作 者 ：王英强, 张奠湘, 陈忠毅
期 刊 ：植物生态学报 2005年 29卷 4期 页码：599-609
Keywords:Alpinia oxyphylla, Flowering, Flexistyly, Pollination, Breeding system,
摘 要 ：益智（Alpinia oxyphylla）的花期从2月底至4月下旬；单株花期（花序）约为16～26 d，通常为23～26 d；单花花期一般为1 d。正常情况下，益智和其它山姜属植物一样，具有花柱卷曲性促进异花授粉的机制，表现出两种类型：花柱上举型和花柱下垂型，其花柱卷曲运动的节律与其它已报道的山姜属植物基本一致。但观察发现，当遭遇低温天气时(日最高气温<18℃),单花花期延长为2 d，无论是上举型个体还是下垂型个体，均只表现出一种花型——下垂型：上午开花时花柱弯向上，柱头位于已开裂散发出花粉的花药上方，直到第二天上午6∶30～11∶00间，花柱才陆续地慢慢向下运动，柱头下降至与花药等高或位于花药下方。益智的主要传粉昆虫是蜜蜂（Apidae sp.）、木蜂（Xylocopa sp.），绝大多数的访花者的访花目的是吸蜜。益智的花蜜分泌量（8.37～15.79 μl）和花蜜含糖量（30.12%～32.83%）较高，花蜜是益智作为传粉者访花的最主要的报酬。实验结果还表明，益智花部中唇瓣对昆虫访花有显著的招引作用；益智的花蜜对蜜蜂的访花频率有显著的影响，对木蜂有一定的招引作用，但并不显著。而花粉（花药）则对昆虫的访花频率影响不大。人工授粉实验结果表明益智存在自交亲和性，无论是上举型或下垂型个体自交和异交均有较高的结实率；人工自交和异交的结实率在上举型植株中存在较大的差异，而在下垂型个体中则差异不明显；去雄套袋、去柱头套袋和完全套袋不授粉等处理均不结实，表明益智不存在无融合生殖现象和自动自花授粉现象。益智的繁育系统是异花授粉交配系统。
Abstract:A new behavioral outbreeding mechanism, “flexistyly”, was found in some species of the genus Amomum and Alpinia (Zingiberaceae). In this paper, the floral and pollination biology of Alpinia oxyphylla were studied in two populations at the South China Botanical Garden in Guangzhou during the 2002-2003 flowering seasons. The objectives of this study were to determine whether A. oxyphylla showed the same flexistyly pollination mechanism as that in other species of Alpinia previously reported and to examine the breeding system. According to our observation, flowering of A. oxyphylla took place from late February to late April. The flowering period of inflorescence lasted on average about 16-26 d, with most individuals at 23-26 d, and anthesis of a single flower lasted 1 d. Generally, populations of A. oxyphylla had two floral morphs that differed in flowering behavior: the cataflexistylous morph in which the stigma is held erect above the dehiscent anther when anthesis begins in the morning and becomes curved under the anther in the afternoon, and the anaflexistylous morph in which the receptive stigma is curved under the indehiscent anther in the morning and moves into a reflexed superior position above the anther as it begins to shed pollen in the afternoon. The stylar movements in the two floral morphs were synchronous, and they had similar traits to those found in other Alpinia species previously reported. However, our observations indicated that if the maximal air temperature was under 18 ℃, the anthesis of a single flower was prolonged to 2 d, and the populations of A. oxyphylla showed only a single floral morph, viz., the cataflexistylous morph, in which the stigma was held erect above the dehiscent anther when the flower starts to open in the morning and begins to curve under the anther until the second day at 6∶30-11∶00 a.m. During the flowering period, both the stigma acceptability (H2O2 test) and pollen viability (MTT test) held high levels (>96%) and even retained levels above 75% until 9∶00 a.m. on the second day when the flower withered. The P/O ratios of the two floral morphs were different: the cataflexistylous morph had lower pollen grains and P/O ratio than that of the anaflexistylous morph, but approximately equal ovules. Field experiments indicated that A. oxyphylla was self-compatible. The seed sets were significantly high in both out-crossed and artificial self-pollinated flowers, while no seed set occurred in bagged emasculated flowers and bagged flowers indicating that there is no apomixes. There were significant differences in the seed set between the self-pollination and cross-pollination treatment on anaflexistylous morph. However, no significant differences were found in the seed set between the self-pollination and cross-pollination treatment on the cataflexistylous morph. Our results showed that the breeding system of A. oxyphylla is xenogamy and dependent upon insects for fertilization. The effective pollinators were solitary bees and the honeybee, which visited the flowers mostly for nectar. Uhe pollen is starchy and the flower produced ample nectar, 8.37-15.79 μl, with a sugar concentration of 30.12%-32.83%, which was the main reward for pollinators. During the day, the nectar volume augmented with time and attained a peak (15.79±5.7) μl at about 14∶00 p.m., after which it descended to (11.22±8.11) at about 18∶00 p.m.; however, the nectar sugar and amino acid (0.031±0) mg·ml-1 concentrations were steady. Our observations also showed that the labellum with red stripes, which act as a “honey guide”, may be an indirect advertisement, and nectar may be a direct advertisement in attracting pollinators.