"On-off" thermoresponsive coating agent containing salicylic acid applied to maize seeds for chilling tolerance

• Published in: PloS one Vol. 10; no. 3; p. e0120695
• Main Authors: Guan, Yajing, Li, Zhan, He, Fei, Huang, Yutao, Song, Wenjian, Hu, Jin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.03.2015; Public Library of Science (PLoS)
• Subjects: Acids; Acrylamides - pharmacology; Biochemical Phenomena - drug effects; Biotechnology; Chemical synthesis; Chilling; Coating effects; Coatings; Cold Temperature; Cooling; Corn; Enzymatic activity; Germination; Germination - drug effects; Germination - physiology; Hydrogel, Polyethylene Glycol Dimethacrylate - pharmacology; Hydrogels; Isopropylacrylamide; Load resistance; Malondialdehyde; Malondialdehyde - pharmacology; Oxidative stress; Phase transitions; Phenols (Class of compounds); Physiological Phenomena - drug effects; Physiological Phenomena - physiology; Physiology; Plant growth; Polyamines; Polymerization; Polymers; Protective coatings; Salicylic acid; Salicylic Acid - pharmacology; Science; Seed germination; Seedlings; Seedlings - drug effects; Seedlings - physiology; Seeds; Seeds - drug effects; Seeds - physiology; Signal transduction; Stress, Physiological - drug effects; Stresses; Temperature effects; Transition temperature; Transition temperatures; Zea mays; Zea mays - drug effects; Zea mays - physiology; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0120695

Chilling stress is an important constraint for maize seed establishment in the field. In this study, a type of "on-off" thermoresponsive coating agent containing poly (N-isopropylacrylamide-co-butylmethacrylate) (Abbr. P(NIPAm-co-BMA)) hydrogel was developed to improve the chilling tolerance of coated maize seed. The P(NIPAm-co-BMA) hydrogel was synthesized by free-radical polymerization of N-isopropylacrylamide (NIPAm) and butylmethacrylate (BMA). Salicylic acid (SA) was loaded in the hydrogel as the chilling resistance agent. SA-loaded P(NIPAm-co-BMA) was used for seed film-coating of two maize varieties, Huang C (HC, chilling-tolerant) and Mo17 (chilling-sensitive), to investigate the coated seed germination and seedling growth status under chilling stress. The results showed that the hydrogel obtained a phase transition temperature near 12°C with a NIPAM to MBA weight ratio of 1: 0.1988 (w/w). The temperature of 12°C was considered the "on-off" temperature for chilling-resistant agent release; the SA was released from the hydrogel more rapidly at external temperatures below 12°C than above 12°C. In addition, when seedlings of both maize varieties suffered a short chilling stress (5°C), higher concentrations of SA-loaded hydrogel resulted in increased germination energy, germination percentage, germination index, root length, shoot height, dry weight of roots and shoots and protective enzyme activities and a decreased malondialdehyde content in coated maize seeds compared to single SA treatments. The majority of these physiological and biochemical parameters achieved significant levels compared with the control. Therefore, SA-loaded P(NIPAm-co-BMA), a nontoxic thermoresponsive hydrogel, can be used as an effective material for chilling tolerance in film-coated maize seeds.