無花果之授粉行為及結果習性

Pollination and Syconium Set in Fig （Ficus carica L.）

無花果（Ficus carica L.）的花序屬於隱頭花序（syconium），靠無花果蜂（Blastophaga psenes）授粉。花可分為雄花、長花柱雌花及短花柱雌花，雌蕊先熟（protogyny）；其中，短花柱雌花適於無花果蜂產卵而形成蟲癭，長花柱雌花則是主要產生食用果實的雌花。依其花性及授粉需求可將無花果分為：原生型（或稱喀普利型，Caprifig）、普通型（Common fig）、中間型（San Pedro type）及斯密爾拿型（Smyrnatype）四個系統。原生型無花果具有雄花及短花柱雌花，功能上視為雄株，一年可結果三次；其餘三個系統只具有長花柱雌花，可產生種子，稱為雌株，受生產地氣候之影響，一年結果一次至三次。其中，普通型具有完全單為結果習性，中間型的第二期果必須經授粉受精作用才能結實，而斯密爾型則無單為結果習性。普通型及中間型屬於營養性單為結果（vegetative parthenocarpy），而原生型則屬於刺激性單為結果（stimulative parthenocarpy）。發生於雌雄株間的授粉作用稱為Caprification。由於Caprification發生於雄株之夏果與雌株之第二期果間，故不具單為結果能力之雌株通常無法生產第一期果。無花果在具有接受花粉之能力時，能分泌一些揮發性物質以吸引無花果蜂。雄株與雌株所分泌的揮發性混合物的主成分相同，但量與比例之差異極大，是造成無花果蜂辨識隱頭花序性別的主要因子。共生系統得以維持之主因，在於雌雄株之開花期對無花果蜂造成無從選擇的結果。 Fig (Ficus carica L.) forms syconia and fig wasps (Blastophaga psenes) are needed for pollination. Fig is protogyny and there are three types of fig flowers: staminate flower, short-styled female flower and long-styled female flower. Fig wasps can lay eggs in the ovaries of short-styled female flower to form galls. Fig is divided into four groups according to its sex and pollination demand: Caprifig (Ficus carica var. sylvestris Shinn.), Common fig (Ficus carica var. hortensis Shinn.), San Pedro type (Ficus carica var. intermedia Shinn.) and Smyrna type (Ficus carica var. smyrnica Shinn.). Caprifig possesses staminate and short-styled female flowers. It is so-called male fig as it is functionally male. Caprifig produces three crops a year: mamme crop, profichi crop and mammoni crop. The other three types are female fig and only possess long-styled female flowers. Female fig may produce one or three crops annually, decided by climate. Common fig is completely parthenocarpy, however, pollination is necessary for San Pedo type to produce the main crop. Smyrna type is non-parthenocarpy. Vegetative parthenocarpy is characteristic of Common fig and San Pedo type, however, parthenocarpy in Caprifig is stimilative. Pollination carried out between male and female figs is known as caprification. Only the vegetative parthenocarpic varieties produce the breba crop as caprification occurs between the profichi crop and the main crop. Fig secretes volatile compounds when it is receptive in order to attract fig wasps. Although the identity of the volatile compounds is similar for both sexes, the total contents and the proportions of each component are apparently different and that is the major factor for fig wasps to distinguish the sexes of figs. However, fig wasps cannot choose between the two kinds of figs because of the different times of antheses. Therefore the symbiosis system can be maintained.