2. Characteristics of Good Seed
The viability of the seed in the field will be determined to a large degree from its
Has a marked influence on the life and vigor of the seed. Moisture content should be less than 14% and preferably less than 12% for extended storage times.
Expresses the proportion of the total number of seeds that are alive. It is determined through controlled tests and actual counts of the number of seeds that germinate. Many varieties have a dormancy period immediately after harvest. Stored under traditional open systems the germination rate of most rice seed begins to deteriorate rapidly after 6 months.
Provides a very good estimate of the potential field performance, and subsequently, the field planting value. While the speed of germination varies slightly across varieties, seeds should imbibe (absorb) moisture and within 2 days produce a root (radicle) and the first leaf (plumule) within 4 days. At this point the seed is considered to have germinated.
The ability of the germinating seed to continue to grow and survive then determines crop establishment. Seed vigor has been defined as the sum total of those properties of the seed, which determine the level of activity and performance of the seed during germination and seedling emergence. Seed vigor is an important factor that often results in poor seedling establishment.
Seeds low in vigor generally produce weak seedlings that are susceptible to environmental stresses. Whereas, a high level of vigor in seeds can be expected to provide for early and uniform stands which give the growing seedlings the competitive advantage against various environmental stresses.