Flowering of siberian peashrub (Caragana arborescens Lam.) and its forage value to pollinating insects

Abstract

Under the conditions of Lublin (central-eastern Poland), observations were conducted on the flowering of Caragana arborescens shrubs for two growth seasons as well as nectar and pollen production by the flowers of this species was investigated. The flowering period of Caragana arborescens began at the turn of April and May and lasted for 24 days, while for a single flower it was 6.30 ± 0.79 days. The average weight of nectar, sugars and pollen produced by 10 Siberian peashrub flowers was, respectively: 46.70 ± 8.39 mg, 22.79 ± 6.10 mg, and 4.45 ± 0.34 mg. The nectar sugar concentration amounted 49.60 ± 10.08%. Pollen grains reached average dimensions of 21.94 ± 0.76 μm x 21.52 ± 0.71 μm. During a growing season, one Caragana arborescens shrub can provide on average 101.8 g of nectar, 49.7 g of sugars, and 9.7 g of pollen.