Evaluation On Genetic Diversity Of Agronomic Characters And Core Collection Construction In Ziziphus Jujuba Mill.

As a native plant and the leading dry fruit, Chinese jujube (Ziziphus jujuba Mill.) had a large quantity of germpalsms. Germpalsm evaluation may provide basis for their further development and utilizatiion. Two hundred and forty eight kinds of germplasm growing in National Repository of Chinese Jujube, Pomology Institute of Shanxi Academy of Agricultural Science were employed to evaluate the genetic diversity of agronomic characters in Chinese jujube. Both qualitative characters were graded based on the distribution analysis and a model was selected for each grade. Correlation analysis and main component analysis of the quantitative characters were conducted. Core collection of 170 germplams was established based on clustering by using DPS software. Internet Information System for Chinese Jujube Germplasms was constructed basiclly. The main results were as follows:1. Variations of quantitative characters were analyzed which showed that short thorn length, fruits per bearing branch, ratio of kernel ranked the top three with variation coefficients of 1.42, 1.00 and 0.92 respectively, while ratio of edibility, growing days and flower diameter ranked the lowest three with variation coefficients of 0.02, 0.05 and 0.09 respectively.2. K-S test was conducted based on the distribution of 23 quantitative characters and it showed that extension shoot length, extension shoot diameter, internode length of extension shoots, secondary branch length, internode numbers of secondary branch, bearing branch length, leaf number per beraing branch, vertical length of leaves, Cross length of leaf, leave shape index, bearing branch number per mother branch, flower diameter, flower number per inflorescence, growing days, ratio of edibility, soluble sugar content, titrable acidity content, Vc content et. al conformed to normal distribution while short thorn length, fruit weight, fruits per bearing branch, years before fruiting and ratio of kernel failed to conform to normal distribution. The distribution characteristics of extension shoot diameter, vertical length of leaves, Cross length of leaf, leave shape index, bearing branch number per mother branch, short thorn length, ratio of kernel, flower number per inflorescence, growing days, years before fruiting and flower diameter were firstly reported.3. Probability grading of eighteen quantitative characters conformed to normal distribution were carried out. The occurrence probability of 1～5 grade was 10%,20%,40%,20% and 10% respectively and the referenced cultivars of each grade were selected for the first time.4. The classification methods of leave shape and fruit stone shape were improved. Leave shape was classified by combining leave index with location of the largest Cross length of the leave. And, stone shape was classified by combining stone index with location of the largest Cross length of the stone.5. Nineteen qualitive characters were firstly analyzed. The percentage of each group was statisticed and referenced cultivars were selected for each group.6. Correlations between quantitative characters were analyzed and correlation coefficients were tested. Significant correlations (0.01 level) were found between extension shoot length and extension shoot diameter, extension shoot diameter and secondary branch length, extension shoot diameter and growing days, vertical length of leaves and Cross length of leaf with correlation coefficients above 0.5.7. Main component analysis of 23 quantitative characters was firstly conducted and it showed that the top nine components explained 72.367% information. In terms of contribution of the characters, extension shoot length, extension shoot diameter, extension days, secondary branch length, titrable acidity content, Vc content, flower number per inflorescence, ratio of edibility, bearing branch length, flower diameter, ratio of kernel, short thorn length, years before fruiting, leave shape index and bearing branch number per mother branch showed the difference between cultivars better than the other quantitative characters.8. Euclidean distances between 170 cultivars based on 15 quantitative characters and 11 qualitative characters were analyzed. Cultiva 'Cangxianchangxiaozao' and 'Xianxianyuanxiaozao' showed smallest euclidean distance of 2.949 while 'Linfenzhenhulu' and 'Qiyangkangtouzao' showed biggest euclidean distance of 14.348. The average euclidean distance was 7.102. Average euclidean distance among provinces was a little bit higher than that inside provinces.9. One hundred and seventy cultivars were clustered by using Ward's method and Flexible UPGMA method. Jujube cultivars were divided into 12 groups when choosingλ=14.5 by Ward's method. While those cultivars were divided into 11 groups whenλ=10.4 by FUPGMA method. The clustering results by using two methods are consistent largely.10. Eight core primary collections were established combined clustering methods of Ward's and FUPGMA with sampled ratio of 10%, 20%, 30% and 40% respectively. Conformity of means, standard deviations, ranges of quantitative characters between core collections and original germplasms were studied and ratios of reserving phenotypes were compared. The results showed that core collection established combining clustering method of Ward's and sampled ratio of 20%, preserved 90.8% genetic background. Some other 6 special cultivers such as the unique triploid 'Zanhuangdazao', 'Chahuzao' with fruits shaped teapot-shape fruits et al.were added into the core collection. Finally, the core collection including 39 cultivars with reserving phenotypes ratio of 100% was established.11. Internet Information System for Chinese Jujube Germplasms was basiclly constructed on the basis of this study and 700 records in Jujube Division of Chinese Pomology Record. It provided many functions such as germplasm skiming, germplasm searching, etc.