Reproductive biology of Physalis angulata L. (Solanaceae)

Abstract

Physalis angulata L., a member of the family Solanaceae, known popularly in Brazil as “camapu”, is widely used in folk medicine. Its leaves have various pharmacological activities and fruits can also be used as human food. Considering the species’ potential economic importance, further knowledge is necessary of its reproductive biology for germplasm conservation and to obtain new hybrid combinations in breeding programs. Therefore, the objective of this study was to elucidate aspects of the reproductive biology of P. angulata. We investigated the floral morphology, anthesis, nectaries and pollinator-attraction structures, identified floral visitors, and estimated pollen viability by the colorimetric method with acetocarmine and 2,3,5-triphenyltetrazolium chloride (TTC) at different collection times. In addition, we evaluated the reproductive systems by measuring the pollen/ovule ratio (P/O), as well as by observing pollen-pistil interaction and seed germination after pollination. The P. angulata plants presented hermaphrodite flowers, and the floral opening occurred between 06:00 h and 08:00 h. Anthers and pollen were the main attractive structures to pollinating insects, especially Apis mellifera, the floral visitor found in greatest abundance, followed by nectar, which was analyzed by neutral red solution. Regarding pollen viability, in the first three collection hours it was greater than 90 % according to both staining methods evaluated, and no in vitro pollen germination was observed. According to the P/O ratio, P. angulata was classified as facultative autogamous. Controlled pollination under field conditions indicated the species is self-compatible with a mixed reproductive system. With respect to fruit production and seed formation, the plants originating from natural self-pollination had the best results, with a fruiting rate of 86 % and production of 156 seeds per fruit. The results obtained from studies of the reproductive biology can aid in planning of crosses and establishment of Physalis breeding programs, and also increase the efficiency of controlled pollinations for agronomic purposes.