关键词: CO₂浓度升高, 土壤水分, 氮肥用量, 蒸散, 水分利用效率

Abstract: By using a water supply device with epikarst water-limestone-soil columniation to simulate karst environment, and adopting press-volume (P-V) technique, a water-controlled experiment was conducted to study the changes of Cyclobalanopsis glaucawater parameters including daily water potential (P), water potential at saturated point (ψ^sat_s), water potential at turgor loss point (ψ^tlp_s), relative osmotic water content at turgor loss point (ROWC^tlp), relative water content at turgor loss point (RWC^tlp), relative content of apoplastic water (AWC), and the difference between ψ^sat_s and ψ^tlp_s(ΔP) under drought stress. In treatment no-epikarst water-limestone-soil, the ROWC^tlp, RWC^tlp, ψ^sat_s, and ψ^tlp_s decreased and the AWC increased with intensifying soil drought; while in treatment epikarst water-limestone-soil, these water parameters had no significant changes along with soil water variation. Under no-epikarst water condition, the water parameters of C. glauca were predominantly affected by soil water content, and the drought tolerance of C. glauca was enhanced with increasing soil drought in a certain range of drought stress.

Key words: CO₂ concentration enrichment, Soil moisture, Nitrogen fertilizer rates, Evapotranspiration, WUE