华北平原罗布麻种群生殖分株数量特征及变化规律

通过大样本取样调查，研究了华北平原罗布麻种群生殖分株的数量特征和生殖分配规律．结果表明，在籽粒完熟期，罗布麻种群单个生殖分株重为10．38±7．78g，蒴果生物量和蒴果数分别为1．57±1．59g和7．60±6．56个；种子生物量和种子数分别为0．34±0．33g和582．3±558．7个；生殖分配Ⅰ和生殖分配Ⅱ分别为12．98±7．94和2．75±1．69％．蒴果和种子形成分别需要分株积累1．42和1．77g以上的生物量．蒴果生物量、葫果数、种子生物量、种子数分别与分株总生物量呈极显著的（P〈0．01）线性正相关关系；蒴果数、种子数与茎叶生物量分配呈极显著的（P〈0．01）线性负相关关系；生殖分配Ⅰ、生殖分配Ⅱ和叶生物量分配呈极显著的（P〈0．01）线性负相关关系．单葫果的重量、种子重、种子数、种子毛重、胎座重分别和葫果的长度呈极显著（P〈0．01）的幂函数正相关关系．罗布麻种群生殖分株同时具有同速和异速2种不同增减过程的表型可塑性调节．

Quantitative Characteristics and Regulation Study on Reproductive Ramets of Apocynum Venctum Population in the North China Plain

By large sampling measure on the single dominant species community in the North China Plain, the quantitative characteristics and the reproductive allocation on reproductive ramets of Apocynum venetum were studied in the ripening stage. The result showed that the weight of each reproductive ramet of A. venetum population was 10.38±7.78 g; the biomass and number of capsules were respectively 1.57±1.59 g and 7.60±6.56; the biomass and number of seeds were respectively 0.34±0.33 g and 582.28 ±558.74; reproductive allocationI （RAI） and reproductive allocationII （RAII）were respectively 12.98±7.94 and 2.75±1.69 %. It is necessary to accumulate total biomass of ramet, which was more than 1.42 and 2.1 g for producing capsules and seeds, respectively. The were most significant positive correlations between the biomass and number of capsules and seeds and the total biomass of ramet, respectively （P 〈0.01）, which could be described by linear equation. There were most significant negative correlations between the number of capsules and seeds and the allocation of stem and leaf; there were significant negative correlations between RAI and RAII and the allocation of leaf. There were most significant positive correlations between the weight of capsules and seeds and seed-hair and placenta and number of seeds and the length of capsules in single capsule, respectively （P 〈0.01）, which could be described by power function. There were two different regulations of phenotype plasticity in reproductive ramet of A. venetum at the same time, which were processes of increase/decrease for the isogony and allometry.