密花柽柳的两季开花结实及其生态意义

Ecological Significance of Bi-seasonal Flowering and Fruiting of Tamarix arceuthoides

对分布于新疆荒漠地区的密花柽柳开花物候、传粉及结实特性进行了比较研究。结果表明:①密花柽柳一年有2个独立的花期——春花期和夏花期;春花花期短,仅为11 d,为集中开花模式;夏花花期长,为69 d,但每天开花数量比春花期少,为持续开花模式。②春花和夏花都有自交亲和性,套袋实验表明,春花和夏花都能进行风媒传粉和虫媒传粉。③夏花期访花昆虫种类比春花期多,主要为小茧蜂和甲虫类昆虫,而春花期的主要访花昆虫为蜜蜂和食蚜蝇。④自然状况下春花期的结实率高于夏花期,春花期和夏花期果实的成熟期短,分别为12 d和7 d,能够快速产生种子,形成持续开花和持续散布种子的格局。密花柽柳特殊的两季开花结实特性作为植物对环境的一种适应方式,对于诠释荒漠地区植物特殊的适应机制具有重要价值。

In this paper,the flowering-biological and pollination-ecological properties of Tamarix arceuthoides in a desert in Xinjiang are studied.The results are as follows：（1） T.arceuthoides plants flower twice a year in spring and summer.The spring flowering period is shorter（11 days only） than the summer one,the spring flowering belongs to a mass-flowering pattern,but the summer flowering is an extended-flowering pattern;（2） It is found that T.arceuthoides is self-compatible,but it lacks the self-pollination mechanism,so it needs pollination media.T.arceuthoides plants are pollinated mostly by insects during the spring flowering period but mostly by wind during the summer one;（3） During the summer flowering period,the flowers are visited by both bees（Bracohidae） and beetles,but they are visited almost by bees（Apis indica and Bracohidae） and flies（Syrphidae） during the spring one;（4） Fruiting rate of T.arceuthoides plants during the spring flowering period is much higher than that during the summer one under natural conditions,and T.arceuthoides plants produce seeds quickly in a short fruiting period（12-7days） during both spring and summer flowering periods.T.arceuthoides plants adapt their environment by their unique way,and the bi-seasonal flowering of T.arceuthoides plants is of significance for understanding the adaptation mechanism to habitats.