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Production of seedless mandarins such as ‘Nules’ clementine mandarin (Citrus clementina Hart. Ex Tan.) and ‘Afourer’ mandarin [C. sinensis (L.) Osbeek x C. reticulata Blanco] is increasing in California as consumers' interest in seedless, easy peeling, and good tasting mandarins increases. The fruit would produce seeds if cross-pollination with compatible pollen source occurred. It is almost impossible to prevent cross-pollination between compatible mandarin cultivars by honeybees (Apis mellifera L.) within the multi-faceted agricultural environment in California. To produce seedless mandarin, growers either plant a single cultivar in a large solid block or try to use pollen-sterile navel oranges (C. sinensis) or satsuma mandarins (C. unshiu Marco.) as buffers to prevent cross-pollination. The question of how many rows of buffer trees or spacing can effectively prevent cross-pollination by honeybees between compatible mandarins is unclear. We initiated a study using fluorescent-labeled AFLP markers to determine the pollen parentages of ‘Nules’ clementine seedlings and ‘Afourer’ mandarin seedlings from two orchards in California. The longest distance of pollen flow at an orchard near Madera was 521 m. The pollen of ‘Minneala’ tangelo (C. reticulata x C. paradisi Macf.) was able to disperse across a minimum of 92 rows of ‘Lane Late’ navel oranges plus two rows of ‘Afourer’ mandarins to pollinate ‘Afourer’ mandarins. We also found that all the seedlings of ‘Nules’ clementine mandarin at an orchard near Bakersfield had been poninated by ‘Afourer’ mandarin pollen. The pollen of ‘Afourer’ mandarin was able to disperse up to distances between 837 and 960 m to pollinate ‘Nules’ clementine. The pollen dispersal distance found in this study was at least 16 times longer than previously reported in a citrus orchard. Growers need to consider a much larger space or buffer rows to prevent cross-pollination and produce seedless mandarins in California. [ABSTRACT FROM AUTHOR]

The Chilean genus Leucocoryne has exceptional qualities as an ornamental plant that is being developed through breeding. Little is known about the origin of its genetic variation for flower phenotype. Our hypothesis is that, despite having a perfect flower, Leucocoryne has an outbreeding behavior due to self-incompatibility. Greenhouse studies were conducted to study self-incompatibility. In 2000, one species L. purpurea Gay, and two distinct populations Leucocoryne sp. Pichicuy and Leucocoryne sp. Chigualoco were used, whereas in 2001, L. coquimbensis F. Phil. and Leucocoryne sp. Alcones and Leucocoryne sp. Talinay were added. Field studies were carried out in 2001 at La Campana (lat. 29°S, Valparaíso Region, Chile) and Bosque de Fray Jorge (lat. 33°S, Coquimbo Region, Chile) National Parks with L. ixioides Lindley and L. purpurea, respectively. The index of self-genetic incompatibility (ISI) was measured as the average number of seeds per fruit produced by self-pollination divided by the average number of seeds per fruit produced from cross-pollination. The average ISI values for 2000 and 2001 were 0.08 and 0.06, respectively, meaning that Leucocoryne is largely self-incompatible. In the field seed set was compared between flowers that were isolated from insects and those that were not. None of the isolated flowers produced seeds, instead nonisolated flowers produced an average of 29 seeds per fruit at La Campana and 56 at Bosque de Fray Jorge. Leucocoryne's self-incompatibility and outcrossing behavior plus its capacity to fix any genotype via asexual reproduction, most likely contribute to its large variation for flower color, shape, size, design, and aroma. Due to Leucocoryne's reproductive behavior it would be difficult to breed for homozygous inbreds and pure hybrid cultivars [ABSTRACT FROM AUTHOR]