Current Agronomy

Chelate-induced accumulation of rare earth elements in plants grown on soil and ash-based growing media

Dominika Gmur, Grzegorz Siebielec, Monika Pecio — Wed, 30 Apr 2025 00:00:00 +0000

Phytoextraction is a phytoremediation technique that uses plants to remediate contaminated areas. The aim of the study was to investigate the differences between the use of two doses of chelate (5 mM and 10 mM): CA, EGTA, and EDTA on three selected plant species which grew on two substrates (soil with increased REE content, ash). The study focused on the following rare earth elements (REE) representatives: lanthanum (La), cerium (Ce), europium (Eu), and gadolinium (Gd). Three plant species were included in the study: common yarrow (Achillea millefolium L.), red clover (Trifolium pratense L.) and autumn fern (Dryopteris erythrosora (D.C.Eaton) Kuntze). The plant were grown on two substrates, the main components of which were soil with increased REE content and ash. Plant samples, divided into aboveground part and underground part, were analyzed by ICP-MS. The obtained REE concentrations in plant tissues ranged from 0.02 to 60.20 mg kg−1 (La), 0.05 to 62.22 mg kg−1 (Ce), 0.01 to 45.91 mg kg−1 (Eu), and 0.02 to 63.60 mg kg−1 (Gd). To determine the ability of plants to phytoextract REE, two factors were calculated: the translocation factor (TF) and the bioconcentration factor (BCF). The highest TF value was obtained for D. erythrosora and A. millefolium, when they were grown on substrate with ash. In the experiment, the BCF index value was not higher than 1. In general, the effect of chelates on REE accumulation was plant-specific. The application of CA resulted in the most efficient REE accumulation by plants.

Agriculturally important groups of microorganisms – microbial enhancement of nutrient availability

Małgorzata Woźniak, Sylwia Siebielec — Wed, 30 Apr 2025 00:00:00 +0000

The increased dependence of modern agriculture on excessive use of agrochemicals and mineral fertilizers, combined with the effects of climate change, will contribute significantly to environmental degradation and loss of soil quality. Consequently, current trends are based on the search for sustainable agricultural practices, in line with the pro-environmental elements of European policy, to reduce energy use and environmental problems, and to provide an adequate supply of high quality, healthy food for an ever growing world population. The production of healthy food is entirely dependent on the availability of nutrients, so the use of biofertilizers with microorganisms is one of the best ways to supplement and increase the availability of nutrients necessary for proper plant growth and yield. Microorganisms are a powerful tool that can provide significant benefits to crops for sustainable agriculture. The aim of this paper is therefore to review the literature on some of the most important groups of microorganisms that are components of biofertilisers. These are those that increase nutrient availability: atmospheric nitrogen-fixing microorganisms, phosphorus-solubilising microorganisms and potassium-solubilising microorganisms. This review therefore distinguishes between different groups of microorganisms and their plant growth promoting mechanisms by which they exert their yield enhancing function to meet the demand for healthy food. Microorganisms that are involved in balanced nutrient cycling and have other plant growth promoting properties (PGP) are an effective way to reduce the use of mineral fertilizers, enabling efficient and sustainable agriculture that maintains a healthy soil for future generations.

Effect of selected osmoprotectants (betaine, ectoine and inositol) on germination and initial growth of Triticum aestivum L. under salt stress conditions – model experiment

Karolina Furtak, Karolina Gawryjołek — Sat, 31 May 2025 00:00:00 +0000

Climate change and increasing soil degradation are driving the need for new agricultural solutions to support crops. Drought stress and salinity are major problems in fields around the world. A promising method to support plants under osmotic stress conditions is the use of exogenous osmoprotectants. In this study, the effects of three selected osmoprotectants: ectoine (0.25 mM), betaine
(25 mM), and inositol (25 mM), on germination and initial growth of spring wheat under salinity (1% NaCl) stress conditions in model experiment on Hoagland medium were determined. Addition of ectoine showed a statistically significant positive effect on wheat root length (increase of 50.4%) under control conditions. The addition of betaine showed a statistically significant positive effect on shoot length (increase of 60.2%) under salt stress conditions. Surprisingly, the addition of the ectoine to the medium resulted in a statistically significant lower fresh weight of wheat seedlings compared to the control under unstressed conditions. The results show that exogenous application of selected osmoprotectants can mitigate the adverse effects of salinity and promote growth of spring wheat, however this topic requires further, more detailed analysis.

Effect of Azotobacter salinestris on soil microbiological parameters and cucumber yield in integrated and organic farming systems

Beata Kowalska, Magdalena Szczech, Anna Gałązka, Krzysztof Zachaj — Fri, 30 May 2025 00:00:00 +0000

The aim of this study was to evaluate the effect of Azotobacter salinestris bacteria applied in the form of Rhizosum N plus preparation on the yield of cucumber cv. Gala F1 grown in organic and integrated systems. In addition, the effect of this preparation on soil microbiological parameters – Pseudomonas spp. and Azotobacter spp. number, dehydrogenases activity, biodiversity (Shannon coefficient) and microbial activity (AWCD) analyzed by BIOLOG tests – were studied.
In both cropping systems, the experiment included three treatments: control (full nitrogen fertilization); half dose of nitrogen fertilization; Rhizosum N plus preparation + half dose of nitrogen fertilization. The Rhizosum N plus formulation was applied at a rate of 25 g/ha as a spray on plants at the stage of 2–4 proper leaves. Cucumbers were harvested and segregated into the following fractions: canned, pickling and overgrown. Soil microbiological analyses and leaf analyses for Azotobacter spp. abundance were performed in three terms.
It was found that the abundance of Azotobacter sp. bacteria on cucumber leaves increased after spraying with Rhizosum N plus. The bacteria maintained a high abundance at least until 14 days after application. The preparation Rhizosum N plus had a slight effect on the increase of Pseudomonas bacteria number in the soil. No changes were found in dehydrogenases activity or in the biodiversity and functional activity of microorganisms in the soil in the treated combinations. In both cultivation systems, it was shown that the application of Rhizosum N plus had a positive effect on the yield of cucumbers. First of all, it accelerated fruit setting, which resulted in a higher yield at the first harvest. In addition, a positive effect on pickling and canning fractions was observed – a higher yield was obtained in the treatment with Rhizosum N plus + 1/2 N than in the “1/2 N fertilization” treatment.
These findings show that foliar spraying of Azotobacter salinestris in cucumber cultivation could be a sustainable way to promote plant growth and improve soil microbiological diversity.