Sustainable Biochar and/or Melatonin Improve Salinity Tolerance in Borage Plants by Modulating Osmotic Adjustment, Antioxidants, and Ion Homeostasis

Abstract

Salinity is persistently a decisive feature confining agricultural sustainability and food security in arid and semi-arid regions. Biochar (Bi) has been advocated as a means of lessening climate changes by sequestering carbon, concurrently supplying energy and rising crop productivity under normal or stressful conditions. Melatonin (Mt) has been shown to mediate numerous biochemical pathways and play important roles in mitigating multi-stress factors. However, their integrated roles in mitigating salt toxicity remain largely inexpressible. A completely randomized design was conducted to realize the remediation potential of Bi and/or Mt in attenuation salinity injury on borage plants by evaluating its effects on growth, water status, osmotic adjustment, antioxidant capacity, ions, and finally the yield. Salinity stress significantly decreased the plant growth and attributed yield when compared with non-salinized control plants. The depression effect of salinity on borage productivity was associated with the reduction in photosynthetic pigment and ascorbic acid (AsA) concentrations, potassium (K+) percentage, K+-translocation, and potassium/sodium ratio as well as catalase (CAT) activity. Additionally, borage plants’ water status was disrupted by salinity through decreasing water content (WC), relative water content (RWC), and water retention capacity (WTC), as well as water potential (Ψw), osmotic potential (Ψs), and turgor potential (Ψp). Moreover, salinity stress evoked oxidative bursts via hyper-accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as protein carbonyl, which is associated with membrane dysfunction. The oxidative burst was connected with the hyper-accumulation of sodium (Na+) and chloride (Cl−) in plant tissues, coupled with osmolytes’ accumulation and accelerating plants’ osmotic adjustment (OA) capacity. The addition of Bi and/or Mt had a positive effect in mitigating salinity on borage plants by reducing Cl−, Na+, and Na+-translocation, and oxidative biomarkers as well as Ψw, Ψs, and Ψp. Moreover, Bi and/or Mt addition to salt-affected plants increased plant growth and yield by improving plant water status and OA capacity associated with the activation of antioxidant capacity and osmolytes accumulation as well as increased photosynthetic pigments, K+, and K+/Na+ ratio. Considering these observations, Bi and/or Mt can be used as a promising approach for enhancing the productivity of salt-affected borage plants due to their roles in sustaining water relations, rising solutes synthesis, progressing OA, improving redox homeostasis, and antioxidant aptitude.

Morpho-Physiological and Anatomical Alterations of Salt-Affected Thompson Seedless Grapevine (Vitis vinifera L.) to Brassinolide Spraying

“…Plants undergo salinity critically once they are grown in saline conditions. The drastic impact of salinity as recorded in the current investigation on plant growth was provided with earlier findings for numerous plants [6][7][8]11,16,17]. The overall decline under salinity might be caused by the negative impact of salinity on different metabolic processes and molecular alterations, i.e., photosynthesis, nutrient homeostasis, stomatal resistance, and ROS production in different plants [6,8,16].…”

“…Salinity is considered one of the prime exigent environmental threats against sustainable food production [6][7][8]. About 33% of irrigated croplands are classified as salt-affected soil, which may exceed 50% by 2050 [9].…”

“…About 33% of irrigated croplands are classified as salt-affected soil, which may exceed 50% by 2050 [9]. The undesirable impacts of excess salinity on crop development are possibly attributed to osmotic stress, cytotoxicity provoked by excess sodium (Na + ) and chloride (Cl − ), nutritional imbalances, decreased turgor, and leaf anatomical modifications [6,8,10,11]. Likewise, excess Na + evoked the excess generation of toxic reactive oxygen species (ROS) that may interrupt cellular functions and negatively affect metabolic processes.…”

“…ROS generation usually impedes the redox homeostasis, resulting in loosening photosynthetic effectiveness [12], modifying nitrogen and osmolytes assimilation, and decreasing nutrient absorption, changing phytohormones profile and genes expression [13]. The studies by Farouk et al [6], Farouk and Al-Huqail [8], and Kaur et al [11] showed that excess salinity activates the antioxidant enzymes in plant tissues. In this regard, superoxide dismutase (SOD) accelerates the conversion of superoxide radicals (O −1 ) to hydrogen peroxide (H 2 O 2 ), while peroxidase (POD) and catalase (CAT) decompose H 2 O 2 into water (H 2 O) and O 2 [14,15].…”

“…In this regard, superoxide dismutase (SOD) accelerates the conversion of superoxide radicals (O −1 ) to hydrogen peroxide (H 2 O 2 ), while peroxidase (POD) and catalase (CAT) decompose H 2 O 2 into water (H 2 O) and O 2 [14,15]. Additionally, salinity induces necrosis of adult leaves, and increasing Na + influx and potassium (K + ) leakage leads to a superior Na + /K + ratio in plant tissues [6,8,16]. In this regard, salinity normally disturbs the growth and yield of grapevine as well as induces physiological processes [5].…”