Seed Dormancy: A Review on Importance, Dormancy Types and Elimination Methods, with Emphasis on the Trend of Seed Dormancy Research in Iran

Seeds need successful germination at the optimal time and conditions to survive. Sometimes, even in the best environmental and genetic conditions of the seed, they do not germinate or germinate with a delay, which are called dormant seeds. Seed dormancy can have positive effects on avoiding adverse conditions and ensuring survival in the environment. However, dormancy in crop plants reduces emergence and yield by preventing germination. A combination of environmental and seed genetic factors are involved in seed dormancy formation. In general, seed dormancy includes: physical dormancy, physiological dormancy, morphological dormancy, morphophysiological dormancy and combinational dormancy, and physical / chemical scarification treatments, hot and cold stratification, leaching, hormonal treatments, after-ripening, light and combination treatments can be used to eliminate dormancy depending on its type. Therefore, in this study, using domestic studies conducted in the field of seed dormancy in different plant species, identification of dormancy in different plant species and its types have been discussed, and general and practical information in this regard has been provided.

In this study, 168 reports published on 250 plant species in the last 20 years, which were published in the seed dormancy of medicinal plants, weeds, rangelands, ornamentals and crops were investigated. Then, the percentage of plants studied and their families, as well as the share of different types of seed dormancy and appropriate treatments to for its eliminate were determined.

Among the plant species studied, the most freuqent type of dormancy was related to physiological dormancy (50%), followed by physical dormancy, combinational dormancy, morphophysiological dormancy and the lowest share of dormancy in the studied plant species was related to morphological dormancy (1.61%). The most effective treatments to eliminate physiological dormancy were the use of cold stratification, gibberellic acid, and potassium nitrate. Also, the most effective treatments for the removal of physical dormancy were the use of physical / mechanical scarification treatments, chemical scarification and potassium nitrate treatment. According to the results, temperature treatments and then gibberellic acid and potassium nitrate treatments are recommendedt eliminate morphological dormancy. To eliminate morphophysiological dormancy, it is recommended to use treatments to maturate differentiated small or undifferentiated seeds (removal of morphological dormancy) as well as treatments to counteract the germination inhibitory factors or to compensate the were applied the most to eliminate morphophysiological dormancy.

By identifying the type of dormancy and applying the appropriate treatments, the germination of economical and valuable plants can be improved.