Study On The Correlation Between Physiological Index Of Shoots And Leaves Of Almond And Its Cold-Resistance

Almond, Amygdalus communis L., is one of the four most important nuts in the world. It is not only a fine species producing nuts, but also a woody oil plant and a species beneficial to water conservation. Because it brings together the nutritive value, economic value and ecological value, it draws more and more attention. China is a native country of almond production, with a long cultivation history and abundant resources. Yet very few large-scale almond orchards can be seen in China. In northern China, many varieties introduced from outside just bloom yet without any fruits. Especially in early spring, these varieties often suffer from late-frost damage if the temperature is too low. Therefore, study on cold resistance of different almond varieties plays a very important role in the selection of cold-resistant cultivars as well as in their popularization in the whole country.The cold-resistant cultivar, Yengisar, from Xinjiang was taken as the CK in this research, and Jinbian No.1 and No.2 were taken as the test materials. The relative conductivity and the changing rule of each physiological index during the overwintering process and the artificial treatment under low temperatures were studied. The results were as follows:1. During the overwintering process, the changing rule for each physiological index of the three cultivars was different. Yengisar had the highest content of soluble sugar, soluble proteins and free proline. It also had the highest activity of POD and SOD. Yet the MDA content was lowest in Yenggisar. The content of each index in Jinbian No.2 was contrary to that of Yenggisar. And Jinbian No.1 had middle levels for the content of each index.2. During the treatment of artificial temperature-dropping, the relative conductivity for the leaves of the three cultivars increased with the continuous dropping of the temperature. And it showed a regular changing, which was slow-rapid-slow, displaying an "S" curve. Fitting the Logistic equation, the semi-lethal temperatures for the leaves of the three cultivars were found out, which were-8.9618℃,-7.359℃and-9.7364℃for Jinbian No.1, Jinbian No.2 and Yenggisar respectively. This result was in accordance with the investigation in the field. So the cold-resistance of the three cultivars could be tentatively determined. The strongest was Yenggisar, followed by Jinbian No.1 and Jinbian No.2 respectively.3. During the treatment of artificial temperature-dropping, the variation trend for the same physiological index of leaves and branches of the three cultivars was almost the same. Yengisar had the highest content of soluble sugar, soluble proteins and free proline, the highest activity of POD and SOD, while the lowest relative conductivity and MDA content. Jinbian No.2 had the highest relative conductivity and MDA content, yet the lowest content for other indexes. Jinbian No.1 had middle levels for the content of each index.4. The results after comprehensive analysis showed that the content of soluble sugar, soluble proteins and free proline, as well as the activity of POD and SOD was positively correlated with the cold-resistance of almond, while the relative conductivity and MDA content were negatively correlated.5. The order for the cold resistance of the three cultivars from stronger to weaker was Yenggisar, Jinbian No.1 and Jinbian No.2.