Abstract: Cenchrus spinifex is one of the major invasive plants in China, in which seed heterosis is an important trait for its rapid expansion in the habitat. In this paper, we investigated the role of seed heterosis of Cenchrus spinifex in the ecological adaptation based on the morphological characteristics of Cenchrus spinifex heterotypic seeds （M-type and P-type） and the process of their germination in response to temperature changes. The results showed that the thousand-seed weight, length, width, curve circumference and curve width of M-type seeds were significantly greater than those of P-type seeds （P<0.05）, and the germination rate, germination potential and germination index were also significantly higher than those of P-type seeds （P<0.05）. The soluble sugar content of seed germination was significantly affected by the germination temperature （P<0.05）, and the overall soluble sugar content showed a trend of decreasing and then increasing with the increase of temperature, and the soluble sugar content of both types of seeds was the highest at 35℃. The soluble sugar content of P-type seeds was significantly higher than that of P-type seeds （P<0.05）. Except for 30℃, the malondialdehyde content of P-type seeds was higher than that of M-type seeds （P<0.05）, indicating that P-type seeds were more susceptible to stress, and their growth and development performance was inferior to that of M-type seeds. The suitable temperature for the germination of Cenchrus spinifex seeds was 20-30℃, in which the optimum germination temperature of M-type seeds was 20-25℃ and that of P-type seeds was 25-30℃. Therefore, M-type seeds were the main adaptation strategy for Cenchrus spinifex populations when the environment was suitable, and the ability of P-type seeds to germinate in dry and hot environments enhanced the ecological adaptability of Cenchrus spinifex to adverse environments.

Key words: Cenchrus spinifex, Seed heterogeneity, Temperature, Germination

摘要： 少花蒺藜草（Cenchrus spinifex）是我国主要入侵植物之一,其中种子异型性是少花蒺藜草在生境中迅速扩展的重要性状。本文基于少花蒺藜草异型种子（M型和P型）的形态特征及其萌发对温度变化的响应过程,研究异型种子在少花蒺藜草生态适应性中的作用。结果表明少花蒺藜草M型种子的千粒重、长度、宽度、曲线周长和曲线宽度都显著大于P型种子（P<0.05）,且萌发率、发芽势及发芽指数等也显著高于P型种子（P<0.05）。种子萌发时的可溶性糖含量显著受萌发温度的影响（P<0.05）,随着温度升高,可溶性糖总体含量呈现先降低后升高的趋势,两类种子均在35℃时可溶性糖含量最高。除30℃外,P型种子的丙二醛（Malondialdehyde,MDA）含量高于M型种子（P<0.05）,表明P型种子更易受到胁迫,生长发育表现劣于M型种子。少花蒺藜草种子萌发的适宜温度为20~30℃,其中M型种子的最适萌发温度为20~25℃,P型种子的最适萌发温度是25~30℃。因此,M型种子是环境适宜时少花蒺藜草种群主要适应策略,P型种子在干热环境下的萌发能力增强了少花蒺藜草对不良环境的生态适应性。

关键词: 少花蒺藜草, 种子异型性, 温度, 萌发