Sexual System, Pollen Stainability and Chromosome Number of Zehneria capillacea (Shumach) C. Jeffrey

Abstract

Cucurbit germplasm include cucurbit crops and their wild relatives with diverse reproductive systems. Zehneria capillacea is an edible wild cucurbit with scarce information on the sex morph and ploidy level. This research was carried out to ascertain the sexual system, pollen fertility and chromosome number of Z. capillacea growing in different micro-habitats obtained from four locations in Southern Nigeria. The anthers from plants in their natural habitat were excised at anthesis, the pollen grains dislodged and stained with acetocarmine glycerol jelly while the squash method was used for chromosome preparation from root tips. The result obtained revealed that the breeding system is andromonoecy having staminate and hermaphrodite flowers on the same plant which is an uncommon sex type in cucurbits. The micrographs of pollen stainability provide conclusive evidence that Z. capillacea is functionally andromonoecious with the two floral morphs exhibiting equal pollen number and fertility (100%). The pollen grains are aperturate and colporate with three pores and colpi (tricolporate). The study also confirmed that Z. capillacea is a diploid (2n = 2x = 22) with a basic chromosome number of 11 (x = 11). Polyploids were not observed in the natural populations across the study locations.