高加索三叶草花蜜腺发育解剖及小花糖分变化研究

Anatomical study of nectar gland development and changes in sugar content in Trifolium ambiguum Bieb.

【目的】高加索三叶草是优良的蜜源植物,了解其花蜜腺形态特征、组织结构及其发育规律对认识其小花糖分变化规律和合理利用该植物资源具有重要意义。【方法】取5个发育时期的高加索三叶草小花,石蜡切片观察细胞组织结构,毛细管法和生理试剂盒测定花蜜量和糖分含量。【结果】(1)单个小花的花蜜量为(0.394±0.095)μL,每1 m^(2)草地花蜜量为(4536.93±1319.34)μL。(2)蜜腺位于9枚合生雄蕊的花丝内侧基部,为雄蕊蜜腺。蜜腺组织在整个泌蜜过程中淀粉粒分布有明显的动态变化,属于淀粉型蜜腺。(3)可溶性糖含量在盛花期最高,为7.978 mg/g;可溶性糖各组分中果糖占比最大,超过50%,在小花的整个发育过程中呈逐渐下降趋势;淀粉占全糖含量的81%~82%,其中盛花期最高,为35.173 mg/g。【结论】高加索三叶草花蜜腺属于雄蕊蜜腺,由分泌表皮和泌蜜组织构成。原蜜由花托维管束提供,经泌蜜组织加工成蜜汁,后由表皮的气孔泌出。小花的可溶性糖含量在盛花期最高,其中果糖占比最大。

[Objective]Trifolium ambiguum Bieb.is an excellent nectar source plant,and understanding the morphological characteristics,tissue structure,and development are critical for proper utilization of T.ambiguum resources.[Methods]Nectar glands of T.ambiguum were collected from five developmental periods and cellular structures were observed in paraffin sections,while the nectar volume and sugar content were determined by capillary method and physiological kits.[Results](1)Nectar glands were found in the medial base of the filament of nine connate stamens.Distribution of starch grains in nectar production process changed dynamically,belonging to the starch-type nectar gland.(2)The nectar volume of a single floret was(0.394±0.095)μL,and the nectar volume per square meter of grass was(4536.93±1319.34)μL.(3)Soluble sugar was the highest in full flowering,7.978 mg/g.Fructose accounted for the largest proportion of soluble sugar components,more than 50%,and showed a gradual decreasing trend throughout the development of florets.Starch accounted for 81%-82%of the total sugar content,with the highest in full flower,35.173 mg/g.[Conclusion]The nectar glands of T.ambiguum belong to the androecium nectar glands,consisting of secretory epithelium and nectar-secreting tissues.The raw nectar is supplied by the vascular bundle of the receptacle,processed into nectar by the nectary tissue,and then exits through the stomata of the epidermis.Soluble sugar of the florets is the highest at full flowering,with fructose accounting for the largest proportion.