Comparative study of water uptake and photosynthetic gas exchange between scrub and fringe red mangroves, Rhizophora mangle L.
Tóm tắt
The red mangrove (Rhizophora mangle L.) occurs frequently in both scrub and fringe mangrove forests. Our previous study demonstrated that individuals of this mangrove species growing in scrub and fringe forests differ significantly in both morphological and physiological characteristics. To further characterize physiological differences between scrub and fringe mangroves, we compared their differences in water uptake and photosynthetic gas exchange during different seasons. In the wet season (June–October, 1990), scrub mangroves showed lower δD and δ18O values of stem water than fringe mangroves, indicating more usage of rain-derived freshwater. In the dry season (Jan–April, 1991), however, scrub mangroves utilized the same water source as fringe mangroves, reflected by their similar δD and δ18O values of stem water. Consistently, there were significant differences in predawn water potentials between scrub and fringe mangroves in the wet season (October 1990) with higher values for scrub mangroves, but no significant differences in the dry season (January 1991). Higher elevation in the scrub forest seems to be the major factor responsible for the shift of water sources in scrub mangroves. On Apr. 27 and Aug. 8, 1990, scrub mangroves showed lower CO2 assimilation rate, stomatal conductance, and intercellular CO2 concentration than fringe mangroves. There were no differences in these gas exchange characteristics on the other two measuring dates: Oct. 17, 1990 and Jan. 11, 1991. Instantaneous water use efficiency was significantly higher for scrub mangroves than for fringe mangroves on three of the four sampling dates. Similarly, leaf carbon isotope discrimination of scrub mangroves was always significantly lower than that of fringe mangroves, indicating higher long-term water use efficiency. Higher water use efficiency in scrub mangroves is a result of stomatal limitation on photosynthesis, which may entail considerable carbon cost to the plants.
Tài liệu tham khảo
Ball MC (1988a) Ecophysiology of mangroves. Trees 2:129–142
Ball MC (1988b) Salinity tolerance in the mangroves, Aegiceras corniculatum and Avicennia marina. I. Water use in relation to growth, carbon partitioning and salt balance. Aust J Plant Physiol 15:447–464
Bigeleisen J, Perlman ML, Prosser HC (1952) Conversion of hydrogenic materials to hydrogen for isotopic analysis. Anal Chem 24:1356–1357
Cowan IR (1977) Stomatal behavior and environment. Adv Bot Res 4:117–228
Duke NC, Bunt JS, Williams WT (1984) Observations on the floral and vegetative phenologies of North-eastern Australian mangroves. Aust J Bot 32:87–99
Ehleringer JR (1990) Correlations between carbon isotope discrimination and leaf conductance to water vapor in common beans. Plant Physiol 93:1422–1425
Epstein S, Mayeda T (1953) Variation of O-18 content of water from natural sources. Geochim Cosmochim Acta 42:213–224
Geber MA, Dawson TE (1990) Genetic variation in and covariation between leaf gas exchange, morphology, and development in Polygonum arenastrum, and annual plant Oecologia 85:153–158
Farquhar GD, Ball MC, von Caemmerer S, Roksandic Z (1982) Effect of salinity and humidity on δ13C values of halophytes-evidence for diffusional isotope fractionation determined by the ratio of intercellular/atmospheric CO2 under different environmental conditions. Oecologia 52:121–137
Farquhar GD, Ehleringer JR, Hubick KT (1989) Carbon isotope discrimination and photosynthesis. Ann Rev Plant Physiol Mol Biol 40:503–537
Hubick KT, Farquhar GD, Shorter R (1986) Correlation between water-use efficiency and carbon isotope discrimination in diverse peanut (Arachis) germplasm. Aust J Plant Physiol 13:803–815
Lin G, Sternberg LSL (1991) Differences in morphology, carbon isotope ratios and photosynthesis between scrub and fringe mangroves. Aquat Bot (in press)
Lugo AE, Snedaker SC (1974) The ecology of mangroves. Ann Rev Ecol Syst 5:39–64
Moore RT, Miller PC, Ehleringer J, Lawrence W (1973) Seasonal trends in gas exchange characteristics of three mangrove species. Photosynthetica 7:387–394
Naidoo G (1989) Seasonal plant water relations in a South African mangrove swamp. Aquat Bot 33:87–100
Sternberg LdSL, Ish-Shalom-Gordon N, Ross M, O'Brien J (1991) Water relations of coastal plant communities near ocean/freshwater boundary. Oecologia 88:305–310
Sternberg LdSL, Swart PK (1987) Utilization of freshwater and ocean water by coastal plants of southern Florida. Ecology 68:1898–1905
Swart PK, Sternberg LdSL, Steinen R, Harrison S (1989) Controls on the oxygen and hydrogen isotopic composition of the waters of Florida Bay, U.S.A. Chemical Geology (Isotope Geoscience section) 79:113–123
Teas HJ (1979) Silviculture with saline water. In Hollaender A (ed) The biosaline concept. Plenum Publishing Corporation, New York. pp 117–161
Werner A, Stelzer R (1990) Physiological responses of the mangrove Rhizophora mangle grown in the absence and presence of NaCl. Plant Cell & Environ 13:243–255
White JWC, Cook ER, Lawerence JR, Broecker WS (1985) The D/H ratios of sap in trees: implications for water sources and tree ring D/H ratios. Geochim Cosmochim Acta 49:237–246