Substantial differences occur between canopy and ambient climate: Quantification of interactions in a...

Area of Science:

• Plant physiology
• Environmental science
• Agricultural engineering

Background:

• Organ temperature critically influences plant function and climate change response.
• A feedback loop exists between organ/leaf temperature and canopy climate, interacting with ambient climate.
• Understanding these dynamics in greenhouses is vital due to their use in crop experiments.

Purpose of the Study:

• Quantify differences between ambient and canopy climate within greenhouses.
• Measure leaf temperature variations relative to canopy air temperature.
• Identify key factors driving these microclimatic differences.

Main Methods:

• Experimental design to measure ambient and canopy climate parameters.
• Path analysis to model interactions within the greenhouse canopy-climate system.
• Quantification of differences in temperature and relative humidity (RH).

Main Results:

• Canopy climate can be up to 5°C cooler than ambient climate under high radiation, and 2°C cooler on cloudy days.
• Canopy relative humidity (RH) was up to 25% higher than ambient RH.
• Radiation significantly impacts climate differences, with supplementary light having counteracting indirect effects.

Conclusions:

• Leaf temperature deviates significantly from canopy air temperature, influenced by leaf area index (LAI), heating pipe temperature, and supplementary lighting.
• LAI and heating pipe temperature are key determinants of leaf-to-ambient air temperature differences.
• Strategies to decrease LAI or increase heating pipe temperature can reduce leaf-to-ambient temperature discrepancies.