Effects of low quality soil, drought and systemic pesticides on plant flowering traits in Brassica Napus L.

Abstract: One of the most important ecosystem services is animal pollination, which has been found to increase both crop quantity and quality and hence is important for sustainable food production. To provide food to an increasing population, farming systems are intensifying to maintain high crop yields. However, stressors such as climate change and intensified agricultural production schemes may alter plant flowering traits important for pollinator attraction, with the potential consequence of reducing pollination services. In this study, plants of rapeseed (Brassica napus L.) were exposed to drought, low soil quality and the neonicotinoid clothianidin, a systemic pesticide. Responses in plant flowering traits including nectar and pollen production, size and number of flowers, time before flowering and water content in pollen were measured to find individual or combined treatment effects. My results show that low soil quality in combination with drought reduced pollen and flower production, in addition to this, pesticide treatment in combination with low soil quality seem to increase the production of pollen. Flower production were reduced by both low soil quality and drought as individual factors, suggesting that the plant adapt by primarily reducing the number of flowers rather than reducing traits such as nectar and pollen quantity on each flower. The other plant traits investigated did not show a treatment response. Negative effects from reduced resources important for foraging may decrease pollinator attraction, consequently reducing seed yield.