狼毒种子萌发特性与种群更新机制的研究

研究了采集于植株上的和收集于土壤种子库的狼毒(Stellera chamaejasme)种子在不同温度、光照和5种预处理(即破裂种皮、去除种皮、98％H2SO4浸种5min、0．2％KNO3浸种24h、10℃低温保存1周)条件下的萌发力。结果表明，狼毒种子萌发率较低，25℃恒温、黑暗条件下萌发率为13％，较适宜的萌发温度为30℃恒温或10～30℃变温，破裂种皮和去除种皮萌发率显著提高，25℃恒温、光暗交替条件下萌发率分别为49％和47％，浓硫酸浸种5min处理萌发率可达到32％，KON3浸种和10℃低温保存两个处理对促进狼毒种子萌发效果不明显，狼毒种子萌发对光照条件不敏感，种子硬实性是导致狼毒种子萌发率较低的主要原因，取自土壤种子库内的狼毒种子萌发率高于当年采集的种子，在自然条件下，并非每年都有狼毒种子萌发长成幼苗，种群更新时机是随机的或周期性的。

Seed germination characteristics and regeneration mechanism of Stellera chamaejasme population

Stellera chamaejasme is a perennial herbaceous plant of Thymelaceae, as one of major poisonous plant species to animal, distributing in Northeast, Northwest, and Southeast of China. In some area on the degraded steppes, the plant grew with abnormal abundance and badly endangered the health of animals. The germination capacity of Stellera chamaejasme seed that collected from soil seed bank and immediately gathered from the plant was studied under different temperature, light condition and five pretreatments (rupture seed pericarp, remove seed pericarp, soaked in 98% H2SO4 for 5 min, soaked in 0.2% KNO3 for 24 h, and kept at 10 degrees C for a week). The seed germination percentage (GP) of the plant was lower in the mass and it was 13% under constant temperature 25 degrees C with dark condition. The suitable temperatures for germination of the seeds were constant 30 degrees C or alternative 10-30 degrees C. To rupture or to remove seed pericarp could significantly increase GP and it was 49% and 47%, respectively. GP under pretreatment of seed soaked in 98% H2SO4 for 5 min was 32%. The pretreatments of seed soaked in 0.2% KNO3 for 24 h and seed kept at 10 degrees C for a week had no significantly effects on increasing GP. The seed germination was not sensitive to light condition. The hardness of the seeds was mainly responsible for the seed dormancy and low germination rate. The GP of S. chamaejasme seeds in the soil seed bank was higher than that gathered in the immediate year. Based on the comprehensive analysis with the lower GP and the results of field observation, it was concluded that S. chamaejasme seeds did not germinate every year in nature, and chance of population regeneration was random or periodic.