Study of some factors of conservation of pollens of two plant species (Callistemon rigidus and Hymenocardia acida) of bee flora of Adamawa (Cameroon)

To contribute to the preservation of the bee flora of Adamawa, a study to determine the optimal conditions for preservation of Callistemon rigidus and Hymenocardia acida pollens, two endangered bee species, was conducted from March 2006 to March 2007 in this region. The study began by anthers collection at the experimental site and they were brought to the laboratory where fresh pollens are collected and undergo in vitro germination and storage tests. These tests have required the installation of two solidified media culture: Brewbaker and Kwack (BK) and Heslop-Harrison (HH) media to evaluate pollens germination under the influence of some physiological factors and assess the influence of storage at + 10 and -20 degrees C with and without initial drying. The results show that sucrose concentrations of 10 and 15% on BK medium has produced respectively 60.69 +/- 3.1 and 04.49 +/- 0.21% as the highest values of germination percentage in Callistemon rigidus and Hymenocardia acida. Temperatures of 30 and 25 degrees C which produced 60.69 +/- 2.53 and 04.25 +/- 0.29% of germination and pH 5 with 55.14 +/- 4.14% and 6.8 with 04.54 +/- 0.6% were respectively favourable in the same order for the germination of both species of pollens. Time for a week of drying allowed the extension of storage time of both species of pollens as from +10 to -20 degrees C. The Callistemon rigidus pollens were generally more tolerant to the storage at-20 degrees C showing the critical period of storage exceeding 22 weeks while those of Hymenocardia acida were less tolerant to both temperatures with most critical period of storage established to 8 weeks.