Abstract:

In order to screen fine salt-tolerant and fast-growing Fraxinus clones, 42 Fraxinus clones collected in China were studied under coastal saline-alkaline stress. The genetic variation of dry/fresh ratio, plant height, ground diameter, superoxide dismutase (SOD), cell membrane permeability, chlorophyll, peroxidase (POD), malondialdehyde (MDA) physiological metabolism of the 42 clones were analyzed and evaluated by using the correlation and principal component analysis. The results showed that there were some differences among 8 indexes of the 42 clones. The variation coefficient of peroxidase (POD) was the largest (64.33%), and the range of variation was 25.00-458.30 U/(g·min). The variation coefficient of malondialdehyde (MDA) was the second, with a variation coefficient of 49.52% and a variation range of 0.50-7.08 μmol/kg. In terms of chlorophyll and ground diameter, the coefficient of variation was 18.92% and 18.56%, respectively, and the variation range was 1.46-4.26 mg/g and 1.15-2.78 cm, respectively. The results of correlation analysis showed that the dry/fresh ratio, plant height and ground diameter of seedlings under saline-alkaline stress were significantly or extremely and significantly correlated with various physiological indexes, indicating that the comprehensive evaluation of the salt-tolerance of Fraxinus clones by using growth indexes and physiological indexes could better reflect the response of Fraxinus clones to saline-alkaline stress in coastal areas. According to the comprehensive score and ranking of the 42 clones of Fraxinus germplasm resources by principal component analysis, the top 10 clones with saline-alkaline tolerance from strong to weak were ‘Yan 3’> ‘LC13’> ‘Ji 20’ > ‘R7-2’> ‘Yan 2’ > ‘Huancui 3’ > ‘Jiaonan 11’> ‘Baila 4-2’and ‘Baila 2’> ‘DT21’. Therefore, it is preliminarily concluded that the above 10 clones have significantly fast growth and saline-alkaline tolerance, and could be used as important materials for site afforestation or stress tolerance breeding.

Key words: Fraxinus, coastal saline-alkaline area, germplasm resources, clone, saline-alkaline tolerance, principal component analysis