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EFFECT OF SUGAR CONCENTRATION ON POLLINIUM GERMINATION IN SOME MEMBERS OF ASCLEPIADACEAE

TAHIR ALl AND S.I.ALI

Abstract: Effect of sugar concentration on in-vitro pollinium germination in 8 members of Asclepiadaceae viz., Calotropis procera ssp. hamiltonii, Corallima edlllis, Carollima tuIberculata, Ceropegia bulbosa, Glossonema varians, Leptadenia pyrotechnica, Pentatropis nivalis and Perglliaria daemia was studied. Although pollinia of each taxa germinated in a wide range of sucrose concentration (Le. 5-40%) but each taxa showed a specific sucrose concentration at which optimal pollinium germination occurred. In P. nivalis and Per. daemia, coiling and beading of pollen tubes occurred at 20-40% sucrose concentrations while in other taxa at 5-15% concentrations. Optimal sucrose concentration required for in-vitro pollinium germination was similar to the average sugar concentration observed in the floral nectar of the studied taxa except in P. nivalis where maximum pollinium germination occurred at 10% sugar concentration as compared to 24% sugar concentration in its floral nectar.

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