eChapter Name: Breeding Systems in Flower and Ornamental Crops
9789389992304
eBook Name: FLOWER BREEDING AND GENETICS
by Manjunath S. Patil, Anil R. Karale
Flowers are classified into three groups- self pollinated, often cross pollinated and cross pollinated- based on the extent of cross pollination which ranges from nil to 5 percent in self pollinated, 5-12 percent in often cross-pollinated and more than 12 percent in cross pollinated flowers. The information on extent of cross pollination is important to decide appropriate breeding methods to develop and improve the crop, to maintain genetic purity of seed, and to decide safe isolation distances from varieties, related species and related genera of the crop.
3.1 Autogamous (Self pollinated) flowers
When the egg in a flower gets fertilized by its own pollen, it is, referred to as autogamy. In statistical terms, it is, explained as the probability that egg gets fertilized by its own pollen as one. The coefficient of inbreeding which also measures the probability of selfing is also one in such crops. The genetic structure of autogamous flower is homozygous. The reasons for autogamy in flowers are essentially homomorphism, cleistogamy and chasmogamy. Homomorphism refers to uniformity in placement of essential floral parts, androecium and gynoecium e.g. Aster (double flowered), Balsam, Bells of Ireland, Carnation, Clianthus, Benghal dayflower (Commelina benghalensis), Gypsophila, Lupine, Salvia, Saponaria, Sweet pea and Sweet William. In autogamous ornamental crops, cross pollination in nature is almost negligible. Autogamous pollination may be of three types viz., autogamous selfing: refers to origin of pollen from anthers of the same flower; geitonogamous selfing refers to pollen from different flower on the same shoot or genet, and xenogamy, crossing refers to pollen from different flower on a shoot from another genet.