Abstract:

Periploca sepium, Syringa oblata and Forsythia suspense are three native and widespread shrubs in the Loess hilly regions. In this paper, growth, water consumption and other physiological characteristics of these seedlings under artificially simulated drought stresses were investigated. The two-year old seedlings were grown under well-watered and two different water stressed conditions. Results showed that the water consumption and growth rate of F. suspense were significantly higher than that of P. sepium and S. oblata. While F. suspense had high water consumption and growth rate, S. oblata showed low water consumption. The peak water-consumption and the fastest growth period for three shrubs under three different soil water conditions all occurred mainly from June through August, which are the rainy season in the Loess hilly regions. The root to shoot ratios in plants of P. sepium and F. suspense increased significantly under water deficit conditions. However for S. oblate plants, the ratio of root to shoot was largest under 75% maximum field capacity (FC), followed by that under 40%FC soil water condition, and it was smallest under moderate drought stress (55%FC). S. oblate seedlings showed significantly higher level of water use efficiency (WUE) than P. sepium and F. suspense. In the present study, eleven indexes, which were significantly different between treatments, were used to conduct a principal components analysis (PCA), and the result showed that among these three shrubs, P. sepium had the highest drought resistance capacity, followed by S. oblate, and then F. suspense. These three shrubs also had different drought-resistant mechanisms.

Key words: native shrubs, drought adaptability, water use, water consumption characteristics, comprehensive evaluation