Hydrophilic polymer film coat as a micro-container of individual seed facilitates safe storage of tomato seeds

• Hydrophilic polymer coat acts as moisture barrier and maintains the seed quality.
• Hydrophilic polymer coat in contact with free water forms a mucilage mass around the seed, which facilitates faster imbibition and germination.
• Hydrophilic polymer coating was found to be a better alternative to regulated environment seed storage.

In high-value, low-volume crops like tomato, the high seed multiplication ratio and low seed rate often leads to large quantity of carry over seeds. Seeds lose viability over time, which manifests in poor crop establishment in the field. Hydrophilic polymer seed coating has been examined for better crop establishment and as a delivery system but has not been investigated as a means to maintain seed quality during storage. Hence, the present study was undertaken to investigate the use of hydrophilic polymer (Disco Clear) film coating as a tool for ensuring safe seed storage. Seed moisture kinetics under saturated atmospheric conditions revealed lower moisture adsorption and desorption pattern in hydrophilic polymer-coated seeds as compared to non-coated seeds. However, when exposed to freely available water, hydrophilic polymer facilitated faster and more controlled imbibition, which manifested in reduced mean germination time. Seeds coated with hydrophilic polymer maintained the quality over a longer storage period than non-coated seeds, irrespective of the packaging material and storage conditions. In polymer-coated seeds that were stored in paper bags under ambient room conditions, non-significant differences were observed for all the observed seed quality parameters for longer period thereby indicating its practical application as an alternative to storage under regulated environment. The presence of the hydrophilic polymer film coat acted as a physical barrier for absorption of moisture in the vapour phase and hence, under ambient conditions, the film coated seeds remained effectively protected from equilibration with fluctuating relative humidity, in a manner comparable with storage in moisture impervious containers. Considering this fact, we propose that the polymer film coat in itself acts as a micro-container for seed and thereby facilitates safe seed storage for an extended length of time.