Biomass Production and Predicted Ethanol Yield Are Linked with Optimum Photosynthesis in Phragmites karka under Salinity and Drought Conditions

Abstract

Plant photosynthesis and biomass production are closely associated traits but critical to unfavorable environmental constraints such as salinity and drought. The relationships among stress tolerance, photosynthetic mechanisms, biomass and ethanol yield were assessed in Phragmites karka. The growth parameters, leaf gas exchange and chlorophyll fluorescence of P. karka were studied when irrigated with the control and 100 and 300 mM NaCl in a nutrient solution and water deficit conditions (drought, at 50% water holding capacity). The plant shoot fresh biomass was increased in the low NaCl concentration; however, it significantly declined in high salinity and drought. Interestingly the addition of low salinity increased the shoot biomass and ethanol yield. The number of tillers was increased at 100 mM NaCl in comparison to the control treatment. High salinity increased the photosynthetic performance, but there were no significant changes in drought-treated plants. The saturated irradiance (Is) for photosynthesis increased significantly in low salinity, but it declined (about 50%) in high salt-stressed and (about 20%) in drought-treated plants compared to the control. The rates of dark respiration (Rd) and compensation irradiance (Ic) were decreased significantly under all treatments of salinity and drought, with the exception of unchanged Rd values in the control and drought treatments. A-Ci curve analyses revealed a significant improvement in the Jmax, Vc, max, and triose-phosphate utilization (TPU) at lower salinity levels but decreased at 300 mM NaCl and drought treatments compared to the control. In the chlorophyll fluorescence parameters (Fv/Fm, maximum photochemical quantum yield of PSII, and Y(NO)), the non-photochemical yields were not affected under the salt and drought treatments, although an effective photochemical quantum yield (YII) and electron transport rate (ETR) were significantly enhanced in water deficit compared to control plants. P. karka regulates an efficient photosynthesis mechanism to grow in saline and arid areas and can therefore be used as a sustainable biofuel crop.

Algal-Mediated Nanoparticles, Phycochar, and Biofertilizers for Mitigating Abiotic Stresses in Plants: A Review

“…Salinity stress can inhibit metabolic processes and result in early aging and cell death. Plants respond to salt stress through the closure of stomata, inhibition of cell expansion, and reduction of root surface area to reduce ion uptake [7].…”

Ipomoea cairica (L.) from Mangrove Wetlands Acquired Salt Tolerance through Phenotypic Plasticity

“…The Fv/Fm indicates the level of photoinhibition [88]. In this study, the Fv/Fm remained stable across both ecotypes under the two treatments, which indicated that there was little photoinhibition; this suggests that both ecotypes can adapt photosynthetically to salt stress [89,90]. A more substantial increase in NPQ in the terrestrial ecotype was observed under the salt treatment, which protected the photosynthetic apparatus from damage by dissipating excess light energy in the form of heat through non-photochemical processes [90].…”

Comparison between different lines reveals that Ipomoea cairica (L.) in mangrove wetlands acquires the ability to resist salt through phenotypic plasticity

“…The sharper reduction in the Y(II), qL, and ETR of the non-halophyte line under NaCl treatment indicates that its PSII reaction center is more susceptible to damage and inactivated to a greater extent than that of the halophyte. We also observed a greater increase in NPQ in the non-halophyte under salt treatment, which protected the photosynthetic apparatus from damage by dissipating excess light energy in the form of heat through nonphotochemical processes(Wei et al 2006; Moinuddin et al2017;Abideen et al 2022). Salt stress may disrupt the biochemistry of photosynthesis, which decreases the e ciency of PSI and PSII owing to disturbances in the integrity of chloroplasts(Ibrahim et al 2015;Stadnik et al 2022…”