Carbon assimilation in oak (Quercus spp.) populations under acute and chronic high-temperature stress

Abstract

This study tried to evaluate the influence of high temperatures (HT) on carbon assimilation of two oak species (Quercus cerris and Quercus robur). The screening of their populations, which are assumed to have a different resistance and acclimatization potential to adverse environmental conditions, can provide essential information for its implementation in reforestation strategies. By employing principal component analysis, the aim was to determine the most variable physiological characteristics of plants exposed to extremely HT during vegetation periods. After 2 d of HT treatment, a significant decline of photosynthetic and transpiration rates, and stomatal conductance were observed in plants of all investigated populations. The decrease of photosynthetic parameters after 2 d of HT treatment was regulated by the stomatal closure which caused the limitation of CO2 assimilation. Contrary, a chronic HT stress led to an increase in gs and inhibition of photosynthesis at the level of carboxylation.

Species-Level Differences in Osmoprotectants and Antioxidants Contribute to Stress Tolerance of Quercus robur L., and Q. cerris L. Seedlings under Water Deficit and High Temperatures

“…The ABA decrease observed in Q. cerris in response to high temperatures might result from substrate competition for common precursors between the biosynthesis of this phytohormone and photosynthetic pigments as previously found under stress conditions [50,104]. After exposure to high temperatures, significant changes in the antioxidant carotenoids were found on the same plants of the present study [52], reflecting a typical response to oxidative stress in several species [85,89] including Quercus [42,59,81,105]. Additional explanations of the lack of ABA induction under the applied temperature stress conditions can also rely on the increased stomatal conductance of the same seedlings as a possible consequence of the unlimited water supply [52].…”

“…Tolerance to the imposed stress conditions was evident in previous measurements of the physiological status on the same plants used for the present experiment [46,52,53]. Although under soil water deficit, a reduced leaf CO 2 assimilation and stomatal conductance was detected, the photosynthetic rates were still rather high (ca.…”

“…9-16 µmol m −2 s −1 in Q. robur) [46,53,62,63]. Similarly, thermotolerance of the investigated species was revealed by the maintenance of significant photosynthetic functionality, together with the lack of irreversible damage to the photosynthetic apparatus (i.e., photoinhibition of the PSII) even at the highest temperature (47 • C; [52,64]).…”

“…Therefore, the general aim of this work was to characterize the leaf-level capacity of antioxidant production and/or osmotic adjustments of Q. cerris and Q. robur in response to soil water deficit and increasing air temperatures through the measurements of a suite of different physiochemical parameters, including a newly-explored protective compound with a multifunctional role (i.e., DMSP). The examined seedlings from both species are expected to employ protective mechanisms to counteract oxidative stress under the applied stress conditions as the photosynthetic gas exchanges were reduced in response to the applied drought and heat stress on the same plants used for the present experiment [46,52,53]. The more specific objectives were to compare the constitutive and stress-induced changes in antioxidants, osmoprotectants, and phytohormones of the two oak species and to identify common and specific responses to drought and high temperatures.…”

Survival rate, adaptation ability and carbon production and sequestration of 21 green oak (Quercusrotundifolia Lam.) provenances at Mounts of Saida (western Algeria)

“…Growing the biomass of green oak by selecting the most suitable provenance for reforestation will contribute to an increase of organic substrate in the soil, as well as to the sequestration of more carbon (Oubrahim et al, 2015;Horak et al, 2019). Of the provenances from semi-arid forest ecosystems, those in the northern Zaccar (Tellian Atlas) showed the best results in the production of epigeous biomass at the rst site and those in the Jebel Aisssa (Saharan Atlas) showed the best results in the production of epigeous biomass at the second site.…”