Clonal Cultivars from Multistage Multitrait Selection

Abstract

The breeding of vegetatively propagated crops has traditionally used artificial hybridization to generate genetic variation in large seedling populations (10,000 to 100,000 in size), where each seedling is a potential new cultivar. Selection then takes place over a number of clonal generations in which the surviving clones are evaluated more extensively as increasing amounts of planting material become available. Choice of parents, number and choice of crosses, size of progenies and selection intensities are discussed before concentrating on the theory and practice of multistage, multi-trait selection within progenies. The breeding of a number of clonally propagated crops is considered in detail: potatoes (Solanum tuberosum), cassava (Manihot esculenta), sweet potatoes (Ipomoea batatas), sugarcane (Saccharum officinarum), olive (Olea europaea), strawberries (Fragaria × ananassa), raspberries (Rubus idaeus), grapes (Vitis vinifera) and apples (Malus × domestica). Also considered is genomic selection in apple breeding and clonal cultivars produced by apomixis in bluegrasses (Poa species).