Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation

Abstract

Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m−2 s−1. Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two “sun-leaf-like” surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature.

De novo assembly and analysis of the transcriptome of Rumex patientia L. during cold stress

“…patientia L. is a new type of high-protein forage feed and is also a good ground cover plant for effectively preventing soil erosion and improving the ecological environment [24,25]. The tolerance of R .…”

Two sides to every leaf: water and CO2 transport in hypostomatous and amphistomatous leaves

“…The wider occurrence of independent control on adaxial vs abaxial stomatal conductance, as well as the potential benefit in terms of water‐use efficiency, remain to be determined. A critical element of research into this control is the effect of leaf flutter due to wind (Zhang et al ., ), which may equalise light intensity and temperature across the leaf surfaces at short time scales.…”

Effects of cadmium-induced stress on essential oil production, morphology and physiology of lemon balm (Melissa officinalis L., Lamiaceae)

“…This effect was most noticeable in the stomata lengths on upper surfaces of the leaves (52% decrease) at the highest Cd concentration (stomata lengths decreased by 16% on lower surfaces) (P≤0.05). Photosynthetic gas exchange is more sensitive to stress factors on upper surfaces than lower surfaces (Zhang et al, 2016). In our study, it was clear that the plant growth and development mechanism was adversely affected due to the decrease of photosynthetic gas exchange caused because Cd stress affected stomatal structures (stomata amount and sizes) more on the upper surfaces of the leaves than on the lower surfaces.…”