Quantitative analysis of avocado outcrossing and yield in California using RAPD markers

The rate of outcrossing in orchards containing 'Hass' avocado (Persea americana Mill.) was determined using RAPD markers. The data represented 2393 fertilization events sampled from two climatic regions of southern California over a period of 3, years. In addition, three potential pollen sources (cultivars 'Bacon', 'Fuerte' and 'Zutano') were investigated using RAPD markers specific to each pollen source. Finally, yield data were collected from sampled trees to investigate the relationship between outcrossing and yield. Log-linear analyses of the resulting data showed that 'Fuerte' was the most effective pollinator of 'Hass' maternal trees independent of climatic region. The analyses also showed that outcrossing rate was strongly dependent on distance from a potential pollen source. There was a weak positive correlation between outcrossing and yield. Most of the variation in yield appeared to be accounted for by other causes. The total data suggested that self-fertilization was responsible for a substantial fraction of fruit set in California groves. (C) 2000 Elsevier Science B.V. All rights reserved.