Neal Paul R, Anderson Gregory J
Department of Ecology and Evolutionary Biology, Torrey Life Sciences Building, 75 North Eagleville Road, U-43, University of Connecticut, Storrs, CT 06269-3043, USA.
Ann Bot. 2004 May;93(5):603-7. doi: 10.1093/aob/mch068. Epub 2004 Mar 22.
Fabrics used in pollination bags may exclude pollen carried by biotic vectors, but have varying degrees of permeability to wind-borne pollen. The permeability of bags to wind-borne pollen may have important consequences in studies of pollination and reproductive biology. The permeability of four fabrics commonly used in the construction of pollination bags was examined.
Deposition of wind-borne pollen on horizontally and vertically oriented microscope slides was assessed on slides enclosed in pollination bags, as well as on control slides.
It was found that the permeability of fabrics to wind-borne pollen, as measured by deposition on both horizontally and vertically oriented slides, decreased with pore size. However, deposition on horizontal slides was always greater than on vertical slides for a given fabric; this could manifest itself as differential success of pollination of flowers in bags-dependent on flower orientation.
Obviously, bags with mesh size smaller than most pollen grains are impermeable to pollen. However, material for such bags is very expensive. In addition, it was also observed that bags with even moderately small pore size, such as pores (approx. 200 microm) in twisted fibre cotton muslin, offered highly significant barriers to passage of wind-borne pollen. Such bags are sufficiently effective in most large-sample-size reproductive biology studies.
授粉袋所用的织物可能会排除生物传粉媒介携带的花粉，但对风媒花粉具有不同程度的渗透性。袋子对风媒花粉的渗透性可能会对授粉和生殖生物学研究产生重要影响。本研究检测了常用于制作授粉袋的四种织物的渗透性。
评估了封闭在授粉袋中的载玻片以及对照载玻片上水平和垂直放置的显微镜载玻片上风媒花粉的沉积情况。
研究发现，通过水平和垂直放置的载玻片上的沉积量来衡量，织物对风媒花粉的渗透性随孔径减小而降低。然而，对于给定的织物，水平载玻片上的沉积量总是大于垂直载玻片上的沉积量；这可能表现为袋中花朵授粉成功率的差异——取决于花朵的朝向。
显然，网眼尺寸小于大多数花粉粒的袋子对花粉是不透性的。然而，这种袋子的材料非常昂贵。此外，还观察到，即使孔径适中较小的袋子，如捻纤维棉布上的孔径（约200微米），也对风媒花粉的通过构成了非常显著的障碍。这种袋子在大多数大样本量的生殖生物学研究中足够有效。
