| Alfalfa（Medicago sativa L.）has the title of"king of pasture".Due to the shortage of cultivated land resources in China,to ensure the safety of the food production.It is impossible using the limited land resources to grow grass for stockbreeding in large-scale.It is an important way to support artificial grassland animal husbandry development using the saline-alkaline soil as the important reserve land.Especially in the west of Jilin province,the development of artificial grassland is very important for the development of the northeast economy and the development of animal husbandry.In this experiment,the physiological indicators of alkaline resistance in 21 alfalfa varieties were systematically evaluated by simulating alkaline stress in hydroponics simulation.Measuring the fresh weight,dry weight,plant height,the longest root length,withering rate,proline and soluble sugar contents,superoxide dismutase（SOD）,peroxidase（POD）and ascorbic acid peroxidase（APX）and catalase（CAT）activity,malondialdehyde（MDA）content,membrane injury（MI）,soluble Na+,K+,chlorophyll a,chlorophyll b and total chlorophyll content under control and alkaline stress.The comprehensive evaluation was carried out using alkaline resistance coefficient by principal component analysis and membership function method.The alkaline resistance of alfalfa varieties was ranked as follows:Victoria>Bingchi>WL525>Gold Queen>Emperor>Salt-tolerant Star>Aohan>Optimus>Gannong NO.3>Mateway>Gongnong NO.1>Ladino>Aribou>Power 5010>WL366>Dryland>Vinal>Gibraltar>Algonquin>Gannong NO.2>Aurora.The alkaline tolerance of 21 alfalfa varieties were divided into four grades by cluster analysis.1)alkaline tolerance alfalfa:Victoria,Bingchi,WL525,Gold Queen and Emperor,2)medium-alkaline tolerance alfalfa:Salt-tolerant Star,Aohan,Optimus,Gongnong NO.3,Mateway and Gongnong NO.1,3)weak-alkaline tolerance alfalfa:Ladino,Aribou,Power 5010,WL366 and Dryland,4)alkaline sensitive alfalfa:Vinal,Gibraltar,Algonquin,Gannong NO.2 and Aurora.Plant can acquire enhanced resistantce to future stress exposure after experiencing a biotic and abitotic stress,the physiological effect in which plants are able to faster or better activate defense responses,this is known as Priming.This study found that exogenous silicon priming enhanced alkaline resistance,prevented alfalfa lodging and wilting under alkaline stress,improved its fresh weight and dry weight,total root surface area,root diameter,root volume,SOD,POD,CAT and APX activity,the net photosynthetic rate,transpiration rate and water use efficiency.At the same time,silicon induced a significant increase in resistance Na content in root,and reduced Na content in stem and leaf,reduced the transferring of Na from the root the aboveground.At the same time,increased the K content of the aboveground and underground,maintained K/Na ratio in the normal range,and then improved the alkaline resistance.Above all,the exogenous silicon has a strong priming effect on the adapting of alkaline stress environment,it could provide a new technical solution for the improving the alkaline tolerance of alfalfa. |
