Substantial differences occur between canopy and ambient climate: Quantification of interactions in a greenhouse-canopy system

Abstract

Organ temperature and variation therein plays a key role in plant functioning and its responses to e.g. climate change. There is a strong feedback between organ, especially leaf, temperature and the climate within the canopy (canopy climate), which in turn interacts with the climate outside the canopy (ambient climate). For greenhouses, the determinants of this interplay and how they drive differences between canopy and ambient climate are poorly understood. Yet, as many experiments on both regular greenhouse crops and field crops are done in greenhouses, this is crucial to know. Therefore, we designed an experiment to quantify the differences between ambient and canopy climate and leaf temperature. A path analysis was performed to quantify the interactions between components of the greenhouse canopy-climate system. We found that with high radiation the canopy climate can be up to 5˚C cooler than the ambient climate, while for cloudy days this was only 2˚C. Canopy relative humidity (RH) was up to 25% higher compared to ambient RH. We showed that radiation is very important for these climate differences, but that this effect could be partly counteracted by turning off supplementary light (i.e. due to its indirect effects e.g. changing light distribution). Leaf temperature was substantially different, both higher and lower, from the canopy air temperature. This difference was determined by leaf area index (LAI), temperature of the heating pipe and the use of supplementary light, which all strongly influence radiation, either shortwave or thermal radiation. The difference between leaf and ambient air temperature could be decreased by decreasing the LAI or increasing the temperature of the heating pipe.

Tomato leaves under stress: A comparison of stress response to mild abiotic stress between a cultivated and a wild tomato species

“…This may result also in an increase in the canopy and leaf temperature due to radiation and warmth produced by the lamps. In previous studies, additional radiation in our range increased the canopy temperature by 0.38 - 1 K (Nelson and Bugbee, 2015; Van Westreenen et al, 2020). In this respect, chilling stress might have been less pronounced in the combination of elevated light intensities and chilling temperatures during day conditions.…”

Variation of Photosynthetic Induction in Major Horticultural Crops Is Mostly Driven by Differences in Stomatal Traits

“…The patterns of irradiance fluctuations appear to be very important in determining the discrepancy between simulating daily carbon gain with and without the effects of photosynthetic induction ( Murakami and Jishi, 2021 ). However, only few studies quantified irradiance fluctuations in greenhouses at the relevant time scales ( van Westreenen et al, 2020 ), hampering such estimations for the greenhouse production context. Moreover, previous irradiances potentially affect photosynthetic induction responses to the upcoming irradiance ( Jackson et al, 1991 ; Kaiser et al, 2017 ).…”

Plant heat stress: Concepts directing future research

“…In most cases, the temperatures recorded and presented, and the results interpreted, are based on the imposed air temperature in controlled chamber, glasshouse and field environments or the naturally occurring hot air temperature in other field‐based studies (Bahuguna et al, 2015; Dusenge et al, 2020; Reich et al, 2018; Sarwar et al, 2019). However, there are often large differences between the ambient air temperature and the tissue temperature that the plant actually experiences (Schymanski, Or, & Zwieniecki, 2013; Shi, Ishimaru, et al, 2015; Singsaas et al, 1999; Westreenen et al, 2020). Under sunny conditions, the canopy air temperature (60 cm below the top of the canopy) in a greenhouse with rose cuttings was 5°C lower than the ambient air temperature at noon, while on a cloudy day, it was at most 2°C lower (Westreenen et al, 2020), while leaves at the top of an oak tree were up to 15°C warmer than air temperature (Singsaas et al, 1999).…”

“…However, there are often large differences between the ambient air temperature and the tissue temperature that the plant actually experiences (Schymanski, Or, & Zwieniecki, 2013; Shi, Ishimaru, et al, 2015; Singsaas et al, 1999; Westreenen et al, 2020). Under sunny conditions, the canopy air temperature (60 cm below the top of the canopy) in a greenhouse with rose cuttings was 5°C lower than the ambient air temperature at noon, while on a cloudy day, it was at most 2°C lower (Westreenen et al, 2020), while leaves at the top of an oak tree were up to 15°C warmer than air temperature (Singsaas et al, 1999). Similarly, rice spikelet tissue temperature measured using thermocouples revealed a 0.4, 1.3 and 1.8°C lower temperature compared to ambient air temperatures of 30, 35 and 38°C, respectively (Jagadish, Craufurd, & Wheeler, 2007).…”