5.4.2 Use of Plant Hormones HT

In this lesson, we will explore the effects of plant hormones and how they are used to control plant growth in various contexts.

Auxins

Auxins are a group of plant hormones that regulate plant growth and development. They are responsible for promoting cell elongation, root development, and apical dominance.

Uses of Auxins:

• Weed killers: Synthetic auxins are used as selective herbicides to control the growth of unwanted plants (weeds) by disrupting their growth patterns.
• Rooting powders: Natural or synthetic auxins are used to stimulate root formation in cuttings, aiding in the propagation of plants.
• Growth promotion in tissueA group of similar specialised cells working together to perform a function. culture: Auxins are used to initiate the growth of plant tissues in laboratory conditions, allowing for large-scale production of genetically identical plants.

Ethene

Ethene, also known as ethylene, is a gaseous plant hormone that influences several physiological processes in plants. Its primary role is in the regulation of fruit ripening.

Uses of Ethene:

• Food industry: Ethene is used to control the ripening of fruits during storage and transport. By manipulating ethene levels, the timing of fruit ripening can be adjusted, allowing for better quality and extended shelf life.

Gibberellins

Gibberellins are plant hormones involved in various aspects of plant growth and development. Their functions include promoting stem elongation, breaking seed dormancy, inducing flowering, and increasing fruit size.

Uses of Gibberellins:

• End seed dormancy: Gibberellins can be applied to dormant seeds to initiate germination, overcoming their natural dormancy period.
• Flowering promotion: In some cases, gibberellins can stimulate flowering, enabling plants to bloom outside their typical flowering season.
• Fruit size enhancement: Gibberellins can be used to increase the size of fruits, resulting in larger and more marketable produce.

Impact on Biodiversity

The use of hormones as weed killers, while effective in managing unwanted plants, can have negative impacts on biodiversity. The selective control of certain plant species may disrupt natural ecosystems, affecting the diversity and abundance of plant species, as well as the associated animal and insect populations.

Conclusion

Plant hormones, such as auxins, ethene, and gibberellins, play significant roles in the control and manipulation of plant growth. Their applications in agriculture and horticulture allow for weed control, rooting, tissue culture, fruit ripening regulation, seed germination, flowering induction, and fruit size enhancement. However, it is important to consider the environmental impact and potential effects on biodiversity when using hormones as weed killers.