The Scion Grafting Pecan Different Physiological Response To Heat Stress

Pecan is a kind of important economic crops, the prospects for development will be veryfavorable. Temperature is one of the important factors which influence the production of plantgrowth and fruit. Therefore, this topic is chosen from pecans west and pecan/pecan （scion/stock）two grafting pecan, pecan, pecan/Hunan as the material, under control of36℃（intermediate hightemperature）,41℃（high temperature） and30℃（compare） respectively with4days then determinethe gas exchange parameters, fluorescence, protective enzyme activity, and the change ofmalonaldehyde（MDA） and chlorophyll content of Pecan leaf. Preliminary research thephysiological and biochemical changes under high temperature stress of different scion graftingpecan, which would expanding the pecan cultivation area and provides some theoretical basis forindustrialization of pecans. Results show that in the first3days, the activities of superoxidedismutase （SOD）, catalase （CAT）, peroxidase （POD） and ascorbic acid peroxidase （ASA-POD） allrise in different levels under high temperature stress of the three varieties, reach the peak in thethird day, and in the fourth days, it began to decline or smooth. Hunan’s gain of activity of thesefour kinds enzyme were greater than others in the first three days3days, the decreasing amplitudeof enzyme activity were smaller than others on the fourth day. There are no significant decline ofchlorophyll content under high temperature stress in the first3days, and it begin to a small degreeof decline in the fourth day, the decreasing amplitude of Hunan anvil grafting pecan declines weresmaller than another two kinds. The content of MDA showed a trend of increasing in the first fourdays of high temperature stress, Hunan anvil grafting pecan’s increasing amplitude is smaller thananother two kinds. The net photosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO₂concentration （Ci）, maximum quantum efficiency of PSII （Fv/Fm） and photochemical quenching（qP）, electron transport rate （ETR） and photochemical efficiency （Φ PSII） were all decreased withthe increase of stress time and stress temperature of three kinds of pecan, Hunan anvil graftingpecan’s decreasing amplitude were less than the health nuts and local anvil grafting pecan. Theseresults show that the pecan take Hunan pecans for scion has a significant resistance ability of hightemperature stress than the anvil grafting pecan and its seedling.