中国东北样带（NECT）羊草种群数量特性变化及其与环境因子的直接梯度分析

陆地样带研究是国际地圈一生物圈计划( IGBP)全球变化研究中最引入注目的创新之一。目前，国际上已经设立了15条陆地样带，而且正在开展各项研究工作。现有关于陆地样带的研究报道多集中在环境梯度分析、气候变化对植被初级生产力的影响及环境变化与植被变化的对应关系等方面，而关于陆地样带环境梯度变化上植物种群生态学的研究尚未见报道。 本研究以东北样带为平台，研究北纬43。31' - 44041'，东经125018’-115。31'范围内，即由湿润到干旱的环境梯度变化系列，羊草主要形态特征、种群密度、生物量、种子生产、生物量分配比例等变化规律及其与环境因子的相关关系，初步探讨了中国东北大尺度环境变化对羊草种群的影响及羊草对变化环境的适应规律。 在本研究的环境变化系列上，羊草种群外部形态的突出变化是种群植株高度由东至西沿降水量逐渐下降的梯度逐级递减，而且植株高度与生长季前期的降水量呈显著正相关关系。除旗叶外，羊草种群各叶片长度具有相似的变化趋势，即长春地区种群叶片长度远远大于其它种群，阿巴嘎旗地区种群叶片长度远远小于其它种群，其它8个种群叶片长度变化不大，呈平缓波动状态。除长春地区羊草叶片宽度显著大于其它种群外，其它9个种群间虽有一定的差异，但基本是处于波动状态。这说明羊草的各形态特征对该梯度环境变化的反映是不同的。 在该环境梯度上，羊草种群总密度、营养枝密度和生殖枝密度具有非常相似的变化趋势，均为由东至西呈先增后减的趋势，并且最大值都在长岭种马场地区。而且，无论是种群总密度，还是营养枝和生殖枝密度均与9月份平均温度显著相关，这是因为秋季高温对地上部分的营养物质向地下根茎转移及地下根茎芽的形成有利，丰富的物质积累和发育良好的地下根茎芽是翌年种群具有较高密度的保障。在本研究的10个种群中，除长春地区种群生殖枝分化率显著低于其它种群外，各羊草种群生殖枝分化率相对稳定，而且羊草种群生殖枝分化率与环境梯度上各环境因子间的相关性均不显著。 在本研究中，种群总生物量、营养枝生物量、生殖枝生物量和个体生物量等指标具有不同的变化趋势。表现为由东至西或由湿润到干旱，除生殖枝生物量在最东端的各种群中呈增加趋势外，种群总生物量和地上群体生物量（营养枝生物量和生殖枝生物量）均呈逐级盘低走势，而且干燥系数和生长季前期的降水量是决定总生物量和地上群体生物量变化的主要因素。地下根茎生物量表现为从湿润的长春市地区到半干旱的绍根地区呈缓慢盘低，而后随干旱程度的加重迅速增加，但至最干旱的阿巴嘎旗地区又迅速下降。在半干旱和干旱地区，植物根系生物量增加能使植物更有效地利用有限的水资源。羊草种群个体生物量的变化趋势基本一致，即除长春地区种群个体生物量远远大于其它9个种群外，各羊草种群个体生物量虽有所差异，但变化不大，基本水平波动状态。个体生物量的相对稳定是羊草能适应各种变化生境的重要保障，而且在该实验梯度上个体生物量的相对稳定是通过种群密度变化来调节的。 在本研究梯度上，虽然各种子生产指标有一定的变化，如锡林郭勒草原定位站种群和阿巴嘎旗种群的种穗长度、结实数和单位面积种子产量均较低等，但这些指标的变化与由东至西的降水量递减等气候因子变化是不一致的，如结实数、单位面积种子产量和种子重量等基本呈波动状态，只是在实验梯度的西端才有明显的下降。这说明在本研究的环境梯度系列上，环境因子对羊草种子生产有一定的影响，但最主要的影响可能是其自身遗传因素，这有待于今后的深入研究。 在本研究的环境梯度上，由东至西或由湿润到干旱的气候变化系列上，羊草种群根茎、营养枝、生殖枝和种子生物量分配比例呈现明显的规律性变化。最显著的表现是羊草种群根茎生物量分配比例随降水量的减少而逐渐增加。在水资源有限的生境下，大比例的根茎生物量分配能增加根系对地下水分的吸收，同时有利于物质和能量在根部的贮藏，这种机制能确保植物在干旱气候条件下生存。相反，羊草种群地上营养枝生物量分配比例由东至西逐渐下降，减少营养枝生物量分配比例可以降低营养枝水分蒸腾量，协调根部水分吸收和枝条蒸腾的关系，保持整个植物体的水分平衡。羊草种群生殖枝和种子生物量分配比例均呈两头低，中间高的变化趋势。这说明降水充足和严重干旱均不利于羊草有性生殖体的生产，半湿润和半干旱气候区是羊草种子生产的理想地域，这也可能是羊革能在半湿润和半干旱气候区大面积分布的原因。

欧报春(Primula vulgaris)不同花色与色素关系及花色遗传初步分析

为了掌握欧报春各花色遗传规律服务于良种生产,通过对欧报春各色花进行色素吸收光谱和薄层层析分析,进行不同花色杂交研究,分析了欧报春各色花所含色素类型及各花色遗传规律。结果显示欧报春群体含多种花色素,单株也可含有多种花色素,形成多变的粉色、红色及蓝色花。黄色深浅主要由类胡萝卜素含量决定。白色对粉色及黄色为隐性遗传,黄色、粉色为显性遗传并有数量遗传特征,黄色与粉色独立遗传。蓝色为多基因控制的隐性遗传,并具有数量遗传特征。

Effects of effective population size on the F-2 growth and survival of bay scallop Argopecten irradians irradians (Lamarck)

In 2002, six cohorts of broodstock bay scallop Argopecten irradians irradians (Ne=1, 2, 10, 30, 50 and control) were randomly chosen from a population of bay scallop to produce offspring. After one year rearing, with the progeny matured, the similar experiment was done to produce the F-2 generation. To determine the magnitude of Ne effects, the growth and survival rates in larvae and adult of six F2 groups were compared. Results showed that inbreeding depression existed not only in the Ne=1 group but also in the Ne=2 group. The growth and survival rates of the two groups were significantly lower than those of the other groups (Ne=10, 30, 50, control), and there were no significant differences among the latter (P>0.05). At the same time, the amount of depression in the Ne=1 group was significantly higher than that of the Ne=2 group (P<0.05). These results indicated that the low effective population size (Ne), which increases the possibility of inbreeding, could lead to some harmful effects on the offspring. So it is essential to maintain a high level of Ne in commercial seed production. Furthermore, as the high fecundity of bay scallop might lead to increased inbreeding, selecting broodstock from different growout sites is recommended.

Interannual fluctuations in floral longevity, pollinator visitation and pollination limitation of an alpine plant (Gentiana straminea Maxim., Gentianaceae) at two altitudes in the Qinghai-Tibetan Plateau

Prolonged floral longevity and bumblebees as dominate pollinators in alpine ecosystem have been suggested to overcome pollination limitation of alpine plants arising from the decrease of pollinator activity with increasing altitude. However, this conclusion has never been examined in the Qinghai-Tibetan Plateau (QTP), the highest and largest plateau in the world. In this study, we intended to test year-to-year correlations between floral longevity, visiting frequency and pollen limitation of this species between two populations (at 3200 m and 4000 m) of Gentiana straminea in this plateau. Pollinator exclusion elongated both male and female phases greatly at both sites, and durations of both male and female phases in natural condition varied greatly over three years. The visiting frequency of bumblebees varied greatly at the higher altitude, but seemed to be stable at the lower altitude. Seed production was pollination limited in both populations in most studied years. The floral durations, pollinator frequency and pollination limitation showed no significant and consistent variations with the increase of altitude. The previous hypothesis that the prolonged floral longevity of alpine plants can compensate for low levels of pollinator visitation therefore could not be confirmed, and our results further suggested that in the QTP platform, the altitude shows no consistent effect on the reproductive performance of this species, despite that the fluctuation of visit frequency intensified at the higher altitude.

Pollinator shift and reproductive performance of the qinghai-tibetan plateau endemic and endangered Swertia przewalskii (Gentianaceae)

Reproductive failure results in many plant species becoming endangered. However, little is known of how and to what extent pollinator shifts affect reproductive performance of endangered species as a result of the artificial introduction of alien insects. In this study we examined breeding systems, visitor species, visiting frequency and seed set coefficients of Swertia przewalskii in two years that had different dominant pollinator species (native vs. alien). Flowers of this species were protandrous and herkogamous and insects were needed for the production of seeds. The stigmatic receptivity of this species was shorter than for other gentians. No significant difference in seed set coefficient was found for hand-pollinated plants between the two years, indicating that pollinator shift only had a minor effect on this plant's breeding system. The commonest pollinators in 2002 were native bumblebees, alien honeybees and occasional solitary bees, however, only alien honeybees were observed in 2004. The flower visitation rate in both years was relatively high, although the total visit frequency decreased significantly in 2004. The control flowers without any treatment produced significantly fewer seed sets in 2004 than in 2002. In the past decade the seed production of this species may have partly decreased due to pollination by alien honeybees, however, we suggest that they might have acted as alternative pollinators ensuring seed production of S. przewalskii when native pollinators were unavailable. The main reason that this plant is endangered is probably the result of habitat destruction, but changes in land use, namely intensified agricultural practice and unfavorable animal husbandry have also contributed to its decline. We recommend that in-situ conservation, including the establishment of a protected area, is the best way to preserve this species effectively.

Control of cocklebur seed germination by nitrogenous compounds : Nitrite, nitrate, hydroxylamine, thiourea, azide and cyanide

Germination of non-dormant upper cocklebur (Xanthium pinsylvanicum Wallr.) seeds was stimulated by not only CS(NH2)2 but also NH2OH, KCN and NaN3. This stimulation was not via the enhancement of aerobic C2H4 production. NH2OH, KCN and NaN3 in certain concentrations promoted the initial growth of axial and/or cotyledonary parts, but the degree of growth promotion by NH2OH, NaN3 and KCN was slight compared with that by CS(NH2)2. As in the case of CS(NH2)2, however, the germinationstimulating effect of NH2OH disappeared rapidly as the preceding imbibition period was prolonged. In contrast, KCN and NaN3 were still effective in stimulating the germination of aged seeds maintained on a water substratum, as previously seen with anaerobiosis. Anaerobic induction was enhanced not only by NaN3 and KCN but also by NH2OH, KNO3, KNO2 CO(NH2)2 and CS(NH2)2 applied during the anaerobic treatment, but without causing an increase in anaerobic production of C2H4. Furthermore, KCN and NaN3, given prior to the anaerobic treatment acted additively with anaerobic induction. The germination-stimulating actions of nitrogenous compounds are discussed in comparison with those of C2H4 and anaerobiosis.