The presence of such substances assumes critical characteristics under certain ambient conditions, therefore they define the survival of the species. The hormonal inhibitor more known, and probably the only one is the acid abcsico (AAb). The no-Hormonais inhibitors show different chemical characteristics, being able to be acid organic (mlico, citric, ascetic, tartaric), which occur in fruits, in enough high levels to inhibit the germination of the seeds. Treatments with certain chemical substances and daily pay-cooling have been efficient in the promotion of the germination of seeds of some species. Beyond the giberelinas, other substances have shown resulted similar on the germination as, for example, variations in the level of free and conjugated citocininas in embryos of some vegetal species. It is possible that the activity of the citocininas, during the germination, is related with the growth of radcula.

The period of ' ' rest fisiolgico' ' or latency is changeable in accordance with the vegetal species and the ambient conditions which the seed remain displayed. When a seed is humidified, active a series of metabolic processes that can determine the retaken one of the development of the embryo, since that the suppliment of oxygen and the temperature are favorable. Species exist exactly that the process does not have continuity, when the seeds are placed under supposedly favorable environment conditions, because they possess mechanisms chokes of the sequence of necessary metabolic events for the retaken one of development of the embryo (Ministry of Agricultura and the Agrarian Reformation, 1992). In this way, in accordance with Son et al. (1987), seeds that do not present growth of the embryo, under pparently favorable environment conditions, are called dormentes. The dormncia, therefore, mentions the period of latency determined for factors or endogenous characteristics to it. On the other hand, the quiescentes seeds present normal intrinsic conditions and remain in ' ' rest fisiolgico' ' due to absence of favorable conditions of the environment (examples: inadequate suppliment of water and favorable temperature).