The Importance of Salicylic Acid, Humic Acid and Fulvic Acid on Crop Production

Biostimulants are one of the most important substancesfor improving productivity, growth and yield of plants as well as heavy metal detoxification, and stimulating natural toxins, controlling pests and diseases and boosting both water and nutrient efficiency. Google Scholar, Science Direct, CAB Direct, Springer Link, Scopus, Web of Science, Taylor and Francis, and Wiley Online Library have been checked. The search was done to all manuscript sections according to the terms "Salicylic acid," "Humic acid," "Fulvic acid," "Biostimulants" and "Plant growth promotion." On the basis of the initial check, Titles and Abstracts were screened on the basis of online literature, and then articles were read carefully. Salicylic acid may have important roles in abiotic stresses such as salinity, drought, cold, heavy metal and heat stresses, and it has been considered an important environmentally-sound agent with tremendous economical benefits and rapid responses. The positive effects of the application of salicylic acid have been reported in crops such as ajwain, alfalfa, anthurium, artemisia, artichoke, barley, bean, black mustard, broad bean, chickpea, chicory, canola, coriander, corn, cotton, cucumber, cumin, fennel, fenugreek, goji, longan, milk thistle, millet, onion, pea, pepper, pistachio, radish, rice, rosemary, rye, safflower, saffron, savory, sorghum, soybean, spinach, strawberry, sugar beet, tomato, wheat, etc. Humic acid can improve and stimulate plant growth and yield, suppress diseases and promote more resistance to stresses. Fulvic acid can increase root system and promote seed germination, growth rate and final yield. The present manuscript highlights the most important impacts of salicylic acid, humic acid, and fulvic acid, emphasizing their roles in modern sustainable crop production.