Effects Of Exogenous Spraying Brassinolide On Cold Resistance Of ’Merlot’ Grape

Low temperature is a kind of abiotic stress in the process of plant growth,which affects each stage of plant growth and the yield and quality of plants.Low temperature has become the main obstacle restricting the growth stage of plants.Using various techniques to enhance plant frost resistance has become a research hotspot in the world.The in-depth discussion on the low temperature adaptability of plants has not only a certain scientific theoretical significance,but also a great practical value.Especially in the mountainous area of eastern Helan Mountain,the problem of cold tolerance of grape varieties sensitive to low temperature is becoming more and more prominent.Merlot grapes(Vitis vinifera L.cv.Merlot)are early-ripening,fresh and high yielding.It is a very good wine grape and has become one of the fine varieties of red wine in my country.Merlot is suitable for sandy cultivation,likes warm climate,and is very sensitive to low temperature.Brassinolide(2,4-Epibrassinolide,EBR)is a non-toxic and efficient plant hormone,which has strong stress resistance.In this study,’Merlot’ grape seedlings were used as the research object,and the whole plant was sprayed with 0.4 mg/L EBR in a programmed cooling method at different low temperatures(4℃,0℃,-2℃).The mechanism of EBR’s low-temperature adaptive regulation of ’Merlot’ grapes was systematically studied,in order to provide a new theoretical basis for EBR’s low-temperature adaptive regulation of plants,and to lay a solid foundation for further research on its cold tolerance.The research results and conclusions of this paper are as follows:1.Low temperature stress affects the growth of ’Merlot’ grape seedlings.Exogenous spraying of EBR can not only increase the plant height,base diameter,number of leaves,and leaf area of ’Merlot’grape seedlings,but also can improve ’Merlot’ grape seedlings.Root length,root surface area,root volume,and number of root of seedlings.It shows that EBR can increase the growth of grape seedlings,alleviate the damage to seedlings caused by low temperature,and enhance the cold resistance of ’Merlot’grapes.2.Under low temperature stress,spraying EBR could increase SOD,POD,CAT activities,AsA and GSH contents,accumulation of Pro and soluble sugar,and decrease the accumulation of malondialdehyde(MDA)and electrical conductivity in leaves of ’Merlot’ grape.It indicated that EBR could increase the activity of antioxidant enzymes and antioxidant substances in grape leaves,reduce cell membrane permeability damage and electrolyte extravasation to maintain the balance of leaf growth and metabolism,and reduce the damage of low temperature to grape leaves.3.Under low temperature stress,spraying EBR could improve the root vigor and root soluble sugar content of ’Merlot’ grapes,relieve the damage of low temperature to grape roots to a certain extent,and promote the growth of grape seedlings.4.Under low temperature stress,the cold resistance of grape leaves can be improved by reducing the electrical conductivity and MDA content of grape leaves.On the other hand,the cold resistance of grape leaves can be improved by increasing CAT activity,GSH content,soluble sugar content and proline content in grape leaves.In conclusion,EBR treatment can increase the activity of protective enzymes,antioxidant substances and osmotic regulators in ’Merlot’ grape leaves under low temperature stress,reduce cell membrane permeability damage and electrolyte extravasation to maintain the balance of leaf growth and metabolism,and alleviate its growth inhibition.,thereby promoting the growth of grape seedlings and roots,enhancing the root vitality of grapes,and accumulating soluble sugar in the roots,thereby improving the cold resistance of grape seedlings and promoting the growth of grape seedlings.