关键词: 生长形态, 光合, 干旱胁迫, 叶绿素, 叶水势

Abstract: To provide theoretical support for species selection, breeding and vegetation restoration in northern Hebei Province, we assessed the ecophysiological adaptability and drought resistance of different shrub species to drought stress, including four native shrub species (Potentilla fruticosa, Artemisia ordosica, Ostryopsis davidiana, and Lespedeza bicolor) and two introduced shrub species (Hippophae rhamnoides, and Vitex negundovar. heterophylla). Four water levels (85%±5%, 70%±5%, 50%±5% and 35%±5% of field water-holding capacity, designated as T1, T2, T3 and T4, respectively) were set up for indoor pot experiment of drought stress. We measured biomass, plant height change rate, root/shoot ratio, relative chlorophyll content (SPAD value), leaf water potential, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r) and water use efficiency (WUE). The results showed that: (1) Under drought stress, the root/shoot ratio of P. fruticosa and A. ordosica significantly increased (P<0.05), and the decrease of biomass and plant height change rate was limited, while biomass and the change rate of plant height of O. davidiana and V. negundo var. heterophyllawere significantly reduced (P<0.05). (2) Under drought stress, the relative content of chlorophyll, leaf water potential and photosynthesis of all the six species decreased in different degrees, while WUE varied with the decreasing water availability. WUE of L. bicolor decreased significantly under T3 treatment (P<0.05), while H. rhamnoides and P. fruticosaincreased significantly under T3 treatment (P<0.05) and T4 treatment (P<0.05), respectively. (3) The absolute value of the load between the growth, morphology, eco-physiological and photosynthetic indices of shrubs and the main components was greater than 0.7, and the comprehensive score order of the main components of each shrub species was: P. fruticosa>A. ordosica>L. bicolor>H. rhamnoides>O. davidiana>V. negundo var.heterophylla. Except P. fruticosa, the scores of factors of other shrub species under T4 treatment were negative, suggesting strong drought resistance. The native shrub species P. fruticosa and A. ordosica should be planted in the arid area of northern Hebei Province, while the native shrub species L. bicolorand the introduced shrub species H. rhamnoides can be selected as the vegetation community restoration species in the area with better water condition.

Key words: growth form, photosynthesis, drought stress, chlorophyll, leaf water potential.