Priming and Coating Seeds with Humic Acid as an Effective Strategy in the Integrated Management of Salt-Affected Soils

Atefeh Rashidifard

Objective: Salinity is a major abiotic stress reducing crop yield and quality worldwide. This review systematically evaluates the effectiveness of seed priming and coating with humic acid (HA) as a strategy to improve germination, seedling establishment, and plant growth under salt stress.
Method: A comprehensive literature search was conducted in major scientific databases (Web of Science, Scopus, Google Scholar) using relevant keywords. Studies investigating physiological, biochemical, and molecular mechanisms of HA-mediated salt tolerance through seed priming and coating were reviewed.
Results: Seed priming and coating with humic acid significantly improved germination percentage and rate, increased root and shoot growth, and enhanced chlorophyll content and photosynthetic efficiency under salinity. HA reduced Na⁺accumulation, improved K⁺/Na⁺ ratio, and increased activity of antioxidant enzymes (SOD, CAT, POX). It also promoted ATP production and facilitated uptake of essential nutrients (K⁺, Ca²⁺, Mg²⁺).
Conclusions: Seed priming and coating with humic acid is an effective, low-cost, and environmentally friendly approach to enhance salt tolerance in crops. It accelerates seedling establishment, stimulates root growth, and reduces oxidative stress by boosting antioxidant enzyme activity. Future research should focus on synergistic effects with other biostimulants across different crops and salinity levels.

Highlights

Priming and coating seeds with humic acid boosts plant tolerance to salinity stress.
Humic acid improves soil health and nutrient efficiency sustainably.
Priming and coating seeds with humic acid is a cost-effective method for boosting crop growth and yield in salt-affected soils.

The Effect of Silicon Seed Priming on Germination and Biochemical Indices of Maize (SC 704) Across Different pH Ranges

Mohammad Sedghi

Objective: This study aimed to investigate the effects of seed priming with silicon on germination and biochemical responses of maize (Zea mays L. SC 704) under different pH levels of the growth medium.
Method: The experiment was conducted as a factorial arrangement within a completely randomized design (CRD) with three replications. Treatments consisted of four priming levels: control (distilled water) and silicon (as sodium silicate) at concentrations of 50, 100, and 150 mg L^-1, and three pH levels of the growth medium (5, 6.5, and 8). The measured traits included germination indices (percentage and rate), seedling growth (fresh weight, vigor weight, and length), ion leakage (relative electrolyte leakage, REL), and biochemical indices (activities of α-amylase and protease, soluble sugar content, total protein, and silicon uptake)
Results: Deviation from the optimal pH (6.5) toward acidic (pH 5) or alkaline (pH 8) conditions significantly reduced germination and growth indices while increasing ion leakage. Seed priming with silicon, particularly at 150 mg L^-1, markedly mitigated the adverse effects of pH changes. Under acidic conditions (pH 5), this treatment increased germination percentage by 63.19% compared to the non-silicon control at the same pH, reduced relative electrolyte leakage (REL), and significantly enhanced α-amylase and protease activities, soluble sugar content, total protein, and silicon uptake. The interaction between silicon and pH was significant only for germination rate, highlighting the specific role of silicon in accelerating germination under unfavorable pH conditions.
Conclusions: Seed priming with silicon at 150 mg L^-1 effectively enhances germination capability and reinforces the physiological and biochemical status of maize seeds under non-optimal pH conditions, particularly acidic stress. This approach holds significant promise for improving field establishment in soils with suboptimal pH.

Highlights

Silicon priming improved germination, rate and vigor at all pH levels, especially pH 5.
Silicon (150 mg L^-1) reduced electrolyte leakage and membrane damage under pH stress.
Silicon enhanced α-amylase, protease, soluble sugars and total protein in seedlings.
Silicon benefits were pH-independent, ensuring robust stress alleviation during germination.

Iranian Journal of Seed Research

Priming and Coating Seeds with Humic Acid as an Effective Strategy in the Integrated Management of Salt-Affected Soils

The Effect of Silicon Seed Priming on Germination and Biochemical Indices of Maize (SC 704) Across Different pH Ranges