Influence of Pollinators on Polyembryony in Citrus

Heverlee-Louvain

Bandaufführung

168645

Polyembryony constitutes one of the major problems in citrus improvement because it makes difficult the identification of hybrids, particuarly in crosses involving taxonomically closely related parents. Despite recently developed techniques for solving the problem, such as those based on enzymatic and DNA polymorphisms, their regular use as part of an improvement program is very expensive, thus imposing a limiting factor. Basic studies aimed at increasing knowledge on behavior of citrus polyembryony may be useful in minimazing its expression, reducing the number of seedlings to be analysed from polyembryonic seeds. It is well known that the degree of polyembryony of a citrus variety is influenced by the environment, variations being observed from seed to seed, from fruit to fruit, from sector to sector in the same plant and from year to year. This paper concerns an understanding of interactions between polyembryony and environmental factors, and its objective was to determine the influence of pollinators on the number of embryos in citrus seeds. The fruits used in the study were from controlled pollinations involving several cultivars, such as sweet oranges, lemons, mandarins and mandarin hybrids, in the Citrus Breeding Program of the Natioal Center for Research in Cassava and Tropical Fruits-CNPMF, of the Brazilian Agricultural Research Corporation-EMBRAPA. Estimates were made of the average number of embryos per seed, range of number of embryos per seed adn percentage of polyembryony, and these values were compared in the same female parent, crossed with several different male parents.