A Different Way to Sow: Seed Enhancements Involving Gelatin Encapsulation with Controlled-Released Fertilizers Improve Seedling Growth in Tomato (Solanum lycopersicum L.)

Seed enhancements involve post-harvest modifications that improve germination and plant performance. One form of enhancement involves coatings, which encompasses encrusting, pelleting, and film coats. These coatings may contain agrichemicals, such as fungicides and insecticides, and can foster conformational changes that improve the plantability of small or irregularly shaped seeds. Seed encapsulation using pharmaceutical capsules can be viewed as an extension of seed coatings where seeds and other beneficial agrichemicals can be combined into a single plantable unit. For many crops, direct contact with high levels of conventional fertilizers may induce some level of phytotoxicity, and early studies involving fertilizer-enriched seed coatings resulted in decreased seedling emergence and diminished plant performance. Encapsulation, however, provides greater delivery volumes compared to other coatings and may offer some degree of separation between seeds and potentially phytotoxic agrochemicals. This study considered tomato seed encapsulation with controlled-release fertilizers. In general, seed exposure to gelatin-based capsules delayed germination by 2- to 3- days. Nevertheless, seed encapsulation improved plant performance including increased plant height and dry mass production by as much as 75 and 460%, respectively. These growth responses mitigated any effects attributed to germination delays. Moreover, higher levels of controlled-release fertilizers (≥800 mg) fostered earlier flower induction by up to 3 weeks. Collectively, the results suggest that seed encapsulation can be an effective way to deliver fertilizers to plants in a manner that could reduce overall fertilizer application rates and possibly lessen the quantity of plant nutrient input necessary for tomato cultivation.