濒危植物风箱果的结实特性与种子繁殖力研究

Fecundity characteristics and seed propagation capacity of endangered plant Physocarpus amurensis

风箱果的自然更新能力差,处于濒危状态.该文重点研究了果实出种量及不同母树间种子的重量分异、品质特征和吸水过程,并进行了种子萌发实验,目的是为了确定是否由于有性生殖的限制导致其濒危.结果表明,风箱果结实率很低,含1~2粒种子的果实比例最大,占全部果实的64·47%,平均每个果实中有2·98粒种子.不同母树种子重量分异差异极显著;种子千粒重为1·38g,平均含水量为10·33%,生活力达到87·78%;种子吸水过程有3个明显的阶段:0~6h是急剧吸水的阶段,6~10h吸水基本停滞,10~24h种子重量不再增加;种子的萌发实验表明:不同植株间种子的发芽率差异不显著,平均发芽率为21·44%,但播种出苗率仅为5·56%.结实率、出种量和播种出苗率低,是风箱果自然更新不良、种群难以延续和扩展的重要因素.

Physocarpus amurensis is an endangered species with an extremely narrow distribution in Heilongjiang Province, northeastern China. Its propagation capacity is very poor, and seedling recruitment has rarely been observed under the natural conditions. This study focused on the seed output of fruits, the weight differentiation among individual plants, quality traits and water absorption of seeds. The seed germination test was also conducted aiming to determine whether its rarity could be related to factors causing reproductive limitatiom. The results showed that the fruiting rate was very low, the proportion of fruit with 1-2 grains was very high (64.47%) and mean seed number per fruit is 2.98; the thousand-seed-weight was 1.38 g, the water content of air-dried seeds was 10.33%, and the seed vitality reached 87.78%; the seed water absorption showed three clear stages: the rapid absorption stage was during 0-6 hrs period, the stagnant stage was during 6-10 hrs period and the seed weight did not increase during 10-24 hrs period. The germination test showed that there were no significant differences for germination rates among different maternal plants, ie germination rate could reach 21.44%, but emergence rate was only 5.56%. So low fruiting rate, seed output and seedling emergence rate are the important limitating factors for natural reproduction and population enlargement.