Advance in judgment methods of seed optimum harvest time

Judgment of seed optimum harvest time has important significance to high quality germplasm resource conservation, utilization and development. This study presented several methods that can judge the optimum seed harvest time according to the seed morphological changes (seed color and weight) and mature state (growth period and loss situation after seed maturation such as seed shedding and shattering), physiological changes within the seeds (water content, electric conductivity, germination index, inclusion and stress resistance) and some other index (growing degree days and synthetic judgment index). Further studies in this fields and issues that might be occurred are also addressed in the paper.