少花蒺藜草生活史性状和物质分配对生活史异位的可塑响应

Plastic Response of Life History Traits and Material Allocation to Heterotopia of Life History of Cenchrus spinifex Cav.

少花蒺藜草(Cenchrus spinifex Cav.)是我国北方主要入侵植物之一,自然条件下具有出苗不同步的特性,生活史在时间上异位的现象普遍存在,对农牧业生产具有深远影响。为了探究少花蒺藜草营养和繁殖期时间及比例,物质分配和种子功能性状对生活史异位的响应,本研究通过建立野外原位试验地,采用人工播种刺苞的方式获得生活史异位的少花蒺藜草种群,观察并比较分析5个生育期下少花蒺藜草生活史性状和物质分配的差异。结果表明,出苗时间对少花蒺藜草营养期、繁殖期时间和生育期以及营养期和繁殖期时间占比有显著影响(P<0.05),随出苗时间延后,生育期逐渐缩短,繁殖期时间占比增大;生育期缩短显著降低了果穗生物量、刺苞生物量和数量,但对单刺苞质量无显著影响;少花蒺藜草茎叶比、根冠比和繁殖分配比在5个生育期下差异显著,生育期缩短导致少花蒺藜草茎叶比显著减小,繁殖分配和根冠比显著增大。少花蒺藜草通过调整其主要生活史性状和物质分配适应生育期缩短带来的不利影响,其生育期长度,物质分配和种子功能性状均有一定可塑性。生育期缩短导致的积温和降水等环境因子的限制可能是少花蒺藜草生活史性状和物质分配差异的重要因素。

Cenchrus spinifex Cav.is one of the main invasive plants in northern China.C.spinifex Cav.shows asynchronous emergence under natural conditions,and the phenomenon of life history heterotopic is common and has a profound impact on agricultural production and animal husbandry.In this study,a field experiment was established to investigate the response of the nutritional and reproductive period duration and proportion,material allocation,and seed functional traits to the heterotopic life history of C.spinifex Cav.,and the population of C.spinifex Cav.with a heterotopic life history was obtained by artificially sowing spiny burs of C.spinifex Cav.The life history traits and material allocation of C.spinifex Cav.were analyzed and compared under 5 life-history lengths,and the response of the main life history components and material allocation to heterotopic life history was explored.The results showed that germination time had a significant effect on the duration of the nutritional,reproductive,and growth periods,as well as on the proportion of the nutritional and reproductive periods of C.spinifex Cav.With the extension of emergence time,the growth period gradually shortened,and the proportion of reproductive period duration gradually increased.The shortening of the growth period significantly reduced the spike biomass,spiny bur biomass and number of C.spinifex Cav.plants,but had no significant effect on the weight of a single spikelet.There were significant differences in the stem-leaf ratio,reproductive allocation,and root-shoot ratio among the 5 growth periods.The shortened growth period resulted in a significant decrease in the stem-leaf ratio,while reproductive allocation and the root-shoot ratio significantly increased.C.spinifex Cav.adapts to the adverse effects of a shortened growth period by adjusting its main life history traits,material allocation and seed functional traits,which have a certain degree of plasticity.The limitation imposed by environmental factors such as accumulated temperature and precipitation caused by the shortening of the growth period may be an important factor leading to differences in life history traits and material allocation in C.spinifex Cav.