Pushpakumara, DKNG , Boshier, DH , Simons, AJ .
Pollination Vectors of Artocarpus heterophylls Lam. (Moraceae) in Sri Lanka.
The pollination vectors of Artocarpus heterophyllus Lam. (Moreceae) in a naturalized population in the Experimental Station (ES) of University of Peradeniya, Sri Lanka was investigated during the flowering seasons of 1993/94, 1994/95 and 1998/99, as literature revealed contradictory claims to its mode of pollination. Investigations on insect pollinators indicated the floral visitors are not effective pollinators due to their behavior and lack of contacts between male and female flowers during the receptive period. In the ES, although rotting male inflorescences were visited by numerous vinegar flies (Drosophila spp.), small gnats and micropezid flies, these insects were rarely observed on pollen releasing male inflorescences and the receptive female inflorescences. Except for small gnats, no other insects were observed during the nocturnal observations. Results also revealed that the insect visitors carried a small average pollen load, made only a few visits per hour, and had a long average visiting time. During dry periods, pollen is shed rapidly from male inflorescences, and clearly visible clouds of pollen are produced from small physical disturbances to the male inflorescences at the maximum pollen presentation. Pollen trap experiments also showed the possibility of an airborne pollen flow of A. heterophyllus. Airborne pollen was trapped at up to 25 m from an isolated tree. Wind pollination in A. heterophyllus was further supported by observation of adequate number of pollen grains (over 13 pollen grains per stigma) and grains with pollen tubes on stigmas from inflorescences isolated with insect-proof bags. The amount of pollen grains per stigma usually exceeded the number of ovule per flower. Inconspicuous and non attractive flowers, and lack of nectar, odour or any other floral rewards in the female or male flowers/inflorescences further supported wind pollination of A. heterophyllus. The paper also discusses the validity of using seed-set data to assess the pollination success in a species, particularly where each ovule of a multi-ovulated inflorescence has a single stigma.
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1 - University of Peradeniya, Department of Crop Science, Faculty of Agriculture, Peradeniya, Sri Lanka
2 - University of Oxford, Department of Plant Sciences, South Parks Road, Oxford OX1 3RB, UK
3 - World Agroforestry Centre, Nairobi, Kenya
Presentation Type: Oral Paper:Papers for Topics
Location: 551B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 9:00 AM