Low Salinity Improves Photosynthetic Performance in Panicum antidotale Under Drought Stress

Abstract

Salinity and drought are two often simultaneously occurring abiotic stresses that limit the production of food crops worldwide. This study aimed to distinguish between the separate and combined impacts of drought and salinity on the plant response. Panicum antidotale was cultivated in a greenhouse under the following growth conditions: control, 100 mM NaCl (100) and 300 mM NaCl (300) salinity, drought (D; 30% irrigation), and two combinations of salinity and drought (100 + D and 300 + D). The growth response was as follows: 0 ≈ 100 > 100 + D > > D ≈ 300 ≈ 300 + D. Growth correlated directly with photosynthesis. The net photosynthesis, stomatal conductance, intercellular CO 2 , transpiration, ribulose 1,5-bisphosphate carboxylase (Rubisco), ribulose 1,5-bisphosphate (RuBP) regeneration, and triose phosphate utilization protein (e.g., phosphoenolpyruvate carboxylase) were highest in the control and declined most at 300 + D, while 100 + D performed significantly better as compared to drought. Maximum and actual photosystem II (PSII) efficiencies, along with photochemical quenching during light harvesting, resemble the plant growth and contemporary CO 2 /H 2 O gas exchange parameters in the given treatments. Plant improves water use efficiency under salt and drought treatments, which reflects the high water conservation ability of Panicum. Our findings indicate that the combination of low salinity with drought was able to minimize the deleterious effects of drought alone on growth, chlorophyll content, cell integrity, photosynthesis, leaf water potential, and water deficit. This synergetic effect demonstrates the positive role of Na + and Cl − in carbon assimilation and osmotic adjustment. In contrast, the combination of high salinity and drought enforced the negative response of plants in comparison to single stress, demonstrating the antagonistic impact of water availability and ion toxicity.

Drought tolerance inBrassica napusis accompanied with enhanced antioxidative protection, photosynthetic and hormonal regulation at seedling stage

“…Generally, variations in Fv/Fm are often confirmed by the concentration changes of specific photosynthetic pigments and cell structure modulations that may be influenced by several environmental factors affecting PSII activity such as light, nutrient status, and temperature (Miao et al, 2020). Several studies showed that drought stress may affect the reaction center and obstruct the electron transportation system, which ultimately leads to a reduction in Fv/Fm (Hussain et al, 2020). In addition, our findings also indicate that drought stress has a more severe negative effect on the Fv/Fm of cultivar GY605 than ZD622 and ZS11 (Figure 2F), which suggests that GY605 was more sensitive to drought stress than ZD622 and ZS11.…”

“…In con- that may be influenced by several environmental factors affecting PSII activity such as light, nutrient status, and temperature (Miao et al, 2020). Several studies showed that drought stress may affect the reaction center and obstruct the electron transportation system, which ultimately leads to a reduction in Fv/Fm (Hussain et al, 2020).…”

Ethylene and Sulfur Coordinately Modulate the Antioxidant System and ABA Accumulation in Mustard Plants under Salt Stress

“…Salinity is one of the most deleterious among abiotic stresses, causing ion imbalance, nutrient deficiency, and oxidative stress [ 3 ]. The high content of Na + and Cl − disturbs efficient stomatal regulation together with the reduction in photosynthesis due to the over-production of reactive oxygen species (ROS) [ 4 , 5 , 6 ]. Stomatal closure has also been associated with membrane damage and disturbs the activity of various enzymes, especially those involved in ATP synthesis and photosynthesis [ 7 ].…”

Role of beneficial elements in plants: implications for the photosynthetic process

“…Martínez et al (2005) reported higher values in PN and increase in WUE levels in Na-treated plants (with respect to controls) of Atriplex halimus (C4 xerohalophyte species) under water stress (Table 3). Moreover, in Panicum antidotale, Hussain et al (2020) observed an alleviation of the negative impact of drought on gas-exchange parameters in Na plants (100 mM NaCl) by maintaining higher values in PN, gs, E, Vcmax, and Jmax with respect to drought Na-untreated plants. These beneficial effects are related to a positive impact of the low Na concentration on photochemical reactions and, in particular, stimulating photosynthetic pigments and photochemical PSII effi ciency.…”