Concurrent Increases in Leaf Temperature With Light Accelerate Photosynthetic Induction in Tropical Tree Seedlings

Abstract

Leaf temperature changes with incident light intensity, but it is unclear how the concurrent changes influence leaf photosynthesis. We examined the time courses of CO 2 gas exchanges and chlorophyll fluorescence of seedling leaves in four tropical tree species in response to lightflecks under three different temperature conditions. The three conditions were two constant temperatures at 30°C (T 30) and 40°C (T 40), and a simulated gradually changing temperature from 30 to 40°C (T dyn). The time required to reach 50% of the full photosynthetic induction under T 40 was similar to, or even larger than, that under T 30. However, the induction of assimilation rate (A) and electron transport rate of photosystem II (ETR II) and Rubisco activation process were generally accelerated under T dyn compared to those at either T 30 or T 40. The acceleration in photosynthetic induction under T dyn was significantly greater in the shade-tolerant species than in the shade-intolerant species. A modified photosynthetic limitation analysis indicated that the acceleration was likely to be mainly due to ETR II at the early stage of photosynthetic induction. The study suggests that concurrent increases in leaf temperature with light may increase leaf carbon gain under highly fluctuating light in tropical tree seedlings, particularly in shade-tolerant species.

Effects of Environmental and Non-Environmental Factors on Dynamic Photosynthetic Carbon Assimilation in Leaves under Changing Light

“…High temperature also decelerated photosynthetic induction in Oryza sativa [ 40 ]. Research by Kang et al showed that the effect of high temperature on photosynthetic induction was species-dependent: raising the temperature from 30 °C to 40 °C decelerated photosynthetic induction in Croton argyratus, Shorea leprosula and Lepisanthes senegalensis , but accelerated photosynthetic induction in Neobalanocarpus heimii [ 41 ].…”

Responses of photosystem to long-term light stress in a typically shade-tolerant species Panax notoginseng

“…Moreover, activation of CEF-PSI can also prevent PSI from photoinhibition and photooxidative damage through alleviating the over-reduction of PSI acceptor side and reducing the synthesis of superoxide anions in PSI ( Sagun et al., 2019 ; Yang et al., 2019a ; Yang et al., 2019b ). Photooxidative damage is avoided in the shade-tolerant species such as Vanilla orchid , Neobalanocarpus heimii and Lepisanthes senegalensis through enhancing CEF around PSI when it is exposed to high light ( Kang et al., 2020 ; Ko et al., 2020 ). Nevertheless, it is still unknown about a relationship between the photoprotective strategies and the sensitivity of the shade-tolerant species to high light.…”

Growth Light Quality Influences Leaf Surface Temperature by Regulating the Rate of Non-Photochemical Quenching Thermal Dissipation and Stomatal Conductance

“…Furthermore, our current understanding of light-driven modification of leaf temperature is restricted to analyses concerning changes in incident light intensity [10]. In such cases, when plants are grown under unified light, the actual foliar temperature measured under changing light intensity is primarily related to stomatal aperture regulation rather than NPQ amplitude [11].…”

“…Thus, the underlying concept of the present study is to elucidate the influence of spectrum-related thermal dissipation and stomatal conductance regulation on actual foliar temperature, leading to differences in evaporation and, consequently, water use efficiency in plants grown under different light regimes. Furthermore, as associated fluctuations in T leaf under different light regimes are expected to influence photosynthesis directly, because it is a highly temperature-dependent process [10], we also analysed the photosynthetic activity of plants.…”