| The relationship of Mengshancui jujube with 9 Chinese jujube (Ziziphus jujuba Mill.) varieties and 32 wild jujube (Z. acidojujua C.Y.Cheng et M.J.Liu) types from Shandong province were studied by morphological characteristics analysis and random amplified polymorphic DNA (RAPD) analysis. The origin of Mengshancui jujube and the evolution of jujube were also discussed. Two-year-old jujube varieties Mengshancui and Zhanhuadong were used as material to study drought resistant physiology of Mengshancui jujube in concern of the following indexes such as leaves relative water content (LRWC), chlorophyll content, stomatal conductance (Gs), transpiration rate (Tr), net photosynthetic rate (Pn), water use efficiency (WUE), proline content, betaine content, SOD activity, POD activity, leaf water retention and permanent wilting coefficient. And drought resistances of two jujube varieties were also compared. The main results were as followings:1. The principal components analysis based on morphological characteristics data indicated that the first principal components value of Mengshancui jujube was 5.42, the second principal components value was 0.64 which were in the middle of Chinese jujube and wild jujube varieties (types) and showed special classification position. The cluster analysis results of morphological characteristics that Mengshancui jujube and No.1 of wild jujube were first clustered together at 6.40 threshold, second with Chinese jujube varieties at 11.75 threshold, then with other wild jujube varieties (types), indicated that Mengshancui jujube was the middle varieties between wild jujube and Chinese jujube varieties. 2. 20 primers that can amplify stably were used for RAPD and cluster analysis of 8 jujube varieties. The results indicated that 8 jujube varieties can be classified into 4 categories. Mengshancui jujube had closer relationship with wild jujube and was the middle varieties between wild jujube and Chinese jujube varieties.3. The morphological characteristics of Mengshancui jujube was closer with Chinese jujube, its fruit was about 2cm long with flimsy exocarp and thick mesocarp, the mean individual fruit weight was 3.64g, and leaf longitudinal and traverse diameter was 6.93cm×3.08cm, its Vc content was higher than Jujube varieties and lower than wild jujube varieties (types). Then Mengshancui jujube was confered to the middle type between wild jujube and Chinese jujube.4. The physiological and biochemical indexes closely correlated with drought resistant physiology were studied. The results showed that: under water-stress, LRWC, chlorophyll content, Gs, Tr and Pn were declined along with the decrease of water stress, but WUE, proline content and betaine content showing ringing tendency. SOD and POD activity was increased first and then decreased. The drought resistance of Mengshancui was higher than Zhanhuadong.5. The farther correlation and path analysis of physiological and biochemical indexes indicated that, there was a significant correlation between betaine and proline content, but they were negatively correlated to LRWC. The high betaine and proline content were very important to leaf keep higher LRWC, SOD activity was negatively correlated to LRWC and had effect to leaf keep higher LRWC. POD activity had little effect to leaf keeping higher LRWC, and its main function is to scavenge H2O2 during water-stress. 6. When soil water content of Mengshancui and Zhanhuadong both lower than 6%, the LRWC of two jujube varieties both can keep higher than 80% yet. Permanent wilting coefficient of Mengshancui and Zhanhuadong were 2.162% and 2.997% respectively, both lower than 3% and lower than other trees, which indicated that jujube has higher drought hardiness.7. Plant genotype was closely related to its drought resistance abilities. Mengshancui jujube was the middle type between wild jujube and Chinese jujube, its drought resistance abilities and yields in Mengyin were higher than other varieties. Fruit of Mengshancui jujube has high Vc content, strong lavour and full kernel, wh... |
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