Optimisation of conditions for the extraction of casearins from Casearia sylvestris using response surface methodology

Optimal conditions for the extraction of casearins from Casearia sylvestris were determined using response surface methodology. The maceration and sonication extraction techniques were performed using a 3 x 3 x 3 full factorial design including three acidity conditions, three solvents of different polarities and three extraction times. The yields and selectivities of the extraction of casearins were significantly influenced by acidity conditions. Taking into account all variables tested, the optimal conditions for maceration extraction were estimated to involve treatment with dichloromethane saturated with ammonium hydroxide for 26 h. Similar yields and selectivities for casearins were determined for sonication extraction using the same solvent but for the much shorter time of 1 h. The best results for stabilisation of the fresh plant material were obtained using leaves that had been oven dried at 40 degrees C for 48 h.     

Chloroplast diversity in the genus Malus: new insights into the relationship between the European wild apple (Malus sylvestris (L.) Mill.) and the domesticated apple (Malus domestica Borkh.)

To unravel the relationship between the European wild apple, Malus sylvestris (L.) Mill., and its domesticated relative M. domestica Borkh., we studied chloroplast DNA variation in 634 wild and 422 domesticated accessions originating from different regions. Hybridization between M. sylvestris and M. domestica was checked using 10 nuclear microsatellites and a Bayesian assignment approach. This allowed us to identify hybrids and feral plants escaped from cultivation. Sixty-eight genotypes belonging to 12 other wild Malus species, including 20 M. sieversii (Ledeb.) Roem. accessions were also included in the analysis of chloroplast diversity. Marker techniques were developed to type a formerly described duplication and a newly detected transversion in the matK gene. Chloroplast DNA variation was further investigated using PCR-RFLP (Polymerase Chain Reaction-Random Fragment Length Polymorphism), and haplotypes were constructed based on all mutational combinations. A closer relationship than presently accepted between M. sylvestris and M. domestica was established at the cytoplasmic level, with the detection of eight chloroplast haplotypes shared by both species. Hybridization between M. sylvestris and M. domestica was also apparent at the local level with sharing of rare haplotypes among local cultivars and sympatric wild trees. Indications of the use of wild Malus genotypes in the (local) cultivation process of M. domestica and cytoplasmic introgression of chloroplast haplotypes into M. sylvestris from the domesticated apple were found. Only one of the M. sieversii trees studied displayed one of the three main chloroplast haplotypes shared by M. sylvestris and M. domestica. This is surprising as M. sieversii has formerly been described as the main maternal progenitor of the domesticated apple. This study hereby reopens the exciting discussion on the origin of M. domestica.     

伞形科两种植物幼苗生长对光照强度的可塑性响应

将明党参（Changium smyrnioides Wolff）和峨参（Anthriscus sylvestris Hoffm．）幼苗置于按全光照百分率为100％（S100）、65％（S65）和25％（S25）的人工控制光环境下处理。结果表明,光照强度显著影响明党参和峨参幼苗的生长：明党参在S6,生长最好,株高、冠幅、叶长、叶宽、地上地下生物量等均达到最大值,且S65的明党参生物量是S100的2倍、S25的3倍左右;而峨参地上部生长随着光照强度的减弱而增强,S25生长最好,但地下部生长则在S65生长最好,表现出与明党参同样的响应规律。明党参在不同光照强度下生长速率差异显著,S65显著高于其余两个处理;峨参虽然也在S65生长速率最大,但在不同光照强度间无差异。明党参生长速率明显小于峨参,总生物量约为峨参的1／3—1／8,相对于峨参而言明党参是一个在幼苗阶段生长缓慢的物种。     

科尔沁沙地不同密度(小面积)樟子松人工林生长状况

在内蒙古科尔沁沙地丘间片林中选择不同密度的樟子松样地,对樟子松在不同栽植密度条件下的生长情况进行了研究.由于受多年降水偏少的影响,科尔沁沙地的樟子松出现了大量枯梢继而死亡的现象,而这种现象与林地的密度存在很强的相关性.样地林木的死亡率随林地密度的加大呈幂函数关系增加,原先最高密度情况下的林地,保存到现在的活木数量反而最少;林木的平均死亡年龄、最早死亡年龄、冠幅、树高和胸径随林地密度的增加而减小.虽然在其它一些区域的研究结果表明,树高较少受竞争的影响,但是在半干旱区,树高仍然与密度相关.枯梢林木的比例在高密度的样地大于低密度的样地,枯梢对低密度样地的林木基本上没有大的影响.各样地的冠幅和胸径比相差不大,平均只有0.297,以此指标衡量,该地可能更适合单一樟子松林的种植.综合来看,科尔沁沙地的气候和土壤条件适合栽植樟子松,但初始密度应控制在2800株/hm2以下,并应根据生长情况在进入生长高峰期后对林木进行适时间伐,20a龄期的林木其密度保持在2100株/hm2左右比较适宜.     

添加氮肥对沙地樟子松幼苗生物量分配与叶片生理特性的影响

设计5个氮肥(NH4NO3)添加水平(g.m-2):0(CK)、10.0(N1)、20.0(N2)、40.0(N3)和50.0(N4),研究了沙地樟子松幼苗生长与生理学指标的季节变化。结果表明,添加氮肥促进了幼苗的高生长、相对生长速率、单株总生物量的增加,对叶片相对含水量没有影响;N4水平促进了叶片脯氨酸含量的积累。单叶重、株高、地径、叶重比、叶绿素(a b)、叶绿素a以及叶绿素b含量等均在N3水平下达到最大值。在1个生长季的观测中,添加氮肥主要促进了樟子松幼苗在5~7月份的生长,其中N3水平对樟子松幼苗生长发育的促进作用最大。     

科尔沁沙地樟子松人工林不同年龄针叶生理生态性状

樟子松(Pinus sylvestris var. mongolica)又称蒙古松, 是我国“三北”防护林建设的主要造林树种。人工林建立初期, 在水分、养分匮乏的干旱、半干旱沙地, 樟子松仍表现出较强的适应性; 近年来, 各地樟子松人工林均出现衰退迹象。在沙地这种特殊生境下, 樟子松针叶的光合作用、水分利用效率、氮利用效率等主要性状的研究对于理解樟子松的沙地适应性具有非常重要的意义。该文以位于科尔沁沙地南缘的中国科学院寒区旱区环境与工程研究所奈曼沙漠化研究站(42°55′ N, 120°43′ E) 30龄樟子松人工林为研究对象, 对不同年龄针叶的光合作用、蒸腾作用、针叶碳氮含量、针叶形态(叶长、宽、厚)等主要生理生态属性进行测定, 计算出针叶的蒸腾系数(K_c)、光合氮利用效率(PNUE), 阐明了这些性状与樟子松叶龄的关系, 进而探讨了叶片性状在樟子松适应沙地生境中的意义。结果表明, 1)不同年龄针叶的光合速率(P_n)、K_c和PNUE存在显著差异, 四龄针叶的P_n、K_c和PNUE显著低于其他龄针叶。氮含量减少是导致P_n差异的根本原因, P_n随着氮含量的减小而降低。2)各龄针叶的长、宽等形态参数及碳含量受其形成前一年的降水量影响显著。3)从水分及养分利用(K_c、PNUE)角度来看, 一至三年生针叶的利用效率更高, 四龄针叶较低。合理的叶龄结构既能增强针叶对氮素的利用又能增大植株的光合叶面积, 有利于提高个体乃至冠层的光合能力。此外, 遇到严重干旱时, 老叶脱落可以增强樟子松个体的适应性。     

半干旱区沙质退化草地造林对土壤质量的影响

采用野外调查与室内培养相结合的方法,研究了我国北方半干旱区科尔沁沙地退化草地营造樟子松人工林32年后0～10 cm表层土壤理化性状、土壤碳氮矿化量、土壤微生物量以及土壤酶活性等的变化. 结果表明32年生樟子松人工林土壤有机碳、全氮和全磷等养分含量分别下降了21%、42%和45%;5月和11月樟子松人工林土壤NH4 -N显著高于草地(P=0.001;P=0.019),而5、8和11月草地土壤NO3--N含量显著高于樟子松人工林(P＜0.001;P=0.048;P=0.031);5、8和11月樟子松人工林土壤有机碳日矿化释放的CO2-C量均大于草地,而二者土壤氮矿化率差异不显著(P＞0.05);5和8月樟子松人工林土壤微生物量碳含量与草地相比差异不显著,11月则显著高于草地;土壤养分和水分含量是影响土壤微生物量碳含量的重要因素;与草地相比,樟子松人工林土壤脲酶和蔗糖酶活性降低,而土壤过氧化氢酶活性升高. 上述结果说明半干旱区沙质退化草地营造樟子松人工林32年后土壤质量出现一定程度的下降;由于植被的改变,樟子松人工林土壤理化性状和生物学性状等表现出与草地不同的季节动态特征.造林作为我国北方半干旱区沙地退化生态系统的一种恢复手段具有一定的局限性.     

Variation in aboveground net primary production of diverse European Pinus sylvestris populations

On range-wide and regional scales, climate and site factors exert control over tree growth, masking the genetic basis of biomass accumulation and allocation. To determine intrinsic population differences in productivity, aboveground net primary production (ANPP) was measured in 16-year-old Scots pine from 19 geographically distinct populations grown in a common garden experiment in central Poland (52°N). The populations originated from the northern (>55°N), central (54–47°N), and southern (<45°N) European range of Scots pine. We calculated ANPP from aboveground growth components, using diameter-based allometric equations developed for this site. Average foliage, aboveground woody and total ANPP differed significantly among populations and were greater for central European populations than for the southern and northern ones. Stocking and total ANPP per tree were positively correlated to stand aboveground biomass (r ²≥0.71). The relationship between the latitude of seed origin and ANPP was curvilinear and maximum for populations originating near the planting site (52°N). ANPP declined in populations with increasing longitude eastward from the Atlantic Ocean towards the center of the continent. This study underscores the potentially large genetic control of ANPP and biomass accumulation among diverse Scots pine populations. Received: 3 January 2000 / Accepted: 29 March 2000     

Seed mass versus seedling performance in Scots pine: a maternally dependent trait

It is generally accepted that larger seeds give rise to seedlings with better performance. On the other hand, the size that a seed reaches is genetically determined by at least two different traits ; the genetic variability of the developing embryo and the genetic variability of the maternal plant. Thus, the relative contributions of these two traits affect seedling performance by influencing seed size. In this paper, I investigate the effect of seed size on seedling performance in the Scots pine ( Pinus sylvestris ). From eight maternal plants, 50 seeds were planted in each of two soil types (800 seeds in total), and seedling performance was monitored for 1 yr. Seed mass proved to be highly constant within maternal plants. Soil type influenced emergence and survival; however, the effect of soil type differed depending on maternal origin. Seed mass was positively correlated with seedling emergence, although this relationship was not found for seedling survival or date of emergence. The initial growth of the shoot was also positively correlated with seed mass. However, after one growing season, seed mass had no effect on seedling performance, which depended exclusively on maternal origin. Nevertheless, the mean mass of seeds produced by plants was positively correlated with mean values of growth parameters. Thus, first-year seedling performance seems to be a maternal trait indirectly associated with seed size.