Effects of Heavy Metal-Tolerant Microorganisms on the Growth of “Narra” Seedlings

Abstract

The effectiveness of heavy metal-tolerant microorganisms for supporting plant growth needs to be understood before it can be used as a soil bioremediation agent. The purpose of this study was to determine the effect of heavy metal tolerant microorganisms on the growth of “Narra” seedling (Pterocarpus indicus Wild). Three heavy metals-resistant (Pb, Cd, and Cu) rhizobacteria from a copper (Cu) mined-out site in Marinduque, Philippines showed plant growth promotion in vitro. A treatment combination of formula inoculant A (CuNFbM 4.1, MGR 333), B (CuNFbM 4.1, MGR 333, PbSM 2.1), and O (Uninoculated); compost (0%, 4%); and lime + inorganic fertilizer {without or with lime and inorganic fertilizer (LF0; LF1)} were applied to Narra seedlings planted on 445 mg/kg Cu-contaminated soil. Lime (2 mg/ha) and the recommended dose of soybean inorganic fertilizer were used as positive controls to evaluate the ability of inoculations and composts to promote the growth and used as positive controls to evaluate the ability of inoculants and composts to promote the growth and copper accumulation of narra in greenhouse experiments. All treatment combinations resulted in significant differences in plant height, leaf number, stem diameter, shoot and root dry weight, as well as, shoot, root Cu content, and plant Cu uptake of 13-week-old “Narra”. Inoculated “Narra” could thrive better in mine-degraded soil containing 445 ppm Cu with 4% compost. Inoculant B demonstrated the best plant performance while Pseudomonas synxantha (PbSM 2.1) probably increases the plant’s growth due to 1-aminocyclopropane-1-carboxylate (ACC) deaminase it produces. Accumulation of Cu was higher in the root compared other plant parts. More research is necessary to elucidate the mechanism of plant growth promotion and heavy metal re mediation by P. synxantha.

Shallot growth and production responses to application of microorganisms based-biostimulant and NPK fertilizer combinations on acid soil

“…The soil samples at Kp. Kentrong, Malangsari Village, Cipanas District, Lebak Regency, Banten Province were taken, handled, and prepared as explained before [19].…”

“…Soil characteristics of the bulk soil sample, including texture, pH, C-organic, N-Kjeldahl, a 25% HCl extracted P and K, available P (Bray 1/Olsen), and K (Morgan), cation exchange value (Ca, Mg, K, Na), NH4OAc 1 N pH 7 extracted CEC, base saturation, Al3 + , H + , and total heavy metal (Pb, Cd, and Cu) used data from the previous study [19].…”

“…Plants need sufficient and balanced nutrient elements and efficient fertilizer application (time, shape, dose, and appropriate method) to increase plant growth and productivity [34]. Moreover, organic material was an energy source for soil-beneficial microorganisms around the roots for their multiplication and functions in plant growth promotion activity [19].…”

Exogenous application of citric acid alleviates copper-induced stress in Withania coagulans (Dunal)

“…The corresponding triplicate of each treatment was pooled together to obtain a composite sample of each treatment. Assessment of agronomic traits: Plant agronomic attributes (number of leaves, lengths of root and shoots, and fresh and dry weights) of the plant were computed (Yuniarti et al, 2022). Estimation of photosynthetic pigments: Crushed fresh leaves (0.5 g) with pestle and mortal from each treatment to calculate the amounts of chlorophyll-a, b, and carotenoids.…”