The ethylene formula is written as :

C₂H₄

      or

 H₂C=CH₂

Ethylene is a plant hormone that significantly influences various aspects of plant growth and development. As a gaseous compound (C₂H₄), ethylene is unique compared to other plant hormones that exist in liquid or solid forms. This gaseous nature allows ethylene to diffuse freely through plant tissues and the surrounding environment, making it a potent regulator of plant processes (Bleecker & Kende, 2000).

It is produced in virtually all plant tissues, particularly in response to stress factors such as mechanical damage, drought, or flooding, as well as during developmental stages like fruit ripening and leaf senescence (Abeles et al., 1992).

One of the most significant roles of ethylene is in fruit ripening. Ethylene accelerates ripening in climacteric fruits, such as tomatoes, bananas, and apples, by triggering biochemical and physiological changes. These include softening, color change, and the conversion of starches and acids into sugars, making the fruit sweeter and more palatable (Barry & Giovannoni, 2007).

Lelievre et al. (1997) found that this ripening process is vital for commercial fruit production, as ethylene is used to control the timing of ripening in agricultural practices, ensuring that fruits mature at the same time for efficient harvesting.

In addition to fruit ripening, ethylene also regulates leaf senescence and abscission, a process critical for plant survival. According to Goren and Karni (1985), ethylene promotes the aging (senescence) of leaves and triggers the shedding (abscission) of leaves, which helps the plant conserve energy and resources under stressful conditions. This process is particularly important under nutrient stress or seasonal changes, allowing plants to direct resources towards new growth or reproductive efforts. Ethylene also influences other growth processes like stem elongation, flower development, and root growth (Ecker, 2006).

Furthermore, ethylene is involved in a plant’s response to stress. It helps coordinate the plant’s reaction to mechanical damage or pathogen attack by activating stress-related genes and triggering defense mechanisms. This ability to respond to environmental challenges enhances the plant’s resilience under stress (Yang & Hoffman, 1984).

In agricultural practices, ethylene is widely used to regulate fruit ripening and promote uniform flowering. Saltveit (2002) discusses how ethylene-releasing compounds, such as ethephon, are applied to crops to accelerate ripening, ensuring that fruits mature uniformly and can be harvested efficiently. This ability to manipulate plant growth processes has made ethylene a valuable tool in improving crop yield and quality.

Abeles, F. B., Morgan, P. W., & Saltveit, M. E. (1992). Ethylene in Plant Biology. Academic Press.

Barry, C. S., & Giovannoni, J. J. (2007). Ethylene and fruit ripening. Journal of Plant Growth Regulation, 26(1), 143-159.

Ecker, J. R. (2006). Ethylene signaling in plants. Current Opinion in Plant Biology, 9(5), 610-617.

Goren, R., & Karni, L. (1985). Ethylene and abscission. Horticultural Reviews, 7, 83-109.

Klee, H. J., & Tieman, D. M. (2013). The tomato ethylene receptor. The Plant Journal, 62(5), 782-789.

Lelievre, J. M., et al. (1997). Ethylene and fruit ripening. Physiologia Plantarum, 101(4), 727-734.

Saltveit, M. E. (2002). Postharvest handling of fruits and vegetables. CRC Press.

Yang, S. F., & Hoffman, N. E. (1984). Ethylene biosynthesis and its regulation in higher plants. Annual Review of Plant Physiology, 35, 155-189.

Determine Optimal Ethylene Concentrations: Identify the concentration range of ethylene that promotes optimal growth and development in various plant species (Schaller, 2012).

Analyze Growth Patterns: Investigate how different ethylene concentrations affect key growth parameters such as stem elongation, root development, leaf expansion, and overall biomass production (Iqbal et al., 2017).

Assess Developmental Stages: Examine the influence of ethylene on specific developmental stages, including seed germination, flowering, fruit ripening, and senescence (Schaller, 2012).

Evaluate Stress Responses: Explore how ethylene concentrations impact plant responses to abiotic stresses (e.g., drought, salinity) and biotic stresses (e.g., pathogens, pests) (Iqbal et al., 2017).

Investigate Molecular Mechanisms: Study the molecular and biochemical pathways through which ethylene mediates its effects on plant physiology and development (Iqbal et al., 2017).

Compare Plant Species: Compare the effects of ethylene on different plant species to identify species-specific responses and potential applications in agriculture and horticulture (Schaller, 2012).

Develop Practical Applications: Develop practical recommendations for the use of ethylene treatments in agriculture to enhance crop yield, improve fruit ripening, and manage plant growth (Khan et al., 2024).

Iqbal, N., Khan, N. A., Ferrante, A., Trivellini, A., Francini, A., & Khan, M. I. R. (2017). Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones. Frontiers in Plant Science, 8, 475. https://doi.org/10.3389/fpls.2017.00475

Schaller, G. E. (2012). Ethylene and the regulation of plant development. BMC Biology, 10(9). https://doi.org/10.1186/1741-7007-10-9

Khan, S., Alvi, A. F., & Khan, N. A. (2024). Role of Ethylene in the Regulation of Plant Developmental Processes. Stresses, 4(1), 28-53. https://doi.org/10.3390/stresses4010003

The figure above shows the regulation of ripening in tomato which is the pathways of the process of the ethylene in plant development to make sure the colour, flavour, texture, aroma and vitamins of the plants.

In a study done by Tucker.G et al. (2017), texture of the fruits will change and will shows the major of features characteristics of fruits ripening. Although the underlying mechanisms are complex and the details between fruits are different, the textural changed is to recognized both softening and changes in cripness and juiciness of the fruit.

In addition, the action of the hormones, which is ethylene is essential and it will signalling the pathways towards the braches to control the ripening of the fruits saparetely.

Tucker.G., et al. (2017). Ethylene and fruit softening. Fruit Quality and Safety, Volume 1.
https://doi.org/10.1093/fqsafe/fyx024

One essential plant hormone that affects many facets of plant growth and development is ethylene. It is essential for climacteric fruit ripening, including apples, tomatoes, and bananas. Fruits become more appealing and marketable when this hormone activates the genes that cause softening, colour changes, and flavour enhancement.

Ethylene is frequently employed in commercial agriculture to guarantee consistent ripening, enhancing the quality and appearance of fruits that are harvested.

Additionally, ethylene makes plants more resilient to environmental stressors. Ethylene controls stress-responsive genes that aid plants in adjusting to harsh environments, such as drought, salinity, or flooding.

Besides, it coordinates responses that defend against biotic stressors and is a key component of plant defence mechanisms against pathogens. Ethylene is a crucial part of plant resilience because of these properties.

Ethylene also has a beneficial effect on seed germination. In some plant species, it aids in breaking seed dormancy and frequently works in tandem with gibberellins. Ethylene facilitates faster and more consistent plant establishment by encouraging germination, which is essential in both agricultural and natural environments.

Ethylene is also useful for synchronising flowering cycles in horticulture operations since it promotes flowering in certain plants, such as pineapple and certain bromeliads.

Ethylene aids in the structural development of roots by encouraging the growth of adventitious roots and root hairs, especially in wet environments. This enhances the plant's capacity to effectively absorb nutrients and water.

Moreover, ethylene promotes cell elongation and expansion, which helps submerged plants like rice endure and flourish in low-oxygen conditions.

Lastly, ethylene promotes the process of leaf abscission, which might be useful in regulated farming operations. Plants can boost overall growth and reroute their resources to healthier tissues by eliminating old or broken leaves.

Ethylene is used to defoliate leaves in crops like cotton before to harvest, making collection simpler and producing higher-quality harvests.

This table assumes that moderate concentrations of ethylene enhance germination, while higher concentrations (like 300 ppm) might begin to inhibit growth due to stress responses

Abu-Goukh, A. B. (2013). 1-Methylcyclopropene (1-MCP) a breakthrough to delay ripening and extend shelf-life of horticultural crops. Univ. Khartoum J. Agric. Sci, 21, 170-196.

Li, X., Wang, X., Zhang, Y., Zhang, A., & You, C. X. (2022). Regulation of fleshy fruit ripening: from transcription factors to epigenetic modifications. Horticulture Research, 9, uhac013.

Saltveit, M. E. (1999). Effect of ethylene on quality of fresh fruits and vegetables. Postharvest biology and technology, 15(3), 279-292.

Vishal, B., & Kumar, P. P. (2018). Regulation of seed germination and abiotic stresses by gibberellins and abscisic acid. Frontiers in plant science, 9, 838.

Fruits like tomatoes undergo a complicated process of ripening that is controlled by a number of pathways, including perception and ethylene synthesis. By modifying transcription factor genes that regulate fruit characteristics like colour, flavour, texture, aroma, and vitamin content, ethylene plays a crucial part in this process (Li et al., 2022). The pathway depicted in the diagram highlights how climacteric ethylene synthesis is activated by fruit developmental programs that resulting in ethylene perception and signal transduction.

The table's presentation of the effects of ethylene on seed germination shows that the percentage of germination after two days is highly influenced by ethylene concentration. The initial germination rate for the control group (0 ppm) was 50%. The germination rate increased to 65% when the ethylene concentration was raised to 100 ppm, and to 80% when it was raised to 200 ppm. The germination rate dropped to 70% at 300 ppm, which suggesting that increased ethylene concentrations may cause stress reactions that prevent germination.

In summary, ethylene is essential for plant growth and development, and the effects it has vary based on the plant species and concentration. Low to moderate levels of ethylene support important developmental phases like flowering and fruit ripening, encourage healthy growth, and improve seed germination. On the other hand, too much ethylene can impede growth, leading to early senescence, stunted roots, and decreased leaf expansion.

Although too much ethylene can exacerbate the effects of stress, it also aids plants in responding to environmental stresses like drought and salinity. By comprehending these concentration-dependent reactions, ethylene in agriculture can be better managed to maximize crop growth and yield while reducing adverse effects.

Ethylene is a key part of the plant's environment that plays an important role in plant growth, including seed germination and seedling development. The balance between two hormones, gibberellins (GAs) and abscisic acid (ABA), controls whether a seed stays dormant which is unable to germinate even in good conditions. For many plants, ethylene is needed to break dormancy. Ethylene works best at concentrations between 0.1 and 200 μL L-1 to help dormant seeds start germinating (Vishal & Kumar, 2018)

The results show how important it is to control ethylene levels in farming. Adjusting the amount of ethylene can help seeds germinate better and improve fruit ripening, leading to higher quality and better harvests. Future studies could look into how high levels of ethylene cause stress in plants and find ways to reduce these negative effects (Iqbal et al., 2017)

For future studies we can use Ethylene Inhibitors which is to test chemicals or natural compounds to minimize the harmful effects of excessive ethylene since chemicals like 1-Methylcyclopropene (1-MCP), which stop the ethylene from triggering ripening or stress (Abu-Goukh, 2013).

Secondly, environmental Modifications because Changing the environment can also help to control the ethylene levels since Lowering the temperature is an effective way to slow ethylene production and ripening. Controlling humidity is also important to prevent mold build up that can cause disease.

These two methods can help to keep the crops fresh after harvest and ensure good quality of food when reaching the consumers.