Reproductive efficiency and pollen production in a Nothofagus alpina clonal seed orchard

Abstract

The potential production of pollen per plant is a good indicator of fruit production. In this work the reproductive efficiency index, the average potential pollen production per flower and the functional relationship between the number of anthers and the amount of pollen per flower of Nothofagus alpina were determined. The ratio of viable seeds formed after manual pollination and the seeds formed by natural pollination was calculated. The total of pollen grains per flower was estimated by direct counting. The index of reproductive efficiency was estimated at an average of 0.19. It was found that the number of pollen grains per anther varied among individuals and among years. Pollen production per flower was estimated between 85,703 pollen grains per flower in 2011 and 117,975 in 2013. Low seed production after open pollination could be due to pollen limitation, since the formation of viable seeds after hand pollination was significantly higher. The amount of pollen content in the flowers of N. alpina varies in a direct relation with the pollen grains in the anthers, suggesting that the final production of pollen does not depend on the number of anthers per flower.