Microwave irradiation and citric acid assisted seed germination and phytoextraction of nickel (Ni) by Brassica napus L.: morpho-physiological and biochemical alterations under Ni stress

Abstract

The complex bio-geochemistry of soil allows pollutant to persist for a longer period of time which further decreased the fertility and natural composition of land. Nickel, an inorganic pollutant, coming from a wide range of industrial and manufacturing units possesses serious threat to soil degradation and crop productivity around the world. The present study was carried to evaluate the combined role of microwave irradiation (MR) and citric acid (CA) on the phytoextraction potential of Brassica napus L. under Ni stress. An initial seed germination test was conducted to select effective time scale of MR exposure. Highest seed germination was observed at exposure of 2.45 GHz frequency for 30 s. Healthy seeds of B. napus L. genotype Faisal Canola (RBN-03060) treated with MR at 2.45 GHz for 30 s were sown in plastic pots filled with 5 kg of soil. Nickel and CA applied exogenously in solution form with different combinations to both MR-treated and untreated B. napus plants. The MR-treated plants showed higher growth, biomass, photosynthetic pigments (Chl a, b, total, and carotenoids) and activities of antioxidant enzymes (SOD, POD, APX, CAT) as compared to untreated plants who showed higher reactive oxygen species (MDA, HO) and electrolyte leakage. Increasing Ni concentration significantly decreased the physiological and biochemical attributes of B. napus both in MR-treated and untreated plants. The addition of CA alleviated Ni-induced toxic effects in both MR-treated and untreated plants by improving antioxidant defense system. The degree of Ni stress mitigation was higher in MR-treated plants. The Ni concentration was higher in root, stem, and leaves of MR-treated plants under CA application as compared to untreated plants. The present study concluded that seeds treated with MR before sowing showed higher accumulation and concentration of Ni from soil, and this phenomenon boosted with the application of CA.

Melatonin Modulates Plant Tolerance to Heavy Metal Stress: Morphological Responses to Molecular Mechanisms

“…Plants produce and accumulate osmolytes such as soluble sugars, trehalose, amino acids, and betaines to counteract stress-induced osmotic imbalance. In addition, these osmolytes participate in cellular energy transfer, stabilize membranes and proteins, scavenge ROS, chelate HMs, and minimize metal uptake to cope with metal-induced osmotic, ionic, and oxidative stresses [ 62 , 63 ]. Plants with better osmoprotectant biosynthesis are adaptable to stress [ 64 ].…”

Citric acid enhanced phytoextraction of nickel (Ni) and alleviate Mentha piperita (L.) from Ni-induced physiological and biochemical damages

“…The toxicity of Ni mainly depends on its concentration in media (Rathika et al 2020). Nickel is mostly present in plant roots at high concentrations and less is translocated to aerial parts (Amjad et al 2020;Farid et al 2017). The growth of plant roots was highly altered by Ni as compared to shoots (Antić-Mladenović et al 2017).…”

“…On the other hand, about 310 plant species have been identified as Ni hyper-accumulators as these plant species can accumulate higher levels of Ni without showing any toxic effects (Genchi et al 2020;Bhalerao et al 2015). In plant cytoplasm, usually high level of Ni was avoided by organic acids as described by Farid et al (2017) and Helaoui et al (2020).…”

Combined Citric Acid and Glutathione Augments Lead (Pb) Stress Tolerance and Phytoremediation of Castorbean through Antioxidant Machinery and Pb Uptake

“…Many HMs (e.g., Pb, copper, cobalt, nickel and cadmium) can affect plant agronomic parameters in a very toxic way [17,18]. Similarly, many researchers have reported that there is a great reduction in biomass of plants, as well as the growth of plants due to metal stress in wheat, rice and Brassica napus L. [19][20][21]. In the present study, the reduction in plant agronomic characteristics with increasing concentrations of Pb was in accordance with the work done by previous researchers [20,22,23].…”

“…Measurements were taken at appropriate wavelengths. The chlorophyll a, chlorophyll b and carotenoids wavelengths used were 644 nm, 663 nm and 452 nm with spectrophotometer (Halo DB-20/DB-20S, Dynamica Company, London, UK) and final measurements were calculated by using the following formulas [17][18][19][20][21][22].…”