Pantnagar Journal of Research

Abstract

Oilseed Brassica is an important source of oil for people worldwide. Oilseed Brassica crops largely attract hymenopterans because Brassica flowers are well adapted to generalist insect pollinators; they produce large amounts of pollen and nectar throughout the entire flowering period, which draws the attention of most of the insects. In the current study, we studied flower morphological characters of different oilseed Brassica species in relation to floral visitors along with their abundance rate at Norman E. Borlaug Crop Research Centre in Govind Ballabh Pant University of Agriculture and Technology, Pantnagar (Uttarakhand) during the rabi season 2020-21. Results revealed that Apis mellifera had the highest relative abundance (42.11%) in oilseed Brassica, whereas, among oilseed Brassica cultivars, B. nigra reported the highest bee abundance (19.05%). However, among bee species and different Brassica cultivars, A. mellifera (5.06 bees/m2 /5min) showed the highest abundance in B. carinata followed by Halictus spp. (3.78 bees /m² /5min) in B. nigra. Large size flower structures were found in B. napus (variety- GSC-6) and B. carinata while small flowers were found in B. nigra, therefore A. mellifera showed positive significant correlation with flower morphological characters viz., petal length (r = 0.791*) and outer stamen (r = 0.732*) and Halictus spp. reported negative significant correlation with flower morphological characters viz. sepal length (r = -0.823*) and inner stamen (r = -0.799*). The results suggested A. mellifera species could be effective pollinators of large flower sized Brassica cultivar, and Halictus spp. could be effective pollinators of small flowers sized Brassica cultivar. This association also occurs between other bee species and Brassica variety, except in case of A. florea. On the other hand, the activity of A. florea in oilseed Brassica is independent of floral morphological characteristics and may be influenced by other factors like as weather conditions, nectar availability of pollen etc.