Parthenocarpy refers to the process through which fruits are developed without fertilization of ovules and may be seedless or partly seedless fruits.
In regular fruit development, fertilization occur when the male gametes (pollen) fuse with female gametes (ovules) to form seed as well as fruit tissue. Parthenocarpy, on the other hand, is where the ovary of the flower grows into a fruit without being subjected to fertilization. This can occur naturally in some plants or be artificially induced through the application of plant growth regulators such as auxins, gibberellins, or cytokinins, as well as through genetic engineering or environmental influence.
It is widely applied in agriculture to produce desirable seedless varieties of fruits like bananas, cucumbers, and grapes. It also serves as a solution for regions with unfavorable pollination conditions, improving crop yields and fruit quality. Thus, parthenocarpy is a significant tool in responding to the growing demand for seedless fruits while solving challenges like declining populations of pollinators and climate change.
Types of parthenocarpy
Natural parthenocarpy
It refers to the natural spontaneous development of fruits without undergoing fertilization; in some species, this development happens naturally in the plant species. The growth of the flower ovary develops a fruit independently, with no interference of pollination and no fusion of male and female gametes that finally lead to the production of seedless or partly seedless fruits.
Natural parthenocarpy is exhibited by plants like bananas, pineapples, figs, and some types of oranges and grapes. The key advantage of natural parthenocarpy is that it is independent of pollinators, which allows plants to produce fruits in environments where the conditions for pollination are unfavorable or where pollinators are scarce.
Artificial parthenocarpy
The induced seedless development of fruit without fertilization by artificial means is called artificial parthenocarpy.
This method is widely practiced in agriculture in order to produce commercially required seedless fruits.
Auxins and gibberellins are applied as plant hormones that mimic the natural signals initiated by fertilization, thus causing the ovary to grow into fruit. Genetic engineering allows for seedless fruits without the need for any exogenous treatments. Parthenocarpy can also be induced through environmental means such as temperature control or even the physical manipulation of flowers.
Benefits of parthenocarpy in agriculture
- Parthenocarpy helps in the generation of seedless fruits, which are commercially viable due to ease of consumption.
- Seedless fruits such as bananas, seedless grapes, and watermelons have more market demand which increases agricultural profit.
- Plants with parthenocarpy can produce fruits even in the absence of pollinators or unfavorable environmental conditions.
- It is very effective in regions with dwindling pollinator populations or where climatic conditions are adverse to effective pollination.
- Fruits formed through parthenocarpy are usually uniform in size, shape, and texture, and hence more desirable for commercial sales.
- Parthenocarpy makes it possible for some crops to be grown out of season to ensure a constant supply of fruits.
- Parthenocarpic crops can grow under environmental stresses such as extreme temperatures or humidity, thereby ensuring yield stability.
Common examples of parthenocarpic fruits and vegetables
Bananas (Musa spp.), Pineapple (Ananas comosus), Fig (Ficus carica), Grapes (Vitis vinifera), etc. are some examples of parthenocarpic fruits and tomatoes (Solanum lycopersicum), Cucumber (Cucumis sativus), Eggplant (Solanum melongena) are some examples of parthenocarpic vegetables.
Difference between parthenocarpic and other fruits
The main difference between parthenocarpic fruits and other fruits is the development process and seed content. Other fruits develop after pollination and fertilization, whereas parthenocarpic fruits develop without the fertilization of ovules. The ovary grows into a fruit independently, driven by natural hormonal activity or through artificial methods like hormone treatments or genetic engineering.
Parthenocarpic fruits are seedless or with infertile seeds, in this way, they are of great convenience in consumption and further processing, increasing their market attractiveness. On the other hand, normal fruits bear viable seeds. These seeds contribute to the fruit’s ability to reproduce the species.
Parthenocarpic fruits also vary in their dependence on pollination. Since they do not require pollination or fertilization, they can develop in environments where pollinator populations are scarce or conditions are unfavorable for natural fertilization. This adaptability makes parthenocarpic fruits valuable for agricultural systems facing challenges related to climate change and declining pollinator populations. Most other fruits however depend on successful pollination to grow, and hence their production will be more sensitive to environmental and ecological factors.
Role of plant hormones in parthenocarpy
Parthenocarpic fruits usually depend on the exogenous application of plant growth regulators, such as auxins (2, 4-dichlorophenoxyacetic acid, 2, 4-D), naphthaleneacetic acid (NAA), cytokinins (CKs), gibberellic acids, and brassinosteroids.
Auxins
The primary plant hormone auxin is responsible for inducing parthenocarpy through fruit development without fertilization. Artificially applied auxin in parthenocarpy imitates this process and leads to cell division, tissue expansion, and genes activated in the process of fruit development. Auxin maintains the hormonal balance by interacting with gibberellins and cytokinins to continue growth. It is very effective when pollination fails due to environmental factors or a lack of pollinators.
Synthetic auxins like indole-3-acetic acid (IAA) or naphthaleneacetic acid (NAA) are widely used for seedless fruits, such as tomatoes and cucumbers.
Gibberellic acid (GA)
Gibberellic acid is another plant hormone involved in the induction and regulation of parthenocarpy through the production of fruits without fertilization. GA serves as an essential stimulant for the growth of the ovary into a fruit since it imitates the natural hormonal changes resulting from pollination and subsequent fertilization.
Gibberellic acid works in coordination with auxins and other plant hormones, making sure the proper ratio of hormones, which would trigger continuous fruiting. GA is widely applied in agriculture for flowers to induce parthenocarpy. Such crops include grapes, tomatoes, and cucumbers. For example, the spraying of gibberellic acid on seedless grape varieties will ensure larger and uniform berries. GA is also used in the production of seedless tomatoes in greenhouses.
Cytokinin
Cytokinin regulates cell proliferation and is essential in the induction of parthenocarpy in different crops. Cytokinins also favor nutrient mobilization and vascular development that ensure the required resources for developing fruits. In parthenocarpic fruits, cytokinin along with auxin and gibberilin helps in maintaining fruit development by constantly activating cell division and providing metabolic support.
Brassinosteroids (BRs)
BRs are a group of steroid hormones that play an essential role in the growth and development of plants. Compared with auxin, Gibberilins, and Cytokinin; very few BR-induced parthenocarpic fruits have been reported.
Ethylene
Ethylene is the gaseous plant hormone crucial for regulation during parthenocarpy due to its action on fruit setting and the development of some crops. Though ethylene is primarily considered a ripening hormone for fruit, it has the ability to induce and contribute to parthenocarpic processes, particularly in specific fruits such as bananas and tomatoes.
It works by promoting cell expansion in order to develop into a fruit but without fertilization. Ethylene also modifies hormonal balance in an ovary due to its promotion of fruit formation. In interactions involving other hormones including auxins, it amplifies their effects; hence, increases the chances for fruit set through favorable environmental situations.
Impact of parthenocarpy on fruit quality and yield
Impact on Fruit Quality
Seedless Nature: Fruits produced due to parthenocarpy are mostly seedless. It makes them more convenient for consumers. It is highly valued in fruits like bananas, grapes, and watermelons as seeds are unwanted during eating. Parthenocarpic fruits tend to be more uniform in size, shape, and texture, which increases their commercial attractiveness. Uniformity also makes them easier to process and package for industrial use.
Better Taste and Texture: Seedless fruits tend to have a smoother texture and sometimes a sweeter taste because seed development can draw nutrients away during growth.
Increased Shelf Life: In some instances, parthenocarpic fruits have better post-harvest quality, for example, resistance to early spoilage that has made them ideal for transport and storage.
Impact on Yield
Consistent Production: Parthenocarpy ensures fruit development when pollination is poor due to adverse weather conditions such as low temperatures or declines in pollinator populations. This reliability boosts overall yield.
Increased Productivity: Crops farmed for parthenocarpy can often yield more in terms of yields per plant due to the removal of dependence upon successful fertilization and seed setting.
Year-Round Availability: Employment of parthenocarpy in greenhouses and similar controlled environments for fruit production enables the availability of some fruits throughout the year thus increasing productivity, and market availability.
Resistance against Climate Challenges: The removal of dependence on the process of pollination allows parthenocarpic crops to avoid the negative influence of climate changes or inconsistent climate conditions.
How Do Farmers Make Seedless Fruit? (Video)
Future Perspective
Parthenocarpy ensures stable yields even under adverse environmental conditions such as extreme temperatures or reduced pollination brought about by declining insect populations. It would thus enhance food security by offering reliable fruit production across various regions.
Advances in biotechnology and genetic engineering are likely to increase the scope of crops that may benefit from parthenocarpy.
Scientists are working on developing techniques to introduce or enhance parthenocarpic traits in economically important crops like cereals and legumes for seedless or improved fruiting varieties.
Parthenocarpy aligns well with precision agriculture techniques and greenhouse farming, where the controlled application of hormones like auxins, gibberellins, or cytokinins can produce high-quality, seedless fruits. This integration can enhance productivity and reduce dependency on external pollination factors.
Parthenocarpy provides a way to bypass pollinators, providing a solution for the challenges presented by declining populations of bees and insects. It is particularly crucial for crops produced in areas that have limited natural pollinator activity.
Seedless fruits are becoming increasingly in demand as they are easy to use and market. Parthenocarpy provides an opportunity to satisfy consumer preferences while ensuring reliable supply chains for seedless fruit varieties such as grapes, bananas, and watermelons.
As climate change alters crop viability and pollination patterns, parthenocarpy provides resilience through fruit development, regardless of environmental stressors.
Parthenocarpy can decrease resource waste, as it limits the requirement for artificial pollination methods or more water and fertilizer inputs to maximize the success of pollination. It also helps in the efficient use of land to increase yields per unit area.
References
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