Comparative drought tolerance of six native deciduous and broad-leaved woody plant species seedlings in the Qinghai-Tibet Plateau

Choice of native woody species with higher drought tolerance is the basic work on afforestation in Qinghai-Tibet Plateau (QTP) region. However, no systemic evaluation has been made of the drought tolerance ability. In the present study, we compared the drought injury degree and ten physiological and biochemical indices from six native deciduous and broad-leaved woody plant species seedlings under continuous drought for 21 days. The ten indices included relative water content, net photosynthetic rate, transpiration, water use efficiency, superoxide dismutase, peroxidase, catalase and malondialdehyde, proline and soluble sugars contents of leaves. Under drought stress, six native species showed the different response. According to analysis of the mean membership function values, the drought tolerance of six native species could be ranked in the following order: Berberis hemsleyana > Sophora viciifolia > Betula platyphylla > Cotoneaster rotundifolius > Prunus mira > Hippophae rhamnoides. Species B. hemsleyana and S. viciifolia were relatively high drought-tolerant, while P. mira and H. rhamnoides were relatively low tolerant. The two high-tolerant native species resist to drought by different strategies after long-term adaptation, and these two species should be given prior consideration in deciduous woody plant species selection for afforestation in arid and semi-arid area of QTP in the future.