Improvement of yam through breeding is difficult because

Improving yam through breeding is difficult because yam is a type of plant that reproduces vegetatively, meaning that it does not have a sexual reproductive system. This means that new plants are produced from the stem, roots or leaves rather than from seeds. As a result, breeding is not as straightforward as it is with plants that produce seeds. Additionally, yam varieties can rapidly multiply, making it difficult to control their growth and ensure that only the desired varieties are being propagated. Furthermore, the genes in yam plants do not segregate in a predictable manner, making it difficult to produce plants with specific traits through breeding.