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Reproductive barriers in Annona cherimola (Mill.) outside of its native area

Author:
Mónica González, Julián Cuevas
Source:
Plant systematics and evolution 2011 v.297 no.3-4 pp. 227-235
ISSN:
0378-2697
Subject:
autogamy, Annona cherimola, dichogamy, wind, corolla, cherimoyas, pollinators, farming systems, fruit set, stigma, trees, genotype, gravity, pollen, insects, Andes region, Spain
Abstract:
Cherimoya (Annona cherimola) is a subtropical tree crop of Andean origin whose fruit set results extremely low in farming areas outside of its natural occurrence. The lack of efficient pollinators and dichogamy are often argued to be the main constraints resulting in this low reproductive success. Herein, we describe the reproductive barriers exhibited by this crop and whether wind and insects play a role in cherimoya pollination in Spain, the main region of cultivation. A. cherimola exhibits marked protogynous dichogamy with large differences in the duration of female (around 28 h) and male (<8 h) phases. Stigma receptivity and pollen release do not fully coincide with the morphological changes of the petals defining the female and male phases. Synchronization of sexual phases among different flowers from different trees of the same genotype was high during the whole blooming season. Effective herkogamy of approach type also limits pollen deposition within the same flower. Wind does not play any role in cherimoya pollination. Insect visitors to cherimoya flowers in Spain were found to be inefficient in transferring pollen grains. Cherimoya flowers do not reject self-pollen to achieve fertilization. A. cherimola shows preferential allogamy based on efficient dichogamy reinforced by elevated synchrony among flowers in their sexual phases. Herkogamy hampers autogamy, although pollen deposition by gravity in cherimoya pendulous flowers explains the reduced reproductive success observed in isolated flowers.
Agid:
586737