Which practice involves implanting a scion into a growing plant to combine two plant parts?

The practice of implanting a scion into a growing plant to combine two plant parts is known as grafting. Grafting is a horticultural technique that involves joining the tissue of one plant (the scion) with the tissue of another plant (the rootstock) so that they grow together as a single plant. This method is commonly used to propagate certain plant species, ensuring the new plant inherits desirable traits from both parent plants, such as improved disease resistance, better fruit quality, or enhanced vigor.

Grafting is often employed in fruit tree cultivation, ornamental plants, and certain shrubs, allowing for the combination of various varieties or species in a single plant. The success of grafting depends on the compatibility of the two plant parts and the care taken during the process to properly align and secure them.

The other options do not pertain to this specific practice. Girdling involves removing a strip of bark from around the circumference of a tree, which can alter its growth or health but does not involve combining plant parts. Fumigation is a pest control method using gases to eliminate pests in the soil or on plants. Germination refers to the process whereby seeds develop into new plants, which is unrelated to the practice of combining parts of different plants.