RANGES OF PRIMARY ENVIRONMENTAL EFFECTS ON PLANTS

ISHS Acta Horticulturae 32: Symposium on Greenhouse Climate: Evaluation of Research Methods

RANGES OF PRIMARY ENVIRONMENTAL EFFECTS ON PLANTS

Author:

P. Gaastra

Abstract:
The papers deals with effects of various environmental factors and stomatal resistance on photosynthesis, transpiration and plant temperature. Most attention will be paid to transpiration and leaf temperature. The results are derived from measurements and from an analysis of the energy budget of a leaf.

Some of the underlying principles of the results were presented earlier*.

For various sets of conditions, met in glasshouse culture and in climate rooms, the relative importance of factors as:

absorbed short wave radiation and heat radiation,
vapour pressure deficit of the air,
boundary layer resistance in the air around the leaf,
stomatal resistance of the leaf,

is discussed for:

the range of transpiration, leaf temperature and photosynthesis obtainable,
the effect of changes in each of the conditions mentioned on the changes in transpiration, leaf temperature, and photosynthesis,
the value of the transpiration coefficient.

From the results can be derived, e. g. for a given flux of radiation absorbed, which parameters are most important for the control of transpiration, leaf temperature and photosynthesis.

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