| Olive(Olea europaea L.) is a world famous woody oil plants and fruit trees, cultivars had higher edible value, rich in high quality edible oil, it is called olive oil. Most studies of domestic olive involves planting seedlings of their pre-treatment and cutting propagation, aspects of its morphological variation and physiological and biochemical research under stress conditions is still few, resistance screening studies of olive varieties has not been reported in recent years. The cold and dry climate condition are the main limitation of the tree species distribution and growth factors in North China, especially in northwest area.Wudu district is the largest base of olive oil product and olive planting has formed a larger scale. Olive seedlings of Fu Jiang plantations in Longnan were be as test materials in this study. Six varieties of olive seedlings were selected to study on the cold resistance, six olive varieties are: Frantoio, Pendolino, Leccino, Ascolano Tenera, Ezhi 8, Picholine. Artificial low temperature stress and outdoor natural low temperature treatment were treated on six olive seedlings, also measured 9 physiological indexes of cold resistance and cold resistance of the 6 olive varieties were maked comprehensive evaluation, the results are as follows:(1) The results under artificial low temperature stressAfter low temperature treatment at 5℃, 0℃,-5℃ and-10℃, the relative conductivity of six olive leaf showed "S" curve with the treatment temperature decreased, combined with Logistic equation got the semi lethal temperature of different varieties of olive, in the order: Picholine(-6.687℃)﹥Pendolino(-6.303℃)﹥Leccino(-5.940℃)﹥Ascolano Tenera(-5.824℃)﹥Ezhi 8(-4.187℃)﹥Frantoio(-3.706℃). The content of chlorophyll decreased with the temperature decreasing, the content of soluble sugar increased as the temperature decreased, the content of soluble protein, proline content, MDA content, SOD activity, POD activity and CAT activity was increased first and then decreased as the temperature decreased.Comprehensive evaluation of cold resistance by using principal component and membership function evaluation was consistent, variety screening results as: Picholine(0.613)﹥Pendolino(0.597)﹥Leccino(0.516)﹥Ascolano Tenera(0.507)﹥Ezhi 8(0.313)﹥Frantoio(0.281).The order of the grey correlation between cold resistance indexes and cold resistance was: superoxide dismutase(SOD)>soluble protein(SP)>catalase(CAT)>chlorophyll(Chl)>peroxidase(POD)>proline(Pro)>relative conductivity(REC)>soluble sugar(SS)>malondialdehyde(MDA).(2) The results under natural low temperature stressSampling time under the condition of natural cooling was: September 15, 2013, October 15, 2013, November 14, 2013, December 14, 2013 and January 13, 2014. Research results were: the relative conductivity of six olive increased in linearly change with the treatment temperature decreased, combined with Logistic equation got the semi lethal temperature of different varieties of olive, followed by: Picholine(-8.937℃)﹥Pendolino(-8.158℃)﹥Ascolano Tenera(-5.628℃)﹥Frantoio(-4.459℃)﹥Leccino(-4.293℃)﹥Ezhi 8(-4.183℃). The content of chlorophyll decreased with the temperature decreasing, the content of soluble sugar, soluble protein content, proline content, MDA content, SOD activity and CAT activity showed a linear upward trend, POD activity showed a trend of first increased then decreased and then increased again.The screening results of cold hardiness comprehensive evaluation by principal component analysis was: Picholine(2.014)>Pendolino(0.639)>Leccino(-0.209)>Ascolano Tenera(-0.627)>Ezhi 8(-0.722)>Frantoio(-1.096), and the result of cold resistance comprehensive evaluation by using membership function was: Pendolino(0.519)﹥Picholine(0.499)﹥Ascolano Tenera(0.448)﹥Leccino(0.417)﹥Ezhi 8(0.378)﹥Frantoio(0.331).The order of the grey correlation between cold resistance indexes and cold resistance was: soluble protein(SP)>peroxidase(POD)>catalase(CAT)>soluble sugar(SS)>chlorophyll(Chl)>superoxide dismutase(SOD)>proline(Pro)>relative conductivity(REC)>malondialdehyde(MDA). |
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