Nectar production of selected cultivars of Brassica campestris L. And Brassica napus L.

The amount and sugar concentration of nectar produced by two cultivars (Candle, Tobin) of Brassica campestris L. and three cultivars (Altex, Andor, Regent) of Brassica napus L. were determined throughout the day. The effect of temperature and relative humidity on nectar production as well as the preferences for cultivars by honeybees were examined. Cultivars of B. napus produced more nectar than did those of B. campestris. The flowers of both species produced more nectar, with a lower sugar concentration, in the mornings. Correlations were found between the amounts and concentrations of nectar produced and temperature and relative humidity. Flowers sampled repeatedly produced more nectar, with a lower sugar concentration, than did those sampled only once per day. Honeybees did not show obvious preferences for any of the cultivars investigated.