent M. sativa.L cv.Algonguin was 0.5172, and that between GNKH-3 and parent M. sativa L.cv.Golden Empress was 0.5517. The 6 tested alfalfa materials were divided into 5 clusters at the genetic distance of 0.90. GNKH-1 and GNKH-2 made up cluster 1, cluster 2, 3, 4 and 5 was GNKH-3, M. sativa L.subsp varia, M. sativa L.cv.Golden Empress and M. sativa.L cv.Algonguin, respectively. The adaptation of GNKH-1 and GNKH-2 in cold humid climate zone was only second to GNKH- 3.