Study On Drought Stress To Photosyntheyic,water Consumption Haracteristics And Drought Resistance Of Malus Domestica Borkh.CV.Red Fuji

Apple(Malus pumila Mill.) was the rose family (Rosaceae) Malus (malus) for the perennial plant.China is the largest producer and consumer of apples in the world,played an important position in the apple industry world.The loess plateau of northwes region was one of the best apple-producing areas,this region accounted for about 44%,production accounted for about 49% in china.As the loess plateau of northwest was in arid and semi arid areas,So water was the key oecological factors in this areas.Water is the main factors that limited the normal growth and development of plant,production reduction of crops caused by water stress had more than other environmental stress.Therefore,studying on drought stress to growth and development,photosynthetic water consumption and drought resistance of apple trees, has important theoretical and practical.This test used one-year old "Fuji" apple trees,rootstock was Xinjiang wild apple as material. As pot was water control test under different drought:Ck was 70%-75%;moderate water stress is 50%-55%;severe drought stress was 40-45%.Measuring the leaf area,dry weight,fresh weight and root-shoot ratio reveal growth law on apple trees. Studyed on the photosynthetic,water consumption of one-Year old apple trees using weighing method and Yaxin-1102 portable photosynthesis system. Studyed on active oxygen metabolism and osmotic adjustment matter using dehydration-rehydration treatment and drought stress treatment.This study provided a theoretical basis in arid and semi arid areas for rational use of water resources and increasing fruit yield and quality.The main conclusions were as following.(1)The leaf area,fresh weight and dry weight of Fuji apple trees sapling all decreased with the deepening of drought level,while the root-shoot ratio increased with the deepening of drought level under different drought stress,the results show that the severe drought inhibited markedly the growth and development of apple tress.(2)The daily variation curve of net photosynthetic rate presented double-peak type,the two peak time appeared in 10:00 and 16:00 respectively.Net photosynthetic rate ranked: control>moderate stress>severe stress.The daily variation curve of transpiration rate presented double-peak type,peak time appeared in 10:00 and 16:00 respectively.The daily variation curve of water use efficiency was decreasing gradually from the morning at 6:00 a.m.,lowest value appeared in 12:00 and 14:00 respectively,increased slightly after lowest value.Under three kinds of processing,the daily variation curve of water-consumption of control treatment presented single-peak type,and peak time appeared between 14:00-16:00; the daily variation curve of water-consumption of moderate water stress and severe water stress all presented double-peak type,peak time appeared between 14:00-16:00 and between 16:00-18:00 respectively.The daily variation curve of consumption rate and water consumption roughly had the same consequence.The month variation curve of water-consumption presented single-peak curve,water-consumption is increasing gradually, maximum appeared in July,water-consumption decreased gradually after August.(3)Under dehydration-rehydration treatment , the contents of MDA,H₂O₂ and O₂^-·generation rate ascended,and descended after rewatering with the strengthening of drought stress in apple leaves.The results indicated that the activity of the SOD were ascended firstly,then descended and ascended lastly,and descended after rewatering;The activity of the POD descended firstly,then ascended and descended until rewatering.The activity of APX ascended firstly,then descended until rewatering. Under drought stress treatment:the contents of MDA,H₂O₂,O₂^-·generation rate ascended gradually.the contents ranked:control> moderate water stress >severe water stress . With the increase of stress time,the results indicated that the activity of the SOD were ascended firstly, then descended.The activity of POD ascended firstly, then descended.The activity of the APX ascended under moderate water stress,and ascended firstly,then descended under severe water stress.(4)Under dehydration-rehydration treatment,proline,soluble sugar,soluble protein ascended,and descended after rewatering in apple leaves.The content of soluble protein had the maximum at the 7 day,then descended after rewatering.Under drought stress treatment, with the strengthening of drought stress the content of soluble sugar and soluble protein ascended firstly,then descended,the content of proline ascended.