Growth and leaf gas exchange in Populus euphratica across soil water and salinity gradients

Abstract

Soil water and salinity conditions of the riparian zones along the Tarim River, northwest China, have been undergoing alterations due to water use by human or climate change, which is expected to influence the riparian forest dominated by an old poplar, Populus euphratica. To evaluate the effects of such habitat alterations, we examined photosynthetic and growth performances of P. euphratica seedlings across experimental soil water and salinity gradients. Results indicated that seedlings were limited in their physiological performance, as evidenced by decreases in their height and biomass, and the maximal quantum yield of photosystem II (PSII) photochemistry (F v /F m ), the effective quantum-use efficiency of PSII (F v '/F m '), and photochemical quenching (q P ) under mild (18% soil water content, SWC; 18.3 g kg -1 soil salt content, SSC) and moderate (13% SWC, 22.5 g kg -1 SSC) water or salinity stress. However, seedlings had higher root/shoot ratio (R/S), increased nonphotochemical quenching (NPQ), and water-use efficiency (WUE) relative to control under such conditions. Under severe (8% SWC, 27.9 g kg -1 SSC) water or salinity stress, P. euphratica seedlings had only a fifth of biomass of those under control conditions. It was also associated with damaged PSII and decreases in WUE, the maximal net photosynthetic rate (P Nmax ), light-saturation point (LSP), and apparent quantum yield (α). Our results suggested that the soil conditions, where P.euphratica seedlings could grow normally, were higher than ~13% for SWC, and lower than ~22.5 g kg -1 for SSC, the values, within the seedlings could acclimate to water or salinity stress by adjusting their R/S ratio, improving WUE to limit water loss, and rising NPQ to dissipate excessive excitation energy. Once SWC was lower than 8% or SCC higher than ~28 g kg -1 , the seedlings suffered from the severe stress.

Photosynthetic and physiological responses of small seeded faba bean genotypes (Vicia faba L.) to salinity stress: identification of a contrasting pair towards salinity

“…The same results were obtained by Ben Chikha et al (2016) suggesting that biomass and photosynthetic parameters, especially total fresh mass and net CO2 assimilation, can be applied as suitable descriptors to assess salt tolerance in barley. Our results were also in agreement with those of Agastan et al (2000), Huang et al (2015), and Li et al (2013), who proved that photosynthetic capacity is an important trait for Table 4. Indices of tolerance to salt stress calculated from the most selective parameters in faba bean genotypes treated with 75 and 150 mM of NaCl.…”

Fluoranthene, a polycyclic aromatic hydrocarbon, inhibits light as well as dark reactions of photosynthesis in wheat (Triticum aestivum)

“…Five measurements were made per plot. Measurements were made between 11:00 AM and 12:00 PM (Li et al, 2013;Kataria and Guruprasad, 2014) under natural sunlight, ambient temperature and CO 2 concentration. On clear days at noon photosynthetic photon flux density (PPFD) was 1300-1600 mmol m À 2 s À 1 , air flow (500 mmol s À 1 ), and CO 2 concentration (350-380 ppm).…”

Ecophysiological Responses of Three Tree Species to a High-Altitude Environment in the Southeastern Tibetan Plateau

“…P. cathayana can grow fast in high altitude conditions with higher P n and biomass. The largest LSP of S. longistamina indicates that it has higher light-use efficiency in the study area, and largest biomass and WUE of S. longistamina suggests a better adaptation to the high irradiance [53]. LCP reflects the ability of plants to make use of low irradiance [28].…”