(a) List five aims of crop improvement (b) Define the term selection in crop improvement. (c) List three methods of selection. (d) Explain the following genetic terms: (i) homozygotes (ii) back cross (iii) dominance.
Explanation
(a) Aims of crop improvement: To (i) produce crops with some level of uniformity in growth habit (ii) improve aesthetic value of produce (iii) produce crops that are adapted to particular adverse condition (iv) produce higher yielding crops (v) produce crops that are resistant to pests (vi) produce crops that are resistant to diseases (vii) produce crops that meet some specific manufacturers/consumers requirements (viii) produce crop with short gestation or early maturing crops.
(b) Selection in crop improvement: is the process of choosing specific individuals or groups of plants from a mixed population. It is the process of picking out individuals or groups of plants having specific or desirable characteristics.
(c) Methods of selection: (i) mass selection (ii) pure-line selection (iii) pedigree or progeny selection (iv) bulk selection
(d) Explanation of: (i) homozygotes: Individuals in which the gene pairs for a particular trait are identical (ii) backcross: A cross between an offspring and one of the parents (iii) dominance: This is a condition in which a gene manifests itself phonotypical over the other when the genotype is heterozygous