| Analyses of leaf venation traits of cultivated and wild jujubes in hilly region of Loess Plateau |
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| DOI：10.7606/j.issn.1000-7601.2019.06.05 |
| Key Words: leaf venation wild jujube cultivated jujube characteristic index hilly region on Loess Plateau |
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| Abstract: |
| To further understand the relationship between leaf venation traits and diversities of cultivated and wild jujubes, a total of 90 jujube accessions were collected in hilly jujube region on Loess Plateau, including 55 cultivated jujube (Ziziphus jujube Mill.), 28 indigenous wild jujube (Z. jujuba var. spinosa), and 7 transitional accessions. These accessions had been analyzed for their leaf venation traits with 14 parameters of leaf vein and areole through the software of LEAF GUI. Eight characteristic indexes suitable for studying the venation of jujube leaves were screened out using principal component analysis, and the characteristics of leaf venation and differences of the cultivated jujube, wild jujube, and transitional accessions were analyzed. The results showed that wild jujube growing in arid and barren habitats had significantly higher values of VLA (7.14 mm·mm-2); significantly lower values of vein distance (0.094 mm), areole area (2.84×10-4mm2), number of node (17 823) than cultivated jujubes in jujube garden in hilly region of Loess Plateau. This indicated that wild jujubes had stronger ecological adaptability. Meanwhile, the variation coefficient range of jujube leaf venation (15.24%~74.69%) was wider than that of wild jujube (20.37%~52.84%). Hence, cultivated and wild jujubes could take different adaptation strategies after judging the relationships among leaf venation characteristics. Compared with jujube, wild jujube was inclined to choose adaptive strategies with high vein density, low areole area, and low nodes. Dengrogram of neighbor\|joining clustering analysis of jujube accessions sampled in northern Shaanxi showed that when the similarity coefficient between the two major clusters, I and II, was 1.8, but for jujube accessions sampled in Hilly Region of Loess Plateau it was 1.69. The clusters I and II was designated as wild and cultivated jujube groups, respectively. The transitional type appeared in both clusters I and II. Therefore, the evolution of wild jujube through transitional type to cultivated jujube was further explained. It also indicated that leaf venation can be used as an important index to divide cultivated and wild jujube. In addition, the results of UPGMA cluster analysis of vein features and quantitative traits of terminal venation network of cultivated jujubes showed that cultivated jujube can be grouped into four major clusters with similarity coefficient of 1.29. The complex interspecific structure of cultivated jujubes was determined by strong artificial selection and vegetative propagation. |
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