Seed Technology and Seed Enhancement

This paper reviews the uses, properties and manufacture of the main array of ‘seed enhancement technologies’ that are implemented in current commercial practice, with a particular emphasis on cultivated horticultural and ornamental species. Recent developments, as well as some of the newer technical approaches that are still in the research or at an early commercial stage, are covered. Coating technologies - pelleting, encrusting and filmcoating - are now used increasingly widely to facilitate seed planting, by altering seed shape, weight and surface texture, improving seed-soil contact, or manipulating imbibition. They are also used to deliver materials such as micronutrients and crop protection agents, including the high-dose systemic insecticides. New pellet manufacturing techniques, using rotary coaters, have provided an alternative to traditional ‘pan coating’. Hydration treatments manipulate vigour or physiological status, such as by priming, steeping, and pregermination. These treatments are used to make germination and seedling growth more rapid and synchronous in the seedbed in the open field or in protected conditions, and better tolerate environmental stresses. Both priming and coating technologies can also deliver beneficial microorganisms from seeds to crops. Organic farming market standards are stimulating the evaluation and optimization of methods to produce healthy planting material and new seed sanitation treatments as alternatives to fungicides or conventional hot water or bleach treatment while retaining seed viability in storage. Sorting on the basis of colour, X-ray analysis of internal structures or buoyant density in solvents offer the ability to remove weak or dead seeds, and hence ‘upgrade’ seedlot quality.