How the Plant Temperature Links to the Air Temperature in the Desert Plant Artemisia ordosica

Abstract

Plant temperature (Tp) is an important indicator of plant health. To determine the dynamics of plant temperature and self-cooling ability of the plant, we measured Tp in Artemisia ordosica in July, in the Mu Us Desert of Northwest China. Related factors were also monitored to investigate their effects on Tp, including environmental factors, such as air temperature (Ta), relative humidity, wind speed; and physiological factors, such as leaf water potential, sap flow, and water content. The results indicate that: 1) Tp generally changes in conjunction with Ta mainly, and varies with height and among the plant organs. Tp in the young branches is most constant, while it is the most sensitive in the leaves. 2) Correlations between Tp and environmental factors show that Tp is affected mainly by Ta. 3) The self-cooling ability of the plant was effective by midday, with Tp being lower than Ta. 4) Increasing sap flow and leaf water potential showed that transpiration formed part of the mechanism that supported self-cooling. Increased in water conductance and specific heat at midday may be additional factors that contribute to plant cooling ability. Therefore, our results confirmed plant self-cooling ability. The response to high temperatures is regulated by both transpiration speed and an increase in stem water conductance. This study provides quantitative data for plant management in terms of temperature control. Moreover, our findings will assist species selection with taking plant temperature as an index.

Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land‐surface modelling

“…The observed values suggest α somewhat larger than 1.26, but well within the theoretically predicted range (up to 1.391 according to Huntingford & Monteith, ). A similar diurnal time course of Δ T has been observed in other studies and environments, for example by Yu et al () in a desert.…”

FACTORS AFFECTING PHENOLOGY OF DIFFERENT Citrus VARIETIES UNDER THE TEMPERATE CLIMATE CONDITIONS OF SANTA FE, ARGENTINA

“…Based on previously published literature, we expected that the increase in leaf temperature of our Citrus plants would be directly proportional with solar radiation (MEDINA et al, 2002). Consequently, our calculation of plant heat accumulation based on air temperature underestimated the actual plant heat accumulation because air temperature was lower than leaf temperature (YU et al, 2015). This aspect was relevant because the median temperature in July was very close to the threshold temperature for Citrus metabolism (-1.3ºC) (Table 1).…”

“…Previously published research shows that under low temperature conditions, especially under low soil or substrate temperatures, Citrus plants' metabolism is severely reduced; low night temperatures cause stomatal closure (via a decrease in stomatal conductance) and reduce net daily photosynthesis (via a decrease in biochemical reaction rates of carboxylation and ribulose-1,5-bisphosphate [RuBP] regeneration) (RIBEIRO et al, 2009;SANTOS et al, 2011). In addition, stomatal conductance reduction also increases leaf temperature in relation to air temperature (RIBEIRO et al, 2009), because plant transpiration is reduced (YU et al, 2015).…”

Low predictability of energy balance traits and leaf temperature metrics in desert, montane and alpine plant communities

“…This divergence can be summarized in terms of two temperature metrics: first, a 'thermal offset': which describes the magnitude of the difference between leaf and air temperature; and second, a 'thermal coupling strength': which describes the slope of the relationship between T leaf and T air as both vary over time. Many empirical studies have shown that these temperature metrics vary widely in nature (Dong, Prentice, Harrison, Song, & Zhang, 2017;Gates, Hiesey, Milner, & Nobs, 1964;Linacre, 1967;Michaletz et al, 2016;Upchurch & Mahan, 1988;Yu et al, 2015). For example, thermal offsets may exceed ±15°C in deserts, tropical forests or the alpine, while thermal coupling strengths may vary from <1 (limited homeostasis) to >1 (megathermy) across biomes (Blonder & Michaletz, 2018;Michaletz et al, 2016).…”