Soil salinity is a global problem, which is predicted to worsen in arid and semi-arid regions due to climate change. The aim of this study was to understand the remediation potential of biochar in alleviating salt stress by studying its effects on the growth and physiological parameters of the tomato (Solanum lycopersicum). A completely randomized design (CRD) was used where three different biochar doses (0%, 5% (v/v), and 10% (v/v)) were applied to the soil under saline (100 M) and non-saline conditions. Our results showed that while salt stress affected the plant growth negatively at all biochar doses, 5% and 10% biochar applications improved the overall plant performance under saline conditions. For the samples with salt stress, plant height and leaf area were increased by 43.1% and 45.3%, respectively, and physiological parameters, such as leaf relative water content and chlorophyll-a content, increased when 5% biochar was used. On the other hand, the highest increase rates in shoot fresh weight (113.7%), shoot dry weight (74.8%), the number of leaves (24.9%), root fresh weight (115.5%), root dry weight (62.5%) were obtained from 10% biochar amendment under saline conditions. Moreover, biochar amendment at both doses significantly decreased the superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities, as well as malondialdehyde (MDA) and proline contents, which resulted in an improved plant growth due to the reduction of the oxidative and osmotic stresses. In conclusion, biochar amendment might be a promising approach to mitigate the adverse effects of salinity stress on tomato seedlings

The objective of this study was to determine the effect of 24-epibrassinolide (24-EBL) applications on growth, chlorophyll, and mineral content of lettuce ( Lactuca sativa L. var. Crispa) grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Lettuce seedlings were treated with seed and foliar 24-EBL applications at different concentrations (0, 1, 2, and 3 μM). Salinity treatments were established by adding 0, 50, and 100 m m of sodium chloride (NaCl) to a base complete nutrient solution. Results showed that salt stress negatively affected the growth and mineral content of lettuce plants. However, seed and foliar applications of 24-EBL resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher stem diameter than the control under salt stress. Salinity treatments induced significant increases in electrolyte leakage of plant, but foliar 24-EBL application reduced leaf electrolyte leakage and has determined lower values of leaf electrolyte leakage than non-treated ones. In regard to nutrient content, it can be inferred that 24-EBL applications increased almost all nutrient content in leaves and roots of lettuce plants under salt stress. Generally, the greatest values were obtained from 3 μM 24-EBL application. Treatments of 24-EBL alleviated the negative effect of salinity on the growth of lettuce.

Iron deficiency, which severely decreases the plant yield and quality, is one of the major problems of calcareous soils. Foliar applications of humic substances and/or Fe fertilizers are environmentally friendly methods to cope with Fe deficiency. The aim of this study was to investigate the combined effect of Fe/nano Fe and humic/fulvic acid-based biostimulant foliar applications on the Fe content and plant growth parameters of spinach. Treatment solutions were prepared either by mixing a common Fe fertilizer, FeSO₄·7H₂O, with different commercial biostimulants (Fulvic-based: Fulvagra^®, Fulvagra^®WSG; Humic-based: HS300^®, Humin Fe^® and Liqhumus^®, Grevenbroich, Germany) or by mixing nano ferrihydrite with different ratios of fulvic substance (FA-50, FA-75, and FA-100) and humic acid (Nano Iron). Growth parameters (plant fresh and dry weights, plant dry matter, root fresh and dry weights, root dry matter, leaf number per plant, and leaf area); chlorophyll reading value (SPAD); chlorophyll (a,b, and total) and carotenoid contents; and leaf and root mineral contents (N, P, K, Ca, Mg, S, Cu, Mn, Zn, B, active Fe, and total Fe) of samples were determined. Our results showed that foliar application of biostimulants together with Fe sources improved the nutrient uptake, chlorophyll contents, growth characteristics, and yield; however, not all humic substances had the same effect. When all parameters were considered, Fulvagra treatment—which contained 17% fulvic acid and microorganisms in its content together with 20 mM FeSO₄·7H₂O—was the most effective application, followed by FA100 treatment containing fulvic acid and 20 mM nano ferrihydrite. This finding indicates that fulvic acid containing biostimulants is more effective in foliar applications than humic-based biostimulants against Fe deficiency due to their low molecular weight which enables better penetration into the leaves. In conclusion, foliar applications of fulvic substances together with Fe fertilizers can be used to increase the Fe uptake of crops and the yields under Fe-deficient conditions.

Peat is a spongy substance which is an effect of incomplete decomposition of plant residues in different stages of decomposition. Between the several organic matters which are used as substrate for horticultural plants cultivation in soilless conditions, peat is the unabandonable ingredient for mixtures for commercial production of plants. Peat is used in horticulture as a component of garden plant substrates, in agriculture for the production of garden soil and as an organic fertilizer, and in balneology as a material for baths and wraps. The use of peat for agriculture and horticulture is determined by the following quality parameters: the degree of decomposition, ash content, pH, the presence of carbonates, the density of the solid phase, bulk density, and porosity. As an organic material, the peat forms in the acidic, waterlogged, and sterile conditions of fens and bogs. The conditions seem like the development of mosses. The plants do not compose as they die. Instead of this, the organic matter is laid down and accumulates in a slow time as peat due to the oxygen deficiency in the bog. This makes peat a highly productive growing medium. In the present novel review, we discuss the peat use in horticulture.

Salinity causes yield and quality losses in agricultural production and therefore great economic losses around the world. Hydrogen sulfide (H₂S) is known to play a crucial role to ease physiological and metabolic processes in plants, and also increases the tolerance of the plant against many abiotic stress conditions. In this study, we investigated the effects of H₂S treatments (0, 25, 50, 75 and 100 µM NaHS were applied as H₂S donor) to the tomato seedlings to alleviate the harmful effects of salt stress (0, 75 and 150 mM NaCl). There was a significant decrease in plant growth and development in parallel with the increased salt level. Visible changes in plant development were observed after the dose of 75 mM NaCl in the tomato seedling. The effects of different doses of exogenous H₂S treatment were found to be significant. H₂S treatment increased the stress tolerance in tomato seedlings by arranging the mineral element and hormone content. Furthermore, H₂S relieved the effect of stress in plants by increasing photosynthetic activity (photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductivity (gs) and intercellular CO₂ concentration (Ci)) of the plant. In addition, the effect of H₂S on salt stress tolerance in tomato seedlings may be due to its positive effect on mineral element contents. As a result, based on the beneficial effects of H₂S in tomato seedlings under salt stress, this treatment can be considered as an alternative resilience method for cultivation in saline soils or irrigation with low quality waters.

This study investigated the interactive effects of drought stress with biochar on plant growth, the physiological and biochemical attributes of soybean seedlings. A pot trial tested the effect of amending a loamy sandy soil with biochar at three doses: 0%, 3% and 6% in the alleviation of drought stress, imposed by adjusting soil moisture content at three levels (in terms of soil field capacity, FC): 100% FC, 75% FC and 50% FC. Water deficit negatively influenced the growth of soybean seedlings and chlorophyll content of leaves, particularly in non‐amended plants whereas biochar amendment boosted the growth and chlorophyll content, particularly under drought stress. Drought stress elevated malondialdehyde (MDA), hydrogen peroxide (H ₂ O ₂ ), proline, sucrose and abscisic acid (ABA) contents as well as the antioxidant enzyme activity [peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD)] of soybean leaves but reduced the contents of indole acetic acid (IAA) and gibberellic acid (GA); biochar amendment counteracted the impact of drought. The findings of the study indicate that biochar amendment can enhance soybean growth by modulating the plant physiology and biochemistry under drought stress.