Control of stomatal conductance

 

 

Control of stomatal conductance by leaf water potential in Hymenoclea salsola (T. & G.), a desert subshrub.

by Comstock J., Mencuccini M. (1998)

in Plant, Cell & Environment 21: 1029–1038. –

Wiley Online Library |PubMed |

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3040.1998.00353.x/full

Schematic of the whole-plant photosynthesis cuvette with root pressure chamber. The cuvette was constructed of acrylic plastic lined with Teflon film. Internal mixing fans generated air movement 10–100 times the rate of air flow through the cuvette for gas exchange measurements. Temperature control was achieved by both water channels in the acrylic chamber walls and small radiators in the internal air flow pathway. The root pressure chamber was made of carbon steel and rated for pressures up to 4·0 MPa. The pressure chamber lid and the compression plate were formed by two steel half-circles which could be fitted around the intact plant stem to compress a neoprene gasket. – http://api.onlinelibrary.wiley.com/asset/v1/doi/10.1046%2Fj.1365-3040.1998.00353.x/asset/image_n%2FPCE_353_f1.gif?l=q8hDySOaNttEIdDP9D42UhSPCn%2BHKzXqYVuA9SabmExnDhSJcb7YXXRak4%2FJruKxT60H5vf%2BOJL1eC1RUWKaBg%3D%3D&s=%22d695782fa0f9473cbd5dea6c705f7155%22&a=wol

Abstract

The role of leaf water potential in controlling stomatal conductance (g_s) was examined in the desert subshrub Hymenoclea salsola. For plants operating at high irradiance, stomatal closure in response to high leaf-air humidity gradient (D) was largely reversed by soil pressurization.

Stomatal re-opening eliminated, on average, 89% of the closure normally induced by high D. Transpiration rates (E) reached under these conditions were far higher than maximal rates normally observed at any point of the D response. In situ stem psychrometry indicated that water flux at all times conformed to a simple Ohm’s-law analogy.

Under conditions of high D, E increased substantially in response to soil pressurization.

Stomatal regulation did not constrain E during this treatment, but did result in nearly constant minimum leaf water potentials.

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