胡卢巴属4种短命植物个体大小依赖的繁殖输出与生活史对策

SIZE-DEPENDENT REPRODUCTIVE OUTPUT AND LIFE-HISTORY STRATEGIES IN FOUR EPHEMERAL SPECIES OF TRIGONELLA

对准噶尔荒漠中胡卢巴属(Trigonella)4种短命植物网脉胡卢巴(T.cancellata)、单花胡卢巴(T.monan-tha)、直果胡卢巴(T.orthoceras)和弯果胡卢巴(T.arcuata)的物候特征及生物量分配进行了比较研究,结果表明:1)这4种植物的萌发对策多样,具有春、夏、秋萌现象,但以春、秋季萌发为主。其萌发时间在种间差异不明显,而与温度、降水等环境因子密切相关;2)生长发育快,生活周期短,一次结实,在干热夏季来临前完成生活周期,因此属于典型的避旱型植物;3)秋、春萌株在早春返青或种子萌发后,经过短暂的营养生长后很快进入生殖生长,通过物候期(尤其是营养生长与生殖生长阶段)的迅速转换来获得高的繁殖力,最后达到较高的繁殖产量;4)繁殖分配比率均较高,分别达62.3%、51.9%、54.3%和58.3%,且其繁殖输出与植株大小呈正相关;5)萌发时间不同的植株(春、秋萌株)在大小及繁殖输出上差异显著,但繁殖分配比率差异不显著,说明由萌发时间差异引起的繁殖输出差异归根结底是由植株大小差异引起的。最后探讨了胡卢巴属这4种短命植物的生活史对策以及因萌发时间不同产生的植株在个体大小、生存力和繁殖输出等方面的差异对准噶尔荒漠干旱环境的适应意义。

Phenological characteristics and patterns of biomass allocation were studied in four ephemeral species of Trigonella （T. cancellata, T. arcuata, T. monaraha and T. orthoceras） from the Zhungaer desert. The results showed that germination strategies were diverse among species. Seed germination occurred in the spring, summer and autumn in all four species, but was most prevalent in the spring and autumn. The germination time of seeds was very closely related to environmental factors, such as temperature and precipitation. There were no obvious interspecific differences in germination time. Plant growth was quick and the life cycle short in all four species. The fruits maturate before the arrival of the arid summer season. All four species are monocarpic, and their life-history strategy can be described as that of escaping aridity. The reproductive yield of plants germinated in the spring and autumn was maximized by an instantaneous switch from vegetative growth to reproductive growth after a short period of vegetative growth. The four species allocate a high proportion of carbon to reproductive output and was 62.3%, 51.9%, 54.3% and 58.3% for the four species, and the absolute measures of reproductive output were size-dependent. The reproductive output increased with plant size, with the rvalue 0. 989, 0. 935, 0. 720 and 0. 924 in all the four species （p 〈 0. 001）. There were significant differences in the size （p 〈0.01） and the reproductive output （p 〈0.05, p 〈 0.01 ） among plants that germinated in different seasons. The plants that germinated in the spring were smaller and their reproductive output lower than those hat germinated in the autumn, but the difference in the proportion of reproductive allocation was not significant （p 〉 0.05）. These results indicate that differences in reproductive output can be explained by size differences in plants from different germination times. Finally, we discussed the life-history strategies of the four ephemeral species and analyzed their differences based on individual size, survival ability and reproductive output of plants germinated during different season, and their adaptation strategies to the arid environment of the Zhungaer desert.