Abstract
Abstract Niger, Guizotia abyssinica (L.f.), is an important oilseed crop widely grown in Ethiopia and India, but poor pollination is one of the major constraints in achieving the yield potential of the crop. Our aim was to understand better the pollination biology and role of flower insect visitors in reproduction success. Results indicated that full anthesis occured in the morning between 06.00 and 08.00 h and pollen dehiscence eight to eleven hours after anthesis. Stigma receptivity commenced nine hours after anthesis and lasted for the next 24 h. A total of eighteen insect species representing six families visited Niger flowers, and among these, Apis florea and A. cerana were dominant. The flowers were self-incompatible as there was no seed set upon the selfing of floret and selfing of capitulum. The maximum seed set (78.33±0.14%) was noticed when flowers were allowed for open pollination and the lowest was recorded when the whole plant was caged to exclude pollinator visits (0.33±0.67). The time spent by A. cerana and A. florea was 1.35±0.48 and 1.83±0.12 seconds per floret, respectively and 9.63±0.69 and 14.9±0.94 seconds per capitulum, respectively. A. cerana and A. florea were found to be more efficient pollinators of G. abyssinica. Introducing bee colonies might greatly improve the yield, and it is also important to conserve bees in the vicinity of G. abissynica fields during the flowering period. Hence, introducing bee colonies might greatly improve the yield of Niger.
Highlights
Pollination is one of the most fascinating aspects of insect-plant interactions
The capitulum of G. abyssinica has five to six rows of hermaphrodite disc florets surrounded by a row of large female ray florets (Getinet & Sharma, 1996)
The ray florets enhance a plant’s visual display to their mutual partners and a positive association has been observed between pollination success and the possession of rays (Stuessy et al, 1986)
Summary
Pollination is one of the most fascinating aspects of insect-plant interactions. The extent of interdependence is regulated by phenology and floral characters (Ram & Mathur, 1984) and their selection can shape the evolution of floral characters (Andersson, 2008). Pollen dispersal patterns often reflect pollinator foraging behaviour and may not optimize the quality or quantity of mating in plant species (Campbell & Dooley, 1992). The foraging behaviour of the pollinator has implications for a plant’s fitness (Randall et al, 2009). Even in self-compatible species, the tendency of pollinators to visit several flowers of a single plant in a sequence increases the opportunity for self-pollination among flowers and results in increased selfing rate (Harder & Barrett, 1996; Snow et al, 1996; Karron et al, 2009). The foraging behaviour of pollinators plays a vital role in seed set.
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