The response of leaf water potential and crassulacean acid metabolism to prolonged drought in Sedum rubrotinctum

• Published in: Plant physiology (Bethesda) Vol. 81; no. 2; pp. 678 - 680
• Main Authors: Teeri, J.A, Turner, M, Gurevitch, J
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.06.1986
• Subjects: Acidity; BIOCHEMICAL PATHWAYS; Biological and medical sciences; Carbon dioxide; CRASSULACEAE; Crassulacean acid metabolism; Drought; ESTACIONES DEL ANO; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; Leaves; METABOLISM; METABOLISME; METABOLISMO; Moisture content; PHOTOSYNTHESE; PHOTOSYNTHESIS; Photosynthesis, respiration. Anabolism, catabolism; Plant physiology and development; PLANT WATER RELATIONS; Plants; RELACIONES PLANTA AGUA; RELATION PLANTE EAU; SAISON; SEASONS; Short Communications; Solutes; Stems; STRESS; TITRATABLE ACIDITY; TURGENCIA; TURGESCENCE; TURGOR; Turgor pressure; VIA BIOQUIMICA DEL METABOLISMO; VOIE BIOCHIMIQUE DU METABOLISME; CAM-Type; Turgor; Drought resistance; Dicotyledones; Crassulaceae; Water deficit; Angiospermae; Spermatophyta; Photosynthesis; Water potential
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.81.2.678

Plants of Sedum rubrotinctum R. T. Clausen were studied in a greenhouse over a 2-year period without watering. Only the apical leaves survived and were turgid at the end of the experiment. The midday leaf water potential of these apical leaves was -1.20 megapascals, while the leaf water potential of comparable leaves on well-watered control plants was -0.20 megapascals. The unwatered plants appear to have maintained turgor by means of an osmotic adjustment. After 2 years without water the plants no longer exhibited a nocturnal accumulation of titratable acidity. However, the daytime levels of titratable acidity of the unwatered plants were more than 2-fold greater than the levels in well-watered control plants. Well-watered plants of S. rubrotinctum exhibited seasonal shifts in biomass stble carbon isotope ratios, indicating a greater proportion of day versus night CO2 uptake in the winter than in the summer. The imposition of water stress prevented the expression of this seasonal rhythm and restricted the plants to dark CO2 uptake.