Comparison of Two Nectar Field Sampling Methods on Three Plant Species from the Family Ranunculaceae

Research on floral nectar quantity and composition is increasingly frequent, yet existing studies predominantly focus on plant species with larger flowers that yield abundant nectar. Consequently, standard collection techniques like the microcapillary method are often optimized only for these morphologically larger structures. This study evaluated the applicability of the flower-washing method for nectar sampling in smaller, shallow flowers, comparing its efficacy against the well-established microcapillary method. Three native species from the Ranunculaceae family with diverse blooming phenologies and floral structures were selected: Caltha palustris, Anemone nemorosa, and Clematis vitalba. Nectar samples obtained through both sampling methodologies were analyzed using high-performance liquid chromatography (HPLC) to determine individual profiles and concentrations of sugars, phenolic compounds, and amino acids. The microcapillary method demonstrated notable physical limitations, failing to yield any nectar from A. nemorosa, while success rates remained low for the other two species. Conversely, chemical analysis revealed highly significant discrepancies between the two sampling approaches. The flower-washing method proved highly unreliable, as the mandatory excision of floral tissues caused cellular damage, possibly leading to the leakage of intracellular substances and artificial contamination of the collected nectar. These findings indicate that while flower-washing is occasionally utilized for low-volume flowers, it introduces severe methodological artifacts that compromise data accuracy, highlighting the critical need for refined microcapillary approaches in comparative nectar analysis.