Organic residue mass at planting is an excellent predictor of tree growth in Eucalyptus plantations established on a sandy tropical soil

Tropical plantation forests are meeting an increasing proportion of global wood demand and comprehensive studies assessing the impact of silvicultural practices on tree and soil functioning are required to achieve sustainable yields. The objectives of our study were: (1) to quantify the effects of contrasting organic residue (OR) retention methods on tree growth and soil nutrient pools over a full Eucalyptus rotation and (2) to assess the potential of soil analyses to predict yields of fast-growing plantations established on tropical sandy soils. An experiment was set up in the Congo at the harvesting of the first rotation after afforestation of a native herbaceous savanna. Six treatments were set up in 0.26 ha plots and replicated in 4 blocks, with OR mass at planting ranging from 0 to 46.5 Mg ha⁻¹. Tree growth over the whole rotation was highly dependent on OR management at planting. Over-bark trunk volume 7 years after planting ranged from 96 m³ ha⁻¹ in the treatment with forest floor and harvest residue removal at planting to 164 m³ ha⁻¹ in the treatment with the largest amount of OR. A comparison of nutrient stocks within the ecosystem at planting and at the end of the rotation suggested that nutrient contents in OR were largely involved in the different response observed between treatments. OR management treatments did not significantly modify most of the nutrient concentrations in the upper layers of the mineral soil. Conventional soil analyses performed before planting and at ages 1 and 3 years were unable to detect differences between treatments despite large differences in tree growth. In contrast, linear regressions between stand aboveground biomass at harvesting and OR mass at planting (independent variable) showed that OR mass was an excellent predictor of stand yield (R² = 0.99). A large share of soil fertility comes from organic material above the mineral soil in highly weathered sandy soils and OR mass at planting might be used in conjunction with soil analyses to assess the potential of these soils to support forest plantations.     

Effect of heme oxygenase-1/endogenous carbon monoxide system on restenosis of rabbit carotid artery after balloon injury

AIM: To investigate the effect of heme oxygenase-1 (HO-1)/carbon monoxide (CO) system on restenosis of carotid artery after balloon angioplasty.METHODS: Fifty rabbits were randomly divided into 5 groups: control group given normal chow (C group), sham group(Sh group), 1.5% cholesterol diet group (Ch group), 1.5% cholesterol diet plus hemin group(Hm group)and zinc protoporphyrin IX group(Zn group).The experiment lasted for 10 weeks. At the beginning of the 3rd week, the animals in Ch group, Hm group and Zn group underwent balloon injury at one side of common carotid artery.RESULTS: Compared with those in C group, the production of arterial nitric oxide (NO) and activity of constructive nitric oxide synthase (cNOS) were significantly decreased, while CO production and HO-1 expression were significantly increased (all P<0.01) in Ch group. Compared with those in Ch group, the arterial CO production and HO-1 expression in Hm group were markedly increased, while the expression of endothelin-1 (ET-1), the intimal area and the ratio of intimal area/medial area(I/M) were distinctly reduced. Compared with those in Ch group, the arterial CO production and HO-1 expression in Zn group were obviously decreased, while the expression of ET-1, the intima area and the ratio of I/M were significantly increased.CONCLUSION: The HO-1/CO system improves the endothelium function and restrains neointimal proliferation by compensating and regulating NOS/NO system and lowering ET-1 expression so as to inhibit the restenosis.     

稻瘟病菌ABC转运蛋白基因中 SSR的分布及其功能预测

 ABC转运蛋白在真菌的致病性方面起着重要的作用。本研究查找和分析了稻瘟病菌基因组中47个ABC转运蛋白基因的外显子区、内含子区、5′-UTR和3′-UTR区中的SSR,并对编码区中SSR的扩张或收缩对蛋白结构的影响进行了预测。结果表明,SSR在这些基因的调控区和编码区分布不均一,且在基因的外显子区、内含子区、5′-UTR和3′-UTR区中SSR的组成和分布均不相同;基因的编码区中三碱基和六碱基SSR相对较多,SSR的基序大都表现为GC含量较高,编码的亲水性氨基酸出现频率远远高于疏水性氨基酸。根据稻瘟病菌自然群体中SSR的变化幅度,预测了SSR的扩张或收缩对蛋白二级结构的影响,发现SSR的扩张或收缩都可能对蛋白的结构产生影响。暗示着SSR的变异在致病相关基因的变异中可能扮演着重要角色。     

高效降解有机磷农药真菌的分离鉴定及其特性研究

从有机磷农药严重污染的土壤中分离筛选出有机磷农药高效广谱降解真菌,并对其进行鉴定及降解特性研究。通过有机磷农药驯化培养、形态学和生理生化特性及其18S rDNA序列分析等试验对其进行初步鉴定,研究外界因素初始pH、培养温度、氧化乐果初始浓度等对降解菌的生长量和降解能力的影响。通过驯化分离筛选等过程从污染土壤中筛选到2株可以在高浓度氧化乐果环境下生长的真菌J4和J6,它们经生理生化和18 S rDNA序列测定初步鉴定均为黑曲霉（Aspergillus niger）。研究发现,J4和J6菌株在氧化乐果初始浓度1000 mg/L,pH值分别为6.5和6.0,温度分别为30℃和28℃,摇床转速160 r/min条件下,培养5天后降解菌可达到最佳生长量和降解能力,降解率可分别达77.83%和70.81%,耐受氧化乐果的最大浓度均为5000 mg/L,其生长量和降解能力具有正比例相关性变化趋势;并进一步研究发现,曲霉J4和J6还具有广谱降解有机磷农药的特性。     

西瓜花药培养技术研究进展

花药培养是作物育种中一种重要的辅助育种技术。文章对影响西瓜花药培养的主要因素,如基因型、小孢子发育时期、培养基、碳源、生长调节剂、活性炭、三十烷醇等研究进展进行了综述,并针对西瓜花药培养中存在的问题提出了今后研究的方向。     

Changes in bioactive compounds and antioxidant activities in pomegranate leaves

Pomegranate leaves are an important source of potentially healthy bioactive compounds. Changes in total phenolics, flavonoids, alkaloids and antioxidant activities in pomegranate leaves were recorded from April 18th to September 16th, 2007. Total levels of phenolics and flavonoids decreased significantly in the early stages of leaf growth, and then increased gradually until the end of September. However, concentrations of total alkaloids increased during leaf growth and development. Antioxidant activities in pomegranate leaves were significantly correlated with the level of total phenolics and flavonoids. All bioactive compounds measured from pomegranate leaves increased during leaf growth and development. These trends suggest that the optimum picking time for tea is before May and bioactive compounds should be extracted from pomegranate leaves after August.     

碳源及植物生长调节剂对亳芍愈伤组织生长和芍药苷积累的影响

[目的]研究不同碳源和植物生长调节剂对亳芍愈伤组织生长和芍药苷积累的影响。[方法]以亳芍根茎为外植体,改变培养基中碳源(蔗糖、果糖、葡糖糖、麦芽糖、可溶性淀粉)和植物生长调节剂种类(6-BA、NAA、2,4-D),考察亳芍愈伤组织增长量和芍药苷积累量。[结果]碳源中,对亳芍愈伤组织的增长量以蔗糖最高,葡糖糖最有利于芍药苷积累;组合使用植物生长调节剂6-BA、NAA和2,4-D比单独使用6-BA更有利于愈伤组织生长和芍药苷积累,但高浓度的2,4-D抑制愈伤组织生长和芍药苷积累。[结论]确定了亳芍愈伤组织生长和芍药苷积累的最佳碳源和植物生长调节剂组合,为葡萄糖30 g/L+6-BA 0.5 mg/L+NAA 0.2 mg/L+2,4-D 0.2 mg/L。     

热带次生林演替过程中环境因子对物种多样性的影响

为了解热带森林次生演替的群落环境特征变化对植物多样性的影响,以两种不同演替阶段的热带滨海次生林群落为研究对象,采用两种非参数检验以及Kendall秩相关分析的方法,对两群落内部的环境因子及其对植物多样性、均匀度以及物种周转率的影响进行研究。结果表明:各环境因子在群落间和群落内均存在差异。在热带常绿季雨林(TEMF)、灌木林(SHR)内,光合有效辐射(PAR)对物种多样性和周转率有显著影响。在两个群落内,土壤相对湿度对物种分布均起到重要影响,对SHR中物种分布的影响更强。在TEMF中,土壤温度、坡度及坡位对物种多样性和周转率限制显著;在SHR中,空气相对湿度成为限制物种分布的主要环境因子。     

辽东山区紫椴、花曲柳碳素积累及主要营养元素分布特征1）

以辽东山区天然阔叶混交林重要组成树种紫椴和花曲柳为研究对象,通过生物量实测法,探究紫椴和花曲柳的碳素积累的变化特征以及不同器官氮（N）、磷（P）、钾（K）元素的分配格局。结果表明：花曲柳树干的平均固碳量和连年固碳量整体上高于紫椴,随林龄的增长差距有逐渐增大的趋势;40年生花曲柳树干平均碳素密度为322．18 kg· m－3,36年生紫椴为272．63 kg· m－3。在养分分配方面,紫椴和花曲柳单株N、P、K元素的积累量顺序一致（N＞K＞P）,但在不同器官中各元素积累顺序有些差异。紫椴各器官养分积累总量顺序为：树干＞树根＞树枝＞树叶;花曲柳各器官养分积累总量顺序为：树根＞树干＞树枝＞树叶。紫椴与花曲柳树叶的养分归还量占各自总体的比例分别为4．11％和17．32％,而树叶、树枝与根的养分积累比重合计分别为57．07％和75．31％,三者在生态系统养分循环中占有重要作用。     

杂种落叶松家系变异分析与多性状联合选择

以黑龙江省铁力市丰林林场杂种落叶松家系试验林为研究对象,对生长性状、材性性状、生物量、碳储量进行调查分析,首先利用标准木数据进行生物量方程拟合,得到杂种落叶松家系生物量方程。变异分析结果显示:杂种落叶松家系生长性状、生物量、碳储量存在较丰富的变异,材性性状变异相对较小。碳储量方面:日3×兴9、日5×长77-3、日11×兴2、兴5×兴9这4个家系变异较大。利用方差分析与多重比较等方法对杂种落叶松家系间差异性进行比较,结果显示:生物量、碳储量、木材密度家系间差异达到显著水平,碳储量方面,兴6×长6、兴7×日77-2、兴12×兴2、兴9×日76-2这4个家系相比其它家系表现优异,4个家系的平均值比总平均值高出18.82%,高出对照(CK)为20.74%,高出杂种混30.35%,高出长白落叶松小北湖与白刀山种源分别为35.40%和43.56%,高出兴安落叶松乌伊岭种源41.62%,高出长白落叶松自由授粉家系长73-18与长73-4分别为20.74%和30.35%。对杂种落叶松参试家系各性状值进行主成分分析,将生长、材性、碳储量等性状进行综合分析,多性状联合选择优良家系,最终选择兴6×长6、兴7×日77-2作为杂种落叶松优良家系。