Seed treatment with IAA-based biostimulant enhances durum wheat establishment under abiotic stress conditions

Abstract

Background: Seed treatments with biostimulants may improve crop establishment and early plant growth; however, the consistency of biostimulant responses across controlled and field environments remains unclear. Methods: This study evaluated the effects of an indole-3-acetic acid (IAA)-based biostimulant applied as a seed treatment on germination, early seedling growth, and field establishment of durum wheat. Petri dish and pot experiments were conducted under normal and NaCl-induced salinity conditions, whereas a single field experiment assessed crop establishment under low-temperature conditions and periods of excessive rainfall during early growth. Results: In the petri dish trial, seed treatment improved germination energy relative to the untreated control, indicating faster germination. Biostimulant increased plumule length, fresh weight, and vigor index by an average of 36.9%, 40.4%, and 37.8%, respectively. In the pot trial, seed treatment increased seedling length, fresh weight, and dry weight by an average of 19.9%, 37.4%, and 22.7%, respectively. Chlorophyll content index increased by 38.4%, whereas productivity loss index was lower than in the untreated control, suggesting lower biomass losses under saline conditions. Under field conditions, the biostimulant promoted faster emergence and improved crop establishment under excessive rainfall and low-temperature conditions. Plant density and tiller density increased by approximately 53% and 42%, respectively, compared with the untreated control. Conclusion: The positive responses observed across the different experiments suggest that seed treatment with the biostimulant may improve germination, early vigor, and stand establishment of durum wheat under salinity and naturally occurring early-season abiotic stress conditions.