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Article Dans Une Revue Tree Physiology Année : 2011

Water loss regulation in mature Hevea brasiliensis: effects of intermittent drought in the rainy season and hydraulic regulation

Résumé

Effects of soil and atmospheric drought on whole-tree transpiration (E-T), leaf water potential (psi(L)) and whole-tree hydraulic conductance (K-T) were investigated in mature rubber trees (Hevea brasiliensis, clone RRIM 600) during the full canopy stage in the rainy season in a drought-prone area of northeast Thailand. Under well-watered soil conditions, transpiration was tightly regulated in response to high evaporative demand, i.e., above reference evapotranspiration (ETo) similar to 2.2 mm day(-1) or maximum vapor pressure deficit similar to 1.8 kPa. When the trees experienced intermittent soil drought E-T decreased sharply when relative extractable water in the top soil was < 0.4. The midday leaf water potential (psi(md)) on sunny days did not change as a function of soil drought and remained stable at approximately -1.95 MPa, i.e., displaying isohydric behavior. The decrease in E-T was mainly due to the change in K-T. K-T remained constant over a wide range of environmental conditions and decreased sharply at low soil water availability. A simple hydraulic model incorporating critical minimum water potential and the response of whole-tree hydraulic conductance to relative extractable water correctly simulated patterns of transpiration over 6 months. We conclude that an explicit and simplified framework of hydraulic limitation hypothesis was sufficient to describe water use regulation of a mature rubber tree stand in water-limited conditions. Given the complexity of constraints in the soil-plant-atmosphere pathway, our results confirm the relevance of this approach to synthesize the overall behavior of trees under drought.

Dates et versions

hal-00964493 , version 1 (24-03-2014)

Identifiants

Citer

Supat Isarangkool Na S. I. N. Ayutthaya, Frederic C. F. C. Do, Krirk K. Pannangpetch, Junya J. Junjittakarn, Jean-Luc J.-L. Maeght, et al.. Water loss regulation in mature Hevea brasiliensis: effects of intermittent drought in the rainy season and hydraulic regulation. Tree Physiology, 2011, 31 (7), pp.751 - 762. ⟨10.1093/treephys/tpr058⟩. ⟨hal-00964493⟩
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