Implications of seed dormancy in seed longevity and storability

Seed dormancy:

Seed dormancy is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival. It can also be defined as the state or a condition in which seeds are prevented from germinating even under the favorable environmental conditions for germination including, temperature, water, light, gas, seed coats, and other mechanical restrictions. The main reason behind these conditions is that they require a period of rest before being capable of germination. These conditions may vary from days to months and even years. These conditions are the combination of light, water, heat, gases, seed coats, and hormone structures

Implications of seed dormancy in seed longevity and storability:

Two major characteristics that control seed quality are seed dormancy and seed longevity (storability). Seed dormancy can be seen as a survival mechanism of plants, to avoid seed germination at moments that do not allow the plant to complete its life cycle. Seed companies apply laborious and costly priming techniques to overcome seed dormancy and speed up and synchronize seed germination. However, priming is a pre-germination treatment, which may lead to a substantial reduction of seed longevity. Apart from high levels of seed dormancy also the complete lack of seed dormancy causes problems, this leads to pre-harvest sprouting. This is a problem for example in tomato and (sweet) peppers where the seeds already germinate within the fruits. Knowledge on the genetic control of dormancy and seed longevity is essential to breed varieties that have the required level of seed dormancy but that are storable for longer times, so that priming is not necessary or that less laborious “priming” techniques can be applied and problems with storability can be avoided. Three of the positions that affect seed dormancy co-locate with positions that control seed longevity. It is very important to know if these two seed traits are regulated by the same genes, as most companies are aiming for low levels of seed dormancy and long seed longevity. Seed dormancy mainly prevents the seed from germinating in the field before harvesting or immediately after harvesting which facilitates the storage of seed for a long period of time.

Seed longevity helps to enhance the viability percentage of the seed. Seed dormancy occurs naturally so that early germination isn’t happening there and we can sow seeds for the next season/year. If longevity is more, then only the longer storability is possible . The dormancy period depends upon the nature of the crops. For example; pepping of buds occurs 2 to 4 weeks before defined loss of dormancy likewise temperate crops such as wheat, etc get matured only going after dorm any period. There is the formation of embryo structure but the enzymes necessary for germination aren’t accumulated and in that period the photosynthetic process occurs and we can keep it on dormancy. So, this mechanism is a good method to increase the longevity of the seed. By increasing longevity, we can prolong seed storability. The seed remains alive in the soil for many years due to dormancy. It helps in the dispersal of seeds through adverse environmental conditions. During seed storage, seed respiration uses many biomolecules (i.e.oils, fatty acids, glucose, etc.)so that seed germination rate and seedlings’ establishment declines by which ultimately reduces seed longevity. Seed loses its vigor, viability, and quality of seed get decay. So, it should be carefully checked before storage. If seed loses its vigor; can’t germinate. So, we can conclude dormancy is co-related with storability and longevity. Although seeds are inanimate creatures, they are alive and metabolically active. In the soil, most weed species persist in a moist condition and are capable of metabolic repairs. Eventually, however, damage to membranes, genetic mistakes, toxins, and other metabolic problems cause loss of vigor and eventual death. This happens most quickly at warm temperatures and when the seeds are nearly but not completely dry. Since both of these conditions are most likely to occur near the soil surface, seeds near the surface that remain dormant are in a risky position.

Conclusion:

Seed dormancy is a very important parameter for food security in Nepal. Because high amounts of produce are stored for a long time and seed storability helps to obtain an adequate amount of food in season. There is no crisis of food in season. Everybody has to eat and our ultimate goal is also to save our country from hunger by being self-dependent, not dependent on neighboring countries for food. Thus dormancy of seed can be considered as the major agent that determines the longer storability of seed for a longer period of time.

Writer: Netra Prasad Pokharel (Student, Bsc Ag 4th semester, IAAS, Paklihawa)