THE CENTRIFUGE METHOD FOR MEASURING NECTAR YIELD.

Relatively little is known of the influence of environmental factors on nectar yield in plants. The problem is of special importance in the case of the forage legumes, where seed set is closely dependent on bee pollination if other factors are not limiting. In at least red clover, satisfactory nectar production is one of the requisites for ensuring sufficient bee visits. Although the importance of such studies has been recognized, research along these lines has been limited by the lack of a suitable method for measuring nectar production. Such a method must combine rapidity with reasonable quantitative accuracy to permit critical study of these and related problems. The purpose of the present paper is to describe briefly a modified centrifuge technique which satisfies acceptably these criteria. The centrifuge method was first used by Gubin (3) and later by Ewert (2) and Stapel and G?tzache (5). None of these investigators critically evaluated the method, and few technical data, such as the centrifugal speed, radial distance, time of centrifuging, and completeness of recovery, are stated in these papers. A further study of the technique was therefore considered advisable. The method has also been simplified to permit direct volumetric determinations of yield, thereby eliminating the use of an analytical balance and considerably increasing the efficiency with which measurements can be made. All evaluations of the technique have been in terms of red clover but the method appears applicable to many other species.