Many farmers know from experience that seed of same lots may emerge from the soil quite differently, resulting in erratic field stands, replanting (on some occasions), or both. Vigorous seeds will produce excellent emergence and stands in proper soil environment. It can improve the chances for satisfactory emergence. Advanced stages of seed deterioration are evidenced by visible symptoms during germination and seedling growth. However, these are preceded by more subtle physiological changes whose symptoms can be detected only by sophisticated measurement techniques. Quality seed is
defined as varietally pure with a high germination percentage, free from disease and disease causing organisms, and with a proper moisture content and weight. Vigour is often implied when discussing seed quality and most growers have to use the terms quality and vigour interchangeably. Seed vigour comprises those properties, which determine the potential for rapid uniform emergence and development of normal seedlings under a wide range of field conditions (ASPB, 2003). Seed vigour is generally related to yield in vegetables.