A preliminary study of nectar production of the field cress,Rorippa indica,in relation to the age of its flowers

Floral nectar production quantity and changes in sugar concentration of the nectar ofRorippa indica were investigated. Flowers were sorted by age. The small flower size was a major factor for the use of BCG test paper in nectar sampling. In flowers of the youngest age category, the nectar volume increased toward the night and decreased during the day. The amount of sugar in the nectar decreased with flower age. The sugar concentration was lower at night than daytime. The variability and changes in nectar concentration enabled various species of insects to forage for nectar.