Fruiting pattern in longan, Dimocarpus longan: from pollination to aril development

18 Pags.- 1 Tabl.- 6 Figs. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1744-7348In most fleshy fruits, the edible part of the fruit is formed either by the pericarp derived from the ovary wall or by an engrossed receptacle. However, in a number of fruit tree species the edible part is the aril, an outgrowth of the ovule that envelops the seed, and there is a paucity of information on fruit development and fruiting pattern in these crops. To fill this gap, in this work, we have characterised the progamic phase, fruit development and fruit/fruitlet drop in longan, Dimocarpus longan. The progamic phase from pollination to fertilisation took just 3 days; the pollen tubes arrived to the base of the style in 1 day, reached the locule 1 day later and penetrated the ovules 3 days after pollination. Only one of the two ovules present in each longan flower fertilised. However, this did not result in rapid fruitlet growth, since a very slow fruit development occurred up to 6 weeks after flowering. Pollination was required for fruiting and unpollinated flowers dropped 9 days after anthesis. Only 7% of the female flowers produced became fruits. There was a first flower/fruitlet drop 2–4 weeks after flowering that appeared to be related to lack of fertilisation followed by a second fruitlet drop 5–6 weeks after flowering, concomitantly with the rapid growth of the embryo and the aril, that appears to be related to competition for nutrients. These results set a frameline to understand fruiting in tree species in which the edible part of the fruit is a fleshy aril.This work was supported by the Spanish Ministerio de Economía y Competitividad–European Regional Development Fund, European Union (AGL2013-43732-R and AGL2012-40239, and Recupera2020) and Gobierno de Aragón A-43. V. T. P. was supported by a PhD scholarship from the Consejo Superior de Investigaciones Científicas (CSIC), Spain, and Vietnam Academy of Science and Technology (VAST).Peer reviewe