外来入侵植物簕仔树若干形态和生理生态特性

簕仔树Mimosa bimucronata在广东为外来入侵种,对其种子形态及生理、叶片生理生态特性进行测定,并与原产地（南美洲）和3种本地（中国广东）植物的相关指标对比,以了解其生态适应性。结果表明：种子长4.29mm,宽3.30mm,大小、含水量（6.23%～8.23%）与原产地的无显著差异;可溶性糖、氨基酸和蛋白质含量分别为32.00、8131.06和2487.04μg·g-1（以干质量计）。活种子比例98.89%～100.00%,萌发率仅32.80%;相对电导率5.35%～11.66%。叶片绿色度29.39,但叶绿素b含量高;对比本地植物,在低光照高湿度下,簕仔树净光合速率（以CO2计）1.339μmol·m-2·s-1低,呼吸速率（以CO2计）1.828μmol·m-2·s-1高,在测定时间内未检测出其蒸腾速率;生理生态指标的表现与阳性植物木荷Schima superba类似,而明显与耐荫植物阴香Cinnamomum burmannii幼苗和九节Psychotria rubra不同。利用其阳性植物特征,可进行遮蔽以减轻潜在的生态危害。

Some morphological and eco-physiological characteristics of alien invasive plant Mimosa bimucronata

Mimosa bimucronata is an alien invasive plant in Guangdong, China. Morphological and physiological characteristics of seed, eco-physiological leaf index of the plant were determined. The morphological and physiological parameters of M. bimucronata were compared to native plants growing under field condition （in South America） and three local native species （in Guangdong Province, China）, in order to identify the ecological adaptation of the invasive plant within the region. The results show that seed of M. bimucronata was 4.29 mm in length and 3.30 mm in width with no significant difference in seed size and moisture content （6.23%-8.23%） between the individuals growing in local area and original sites. Soluble sugar, ammonia acid and protein content in the seed are 32.00, 8 131.06, and 2 487.04 μg·g-1 DW, respectively. The percentage of live seed was from 98.89% to 100.00%. The germination rate was only 32.80% with the relative conductivity ranging from 5.35% to 11.66%. Leaf SPAD was 29.39, but had a higher chlorophyll b content as compared to the native species growing under conditions of lower photosynthetic available radiation and higher relative humidity, M. bimucronata had a relative low net photosynthetic rate （calculated by CO2） of 1.339 μmol·m-2·s-1, and a relative high respiration rate （calculated by CO2） of 1.828 μmol·m-2·s-1. Low transpiration rate was measured which was similar to plants of Schima superba grown in the sun but different from the tolerant plants Cinnamomum burmannii and Psychotria rubra. By using difference in the characteristics of plant exposure to sun light and shaded plant, growth characteristics were identified which could be used in minimizing ecological damage of M. bimucronata.