Responses of photosynthesis and water relations to rainfall in the desert shrub creosote bush (Larrea tridentata) as influenced by municipal biosolids

• Published in: Journal of arid environments 2000-12, Vol.46 (4), p.397-412
• Main Authors: Yan, Shunguo, Wan, Changgui, Sosebee, Ronald E, Wester, David B, Fish, Ernest B, Zartman, Richard E
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; drought; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Larrea tridentata; Larrea tridentate; Mexico; photosynthesis; Plants and fungi; recovery; USA; water relations; Water relations, transpiration, stomata
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1006/jare.2000.0682

Responses of photosynthesis (Pn), stomatal conductance (gs), pre-dawn leaf water potential (Ψlp) and leaf water content (ωl) of creosote bush to 10 rainfall events in the Chihuahuan Desert were investigated. Infiltration of rainwater was manipulated by applying municipal biosolids. The responses of Pnand water relation parameters to rainfall (>10 mm) were mainly dependent upon drought severity: (1) following a moderate drought, Pn, gs, Ψlpand ωlrecovered to corresponding values of irrigated plants within 2 days after a 23-mm rainfall; (2) Ψlpand gsresponded to a 15-mm rainfall within 2 days, following a 25-day drought, whereas responses of Pnand ωlwere delayed for several days; (3) responses of Pn, gs, Ψlpand ωlto a 14·7-mm rainfall were all delayed for several weeks following a 110-day drought, but the delay was longer in Pn, gsand ωlthan in Ψlp. Creosote bush responded to small rainfall events (approximately 6 to 8 mm) with an increase in Ψlp, but without noticeable changes in gsand Pn, suggesting a strong stomatal control of water loss even though xylem embolism was reduced. Biosolids applied at high rates (3·4 and 9 kgm−2) decreased the soil water by 2 to 4 mm following rainfall events, and this in turn delayed and decreased the responses of Pnand water relation parameters to rainfall. Pnand gswere linearly related to ωland exponentially related to Ψlp. With the generally coincidental responses of Pnor gsand ωlto rainfall, we concluded that the responses of Pnand gsto rainfall were dependent on leaf rehydration which resulted from restored hydraulic conductance following drought.