Enhancing Cadmium Tolerance and Pea Plant Health through Enterobacter sp. MN17 Inoculation Together with Biochar and Gravel Sand

Abstract

Contamination of soils with heavy metals, particularly cadmium (Cd), is an increasingly alarming environmental issue around the world. Application of organic and inorganic immobilizing amendments such as biochar and gravel sand in combination with metal-tolerant microbes has the potential to minimize the bioavailability of Cd to plants. The present study was designed to identify the possible additive effects of the application of Enterobacter sp. MN17 as well as biochar and gravel sand on the reduction of Cd stress in plants and improvement of growth and nutritional quality of pea (Pisum sativum) plants through the reduction of Cd uptake. Pea seeds were surface sterilized then non-inoculated seeds and seeds inoculated with Enterobacter sp. MN17 were planted in artificially Cd-polluted soil, amended with the immobilizing agents biochar and gravel sand. Application of biochar and gravel sand alone and in combination not only improved the growth and nutritional quality of pea plants by in situ immobilization but also reduced the uptake of Cd by plant roots and its transport to shoots. However, microbial inoculation further enhanced the overall plant health as well as alleviated the toxic effects of Cd on the pea plants. These soil treatments also improved rates of photosynthesis and transpiration. The combined use of biochar and gravel sand with bacterial inoculation resulted in an increase in plant height (47%), shoot dry weight (42%), root dry weight (57%), and 100 seeds weight (49%) as compared to control plants in Cd contaminated soil. Likewise, biochemical constituents of pea seeds (protein, fat, fiber, and ash) were significantly increased up to 41%, 74%, 32%, and 72%, respectively, with the combined use of these immobilizing agents and bacterium. Overall, this study demonstrated that the combined application of biochar and gravel sand, particularly in combination with Enterobacter sp. MN17, could be an efficient strategy for the remediation of Cd contaminated soil. It could support better growth and nutritional quality of pea plants.

The interactive effect of pH variation and cadmium stress on wheat (Triticum aestivum L.) growth, physiological and biochemical parameters

“…Low, moderate, and high Cd 2). However, neutral pH (7) significantly reversed the toxicity of Cd in wheat seedlings by improving growth and leaf area, chlorophyll and carotenoids contents, macro, and micronutrients availability, enzymatic and non-enzymatic antioxidative defense systems activities, declining Cd contents, MDA, H 2 O 2 , and EL contents as compared to both acidic (5) and alkaline pH (9). These results are in line with former findings [10-12, 41, 42].…”

“…This damage of fatty acids in the membrane due to electrolytic leakage eventually destabilized the membrane. It is concluded from recorded results that neutral to alkaline pH (7 to 9) under Cd-induced oxidative stress plays a crucial role in stabilizing membranes by reducing EL values compared to acidic pH (5).…”

Biochar Mediated-Alleviation of Chromium Stress and Growth Improvement of Different Maize Cultivars in Tannery Polluted Soils

“…Moreover, enhanced EL in this study might be associated to excessive ROS formation by Cr stress. However, the application of biochar resulted in increased RWC and decreased EL, which might be associated to enhanced availability of essential plant nutrients and improved water holding capacity [ 32 , 52 , 119 ]. The increased RWC and decreased EL, thus, helped to better sustain maize cultivars under Cr stressed environments [ 15 , 120 ].…”

“…Moreover, biochar could enhance supply of proton to reduce Cr (VI) into its less toxic Cr (III) form [ 47 , 48 , 49 ]. Many researchers have previously described the biochar potential to improve the soil characteristics and nutrient uptake by plants, especially under pollutant stress conditions [ 50 , 51 , 52 ]. Only a limited literature is available on physiological as well as biochemical responses of maize cultivars to biochar applied in soil polluted with indigenous tannery waste [ 12 , 47 , 53 ].…”

Influence of Selenium on Growth, Physiology, and Antioxidant Responses in Maize Varies in a Dose-Dependent Manner

“…However, improvement in these parameters, which are mentioned above, was also noticed at lower Se levels (2.5 mg kg −1 ). Low levels of Se may help in protecting chlorophyll enzymes which then improve the chlorophyll content [35]. Higher selenium concentration reduces net photosynthetic rate (A), which ultimately leads to a reduction in biomass production.…”