Question

Which effect of auxin is applied worldwide for plant propagation? (a) Apical dominance (b) Herbicidal action (c) Initiate rooting in stem cutting (d) None of these

Short answer

The effect of auxin that is applied worldwide for plant propagation is (c) Initiate rooting in stem cutting.

Step-by-step solution

Understanding the Effects of Auxin

Auxin is a hormone in plants that has various effects such as promoting cell elongation, regulating phototropism and gravitropism, and triggering apical dominance. It is also known to initiate rooting in stem cuttings, making it useful in plant propagation.

Analyzing the Options

Looking at the options, (a) Apical dominance is more related to the growth architecture of the plant rather than propagation. (b) Herbicidal action doesn't contribute to plant propagation. Instead, it's used to control or eradicate undesirable vegetation.

Identifying the Correct Option

Having analyzed all options, (c) Initiating rooting in stem cuttings, stands out because this effect of auxin helps in the process of plant propagation allowing new plants to be created from the cuttings of a parent plant which is a method used worldwide.

Key concepts

Plant Hormones

Plant hormones are crucial in regulating various growth and developmental processes in plants. Among these hormones is auxin, recognized for its role in promoting cell elongation, influencing the direction of plant growth, and facilitating the development of new roots.

Auxin specifically influences the growth of plants by upregulating cellular activities where growth is needed and reducing them where it's not. In the context of plant propagation, auxin can be applied to stem cuttings to stimulate root growth—enabling a cutting to establish itself as a new plant. Additionally, in the natural environment, auxins are produced at the tips of plant shoots, influencing the way a plant grows in relation to light (phototropism) and gravity (gravitropism).

The understanding of auxin has led to various practical applications in agriculture and horticulture, particularly in the propagation of plants through techniques like stem cuttings, ensuring the consistent and reliable development of healthy new plants.

Applied Benefits of Auxins

Gardeners and commercial growers utilize synthetic auxin formulations to improve rooting success rates when propagating plants from cuttings. This illustrative example of applied plant science highlights the importance of plant hormones in both natural and assisted plant development.

Stem Cutting Propagation

Stem cutting propagation is a common and cost-effective method for plant multiplication. The technique involves cutting a healthy portion of a stem from a parent plant and encouraging it to form new roots. This method is preferred for its simplicity and the fidelity with which the new plant retains the characteristics of the parent.

Auxins play a significant role in facilitating the rooting process. When applied to the cut end of a stem, auxins lead to an increase in the cellular activities that promote root initiation and development. This not only increases the chances of successful propagation but can also significantly reduce the time required for roots to form.

Advantages of Stem Cutting Propagation

• Economic Efficiency: It doesn't require expensive equipment or advanced skills.
• Genetic Consistency: New plants are genetically identical to the parent, preserving desired traits.
• Speed: It allows for faster multiplication compared to seed propagation.

Enthusiasts and professionals alike use stem cutting propagation, combined with the application of auxins, to effectively produce numerous healthy plants within a shorter timeframe.

Apical Dominance

Apical dominance refers to the phenomenon wherein the main central stem of the plant grows more strongly than other side stems or branches. This is primarily regulated by auxin, which is produced in the apical meristem (the growing tip of a plant). Higher concentrations of auxin inhibit the growth of lateral buds, ensuring that the plant grows upwards rather than outwards.

This mechanism is key to plant architecture, as it dictates the overall shape and size of the plant. By understanding and manipulating apical dominance, gardeners can influence how bushy or tall a plant becomes.

Practical Implications

In horticultural practices, the suppression of apical dominance is often desirable to encourage a bushier growth habit. This is achieved by pruning the tip of the plant, which reduces auxin levels and allows the lateral buds to grow. Conversely, maintaining apical dominance is essential for certain crops or when vertical space is limited.

Recognizing the effect of auxin on apical dominance provides insight into how plants allocate resources and grow, highlighting the intricate balance between natural hormone regulation and human intervention for optimal plant growth. Such knowledge is esteemed in agriculture, where crop shape can significantly impact overall yield.