TRANSPIRATION OF ROSES IN GREENHOUSES

Rose plants absorb most of the solar radiation entering the greenhouse.
In a well-irrigated vigorously growing crop, high transpiration rates during morning and midday hours dissipate a large proportion of the absorbed radiation as latent heat.
The remaining radiation heats the crop and the air.
During the afternoon, with a similar load of absorbed radiation and higher outside air temperature and wind velocity, the crop transpires less than during the morning, yet it still cools incoming air.
Analysis of decoupling coefficients shows that greenhouse plants are more decoupled from ambient climate during morning and noon periods than during afternoons.
In decoupled systems, transpiration depends mainly on radiation; canopy resistance and ambient humidity have only a secondary effect.
During afternoons, higher wind velocity and lower transpiration rates increase the coupling of the crop to ambient air, resulting in the observed cooling.

World Congress on Soilless Culture: Agriculture in the Coming Millennium

E. Dayan, M. Fuchs, Z. Plaut, E. Presnov, A. Grava, E. Matan, A. Solphoy, U. Mugira, N. Pines

Greenhouse, transpiration, roses, natural ventilation, climate control.

https://doi.org/10.17660/ActaHortic.2001.554.25