Seed maturation is an important stage in a plant’s life cycle because it allows for the spatial and temporal dispersion of progeny. Storage reserve deposition, desiccation, dormancy induction, seed coat creation, and protective chemical production are all things that happen during maturity.
After the pattern construction of the embryo during maturation, the second phase of seed development,the seed reserves are synthesised.
The Maturation of Seeds:
Storage reserve deposition: The synthesis and deposition of seed storage proteins is strictly regulated in terms of both time and space; it happens only in specific tissues/organs and at specific moments throughout seed development. Following the histodifferentiation stage of seed development, cells expand and deposit reserves (including store proteins), generally in the absence of further cell divisions. Young storage parenchyma cells accumulate a variety of proteins, including storage proteins, acid hydrolases, plant defence proteins, and other reserve materials or metabolites in storage compartments (organelles), some of which are called protein bodies, during this time (particularly within the major reserve organs of seeds—the endosperm, cotyledons, or megagametophyte).
Desiccation
Desiccation tolerance is one of the most important characteristics of seeds. It is acquired late in seed development and is thought to be important for the plant’s life cycle to be completed, as an adaptation approach to ensure seed survival during storage or environmental stress, and to promote better species spread. The function of water status in dried tissues is discussed, as well as challenges with seed tolerance testing. Only in the last decade has the molecular processes of desiccation tolerance been extensively studied. Desiccation tolerance is defined as the ability to protect cellular membranes from the harmful effects of water loss and the resulting requirement to retain the bilayer structure in the absence of an aqueous environment.
Seed Dormancy Induction: Seed dormancy is a state or situation in which seeds are prevented from germinating despite the presence of favourable environmental circumstances for germination, such as temperature, water, light, gas, seed coats, and other mechanical constraints.
The fundamental cause of these circumstances is that they require a time of rest before they can germinate. These circumstances might change from day to day, month to month, and even year to year. Light, water, heat, gases, seed coverings, and hormone structures make up these circumstances.
Three types of seed dormancy have been identified.
- Endogenous sources
- Exogenous sources
- Combination
Scientists and engineers have utilised a variety of ways to break that weakens the seed coat seed dormancy.
Methods that are simple and commonly utilised are:
1)Scarification is a term used to describe any physical or chemical treatment.
When a hard seed coat imposed dormancy, such as in legumes like cajanus cajan (tur), gram, and others, the scarification technique is used.
2)Thermodynamic Treatments:
When the dormancy is caused by the embryo factor, i.e. the seed is incubated at a low temperature (0- 5o C) for 3 to 10 days over a substratum, allowing it to reach its optimum temperature. Germination necessitates the presence of this ingredient. For instance, Mustard(Brassica campestris)
3)Light Treatments:
Because the same seeds do not sprout in the dark, constant or periodic exposure to light is necessary. For example, lettuce (Lactuca Sativa) requires red light (660nm) or white light to germinate.
4)Treatments with growth regulators and other chemicals: Germination inhibitors may cause endogenous dormancy. Low levels of growth regulators (such as Gibberellins, Cytokinins, and Ethylene) may be used to break seed dormancy.
The seed coat is formed from the maternal tissue, the integuments, which originally surrounded the ovule. The mature seed coat can be a paper-thin covering (e.g. peanut), a more substantial layer (e.g. thick and hard in honey locust and coconut), or mushy, as in the pomegranate sarcotesta.
Harvest:
The optimal harvest stage and time are essential variables in the development of high-quality seeds. When the seeds are totally mature on the plant, they are usually collected. The main concept of harvesting is to let the seed to ripen on the plant for as long as possible without becoming infected or overripe.
Although each plant has an optimal period for seed collection, circumstances such as climate, weather, disease, insects, birds, and predatory animals may necessitate seed collection at a time other than the optimal one. When the crops are deemed suitable for harvesting, the plants are either chopped in half or the seeds are gathered using various methods.
Some seeds of annuals and perennials fall off the plant when they ripen, either because the fruit bursts or because of the wind. Before ripening, such seed capsules should be wrapped with muslin fabric or butter paper bags to catch the shedding seeds. Seed degradation can be caused by adverse field conditions, particularly rain during the drying phase. Extra effort is necessary in these instances, such as covering the collected seed materials before it rains or relocating them to a dry indoor location.
Flowers in floricultural crops are produced over a period of 30-60 days or even longer. Because they develop at various dates, seed harvesting occurs at distinct intervals.
Seeds are threshed after harvesting to separate the seed from the surrounding plant material. Before the seeds are threshed, they must be allowed to air dry for a length of time.
Mold, rot, and heat from decomposition will destroy the seeds if the plant material is not spread out in thin layers until it is completely dry. Seed pods may split open or lose seed when the plant material dries.
Conclusion:
The seed has three parts: an exterior seed coat that covers the seed, an endosperm that serves as a food reserve, and an embryo that is the new plant itself. A seed germinates when it is ripe and placed in a favourable environment (begins active growth).The main concept of harvesting is to let the seed to ripen on the plant for as long as possible without becoming infected or overripe.