Langenberger Michael W, Davis Arthur R
Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2.
Am J Bot. 2002 Oct;89(10):1588-98. doi: 10.3732/ajb.89.10.1588.
The dynamics of nectar production were studied in perfect florets of two varieties (Karzo, Moran) of annual caraway (Carum carvi L., Apiaceae). Florets were protandrous and strongly dichogamous, lasting 7-15 d but producing nectar from the stylopodia for 4-12 d, in an interrupted fashion. Nectar secretion began during a floret's phase of stamen elongation and anther dehiscence. After reabsorption of uncollected nectar, at which point nectary surfaces were completely dry, the two styles elongated and a second bout of secretion commenced during the female phase, up to 5 d later, when a floret became receptive to pollination. During the male and female phases, respectively, 0.392 ± 0.064 μL and 1.083 ± 0.261 μL of nectar of similar solute concentration (844 mg/mL) was produced per ten florets. On a daily basis, florets yielded 1.5-fold more nectar in the female than during the male phase. First-time nectar removal throughout the female phase did not match the sum of nectar quantities from male and female phases combined, suggesting that under natural conditions, any uncollected male-phase nectar, once reabsorbed, is not made available to visitors of the same florets when in the female phase. Nectar-sugar composition differed between bouts of secretion; it was hexose-rich (59.6% fructose, 26.9% glucose, 13.6% sucrose) initially, but hexose-dominant (70.2, 26.8, 3.1) during the female phase. A 5.7-fold difference in mean nectar production per floret occurred among plants.
对一年生香菜（Carum carvi L.，伞形科）两个品种（卡尔佐、莫兰）的完全花小花的花蜜分泌动态进行了研究。小花为雄性先熟且严格雌雄异熟，花期持续7 - 15天，但花柱基部分泌花蜜的时间为4 - 12天，呈间断性。花蜜分泌始于小花雄蕊伸长和花药开裂阶段。未收集的花蜜被重新吸收后，蜜腺表面完全干燥，随后两个花柱伸长，在雌性阶段开始第二轮分泌，这一过程在小花开始接受授粉前最多持续至5天后。在雄性和雌性阶段，每十朵小花分别产生溶质浓度相似（844毫克/毫升）的花蜜0.392±0.064微升和1.083±0.261微升。每日小花在雌性阶段产生的花蜜量比雄性阶段多1.5倍。在整个雌性阶段首次去除的花蜜量与雄性和雌性阶段花蜜总量之和不匹配，这表明在自然条件下，任何未收集的雄性阶段花蜜一旦被重新吸收，在小花处于雌性阶段时就不会被同一朵小花的访花者获取。不同分泌轮次的花蜜糖成分有所不同；最初富含己糖（59.6%果糖、26.9%葡萄糖、13.6%蔗糖），但在雌性阶段以己糖为主（70.2、26.8、3.1）。不同植株间每朵小花的平均花蜜分泌量存在5.7倍的差异。
