Morrant D S, Schumann R, Petit S
Sustainable Environments Research Group, School of Natural and Built Environments, University of South Australia, Mawson Lakes, South Australia, Australia.
Ann Bot. 2009 Feb;103(3):533-42. doi: 10.1093/aob/mcn241. Epub 2008 Dec 11.
Although several methods of sampling and storing floral nectar are available, little information exists on sampling and storing nectar from flowers with low nectar volumes. Methods for sampling and storing nectar from the flowers of species with low floral nectar volumes (<1 microL) were investigated using the flowers of Eucalyptus species.
Sampling with microcapillary tubes, blotting up with filter paper, washing and rinsing were compared to determine masses of sugars recovered and differences in sugar ratios. Storage methods included room temperature, refrigeration and freezing treatments; the addition of antimicrobial agents benzyl alcohol or methanol to some of these treatments was also evaluated. Nectar samples were analysed using high-performance liquid chromatography and the masses of sucrose, glucose and fructose in each sample were determined.
Masses of sugars varied significantly among sampling treatments, but the highest yielding methods, rinsing and washing, were not significantly different. A washing time of 1 min was as effective as one of 20 min. Storage trials showed that the sugar concentration measurements of nectar solutions changed rapidly, with the best results achieved for refrigeration with no additive (sucrose and fructose were stable for at least 2 weeks). Sugar ratios, however, remained relatively stable in most treatments and did not change significantly across 4 weeks for the methanol plus refrigerator and freezing treatments, and 2 weeks for the refrigeration treatment with no additive.
Washing is recommended for nectar collection from flowers with low nectar volumes in the field (with the understanding that one wash underestimates the amounts of sugars present in a flower), as is immediate analysis of sugar mass. In view of the great variation in results depending on nectar collection and storage methods, caution should be exercised in their choice, and their accuracy should be evaluated. The use of pulsed amperometric detection, more specific than refractive index detection, may improve the accuracy of nectar sugar analysis.
尽管有几种采集和储存花蜜的方法，但关于从花蜜量少的花朵中采集和储存花蜜的信息却很少。本研究以桉属植物的花朵为材料，对花蜜量少（<1微升）的植物花朵花蜜的采集和储存方法进行了研究。
比较了用微量毛细管取样、用滤纸吸干、洗涤和冲洗等方法，以确定回收的糖质量和糖比例的差异。储存方法包括室温、冷藏和冷冻处理；还评估了在其中一些处理中添加抗菌剂苯甲醇或甲醇的效果。使用高效液相色谱法分析花蜜样品，并测定每个样品中蔗糖、葡萄糖和果糖的质量。
不同取样处理的糖质量差异显著，但产量最高的方法，即冲洗和洗涤，差异不显著。1分钟的洗涤时间与20分钟的洗涤时间效果相同。储存试验表明，花蜜溶液的糖浓度测量值变化很快，不添加任何物质的冷藏效果最佳（蔗糖和果糖至少稳定2周）。然而，在大多数处理中，糖比例保持相对稳定，在甲醇加冷藏和冷冻处理的4周内以及不添加任何物质的冷藏处理的2周内，糖比例没有显著变化。
建议在野外从花蜜量少的花朵中采集花蜜时采用洗涤方法（需注意单次洗涤会低估花朵中存在的糖量），同时建议对糖质量进行即时分析。鉴于根据花蜜采集和储存方法的结果差异很大，在选择时应谨慎，并评估其准确性。使用比折光指数检测更具特异性的脉冲安培检测法，可能会提高花蜜糖分析的准确性。
