Reproductive analysis of functional interference and role of pollinators in sunnhemp: A late-acting self-incompatible crop

Abstract

Abstract Sunnhemp (C. juncea), a commercially important bast fibre crop possesses late-acting self-incompatibility. The flower is complete, zygomorphic, gamosepalous and herkogamus. Crops with hermaphrodite flowers expressing late-acting self-incompatibility like sunnhemp often encounter sexual interference. The impact of sexual interference in sunnhemp can be studied by understanding its reproductive mechanism and pollinator behaviour. Here, we reported the consequence of different possible types of pollination in sunnhemp under natural conditions and the role of pollinator behaviour in sexual interference. Controlled hand-pollination experiments and seed set analysis were done to understand the influence of sexual interference on seed setting. Self-pollination and pistil longevity studies were undertaken to determine the effect of self-pollination on pistil abscission. Through field observations pollinator identity and how they interact with flowers were recorded. Pollination studies highlight the importance of pollen quality over quantity in determining the reproductive success of sunnhemp. The differential pistil longevity between unpollinated and self-pollinated flowers reassured the presence of late-acting self-incompatible in sunnhemp. Xylocopa auripennis, Xylocopa fenestrate and Xylocopa ruficornis were the most effective pollinators. Further, overall pollination scheme was hypothesized for the species by considering floral development and principal pollinators. We conclude that under natural conditions some self-pollination and geitonogamy were unavoidable, which often causes pollen limitation and ovule discounting in sunnhemp.