Abstract: The diurnal course of photosynthetic rate, transpiration rate, and leaf water potential (Ψ_L) of five plant species in North Shaanxi loess hilly-gully region were measured in dry seasons. Based on the daily maximum photosynthetic and transpiration rates, daily total assimilation and transpiration, and diurnal change characteristics of Ψ_L, the test plants were classified into different eco-adaptation types.Panicum virgatum L. had high photosynthetic rate, low transpiration rate and high water use efficiency (WUE), and its drought adaption strategy was to delay dehydration by developing high Ψ_L. Medicago sativa had high photosynthetic and transpiration rates but low WUE, while Lespedeza dahurica had low photosynthetic and transpiration rates and low WUE. Their drought adaptation strategies were the same, namely, by increasing Ψ_L to delay dehydration.Bothriochloa ischaemum had high photosynthetic rate, relative high transpiration rate and medium WUE, and its drought-resistant strategy was to decrease Ψ_L to endure dehydration.Astragalus adsurgens had similar characteristics in diurnal courses of photosynthesis with B. ischaemum, and its drought adaption strategy was to delay dehydration by developing low Ψ_L.

Key words: Genotype of Frankia, Gaoligong Mountains, IGS PCR-RFLP