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HYBRIDIZATION IN SIDA OVATA COMPLEX II. EVIDENCE FROM BREEDING STUDIES

RUBINA DAWAR, TAHIR ALl AND M. QAISER

Abstract: Breeding studies reconfinned the hybridization between Sida avata Forssk., and Sida tiagii Bhandari. All the three taxa i.e., S. avata Forssk., S. tiagii Bhandari and the hybrid are facultative autogamous as indicated by pollen - ovule ratios and breeding experiments. Chrysis sp., (Hymenoptera) seems to be responsible for pollen transfer between S. avata and S. tiagii in natural populations. Certain insect pollinators were specific such as Bembix sp., and Bambus sp., for S. avata, Apis sp., and Vespa sp., for S. tiagii and Ponera sp., for the hybrid. The limited number of hybrids may be due to less frequent visitation of common pollinator (Chrysis sp.) alongwith the incomplete reproductive barder between both the parents. The restricted gene flow is also evident by least fruit and seed set in hand pollinated reciprocal crosses of the putative parents as compared to the self pollination. It seems that back crosses are impeded due to the absence of common pollinators between the parents and hybrid and meiotic irregularities as indicated by the failure of hand pollinated (back crosses) experiments.

Department of Botany, University of Karachi, Karachi - 75270. Pakistan.