超声波辅助提取千斤拔中总黄酮的工艺研究

[目的]优选超声波法提取千斤拔中总黄酮的最佳工艺条件。[方法]以总黄酮提取率为评价指标,采用单因素和正交试验确定超声波辅助提取千斤拔总黄酮的工艺条件。[结果]最佳的超声提取条件为乙醇浓度为80％,提取时间为25min,料液比为．1：20（g／ml）,提取次数为2次;在此条件下,千斤拔总黄酮的得率为3．00％。[结论]确定了超声波辅助提取千斤拔总黄酮的最佳工艺条件,为千斤拔资源的合理开发利用提供了理论依据。     

大叶山杨与山杨形态及物候特征比较

应用形态特征对比、孢粉学、树木的物候观测等方法对山杨、大叶山杨的差异进行了比较.结果表明：山杨、大叶山杨形态与物候特征差异显著.据此,对大叶山杨分类地位进行了讨论.     

大叶山杨幼化处理技术的研究

以大叶山杨的超级实生苗的当年生枝条、成年优树根部萌条当年生嫩枝和成年优树树冠当年生嫩枝切段做外植体,采用连续继代培养和微型嫁接法进行幼化处理技术研究。结果表明：随连续继代次数的增加及微嫁接后再继代次数的增加,茎条的幼化程度随之提高,徽扦插生根率也在提高。成年优树根部萌条当年生嫩茎连续继代4～5次,微扦插生根率可达100%;成年优树树冠当年生嫩茎连续继代6～7次,微扦插生根率可达100%;用组培苗作砧木微嫁接后再进行微繁,连续继代3～4次,微扦插生根率可达100%。     

正交设计法优化宁夏六盘山区产秦艽水提工艺

[目的]优化宁夏六盘山区产秦艽的最佳水提工艺。[方法]以测定秦艽中龙胆苦苷提取率作为考察指标,采用L9（3^4）正交试验,考察提取水量、提取时间、提取次数、提取温度对龙胆苦苷提取率的影响。[结果]各因素对检测指标影响大小顺序是：提取次数〉提取温度〉提取水量〉提取时间,最佳水提工艺为当秦艽质量为0．5g时,溶剂用量为15ml,提取时间为45min,提取次数为3次,提取温度为30℃。[结论]提取次数对龙胆苦苷提取影响显著。     

分光光度法测定蔓性千斤拔中总黄酮的含量

[目的]研究可见光及紫外分光光度法测定来自不同产地的蔓性千斤拔中总黄酮含量的方法。[方法]可见光分光光度法是以芦丁为参照品,硝酸铝作显色剂,在510 nm波长处测定总黄酮的含量。紫外分光光度法是以芦丁为参照品,在355 nm波长处测定总黄酮的含量。[结果]可见光法平均回收率是99.68%,RSD为1.37%;紫外光法是99.07%,RSD是0.94%。[结论]紫外分光光度法是一种较理想的测定蔓性千斤拔中总黄酮含量的方法。     

紫阳花组培繁殖技术研究

以紫阳花的茎段、茎尖、叶片为外植体,在MS培养基中加入不同质量分数的6-苄基腺嘌呤(6-BA)和吲哚丁酸(IBA)进行增殖培养.结果表明:外植体表面灭菌是一个重要环节,适宜紫阳花外植体表面灭菌方法是:利用0.1％氯化汞(HgCl2)灭菌7min.不同类型的紫阳花外植体在初代培养时增殖效果不同,茎尖在培养过程中,首先伸长生长,然后陆续长出侧芽,表明紫阳花的茎尖是比较适合用来进行增殖培养的外植体.继代培养时以MS+6-BA 1.0 mg/L+IBA0.1 mg/L为紫阳花较适宜的增殖培养基.紫阳花侧芽在1/2MS+IBA 0.2 mg/L培养基中生根率和单苗根数量均较高,说明1/2MS+IBA 0.2 mg/L为较好的不定根诱导培养基.     

盆栽八仙花潮汐灌溉栽培试验初探

采用潮汐灌溉方式,对盆栽八仙花所需水量和灌溉时间进行智能化管理研究.结果表明:八仙花潮汐灌溉栽培与滴灌灌溉生长发育差异明显,其中八仙花潮汐灌溉栽培比滴灌栽培节水33％,且生长迅速,花品质好,可提高水分利用率,减少用水量,减轻劳动强度,并可实现对水分和营养液的循环再利用.     

Impact of contour hedgerows on upland maize yields in the Philippines

An agricultural production function is used to examine the yield impacts of contour hedgerows constructed using double rows of the N₂-fixing species Desmodium rensonii and Flemengia macrophylla. The analysis uses data from a sample of upland Philippine maize farms and controls for input use and plot characteristics. Results support a hypothesis that the long-run impact of hedgerows on maize yields is positive. However, results suggest that in the short run, hedgerows not only reduce area available for cultivation on a plot, but also reduce the performance of corn in the remaining alleys. For newly established hedgerows an increase in hedgerow area is associated with a reduction in maize yield. The time required for hedgerows to compensate for the area they occupy is found to be approximately eight years. This revised version was published online in August 2006 with corrections to the Cover Date.     

Weed biomass dynamics in planted fallow systems in the humid forest zone of southern Cameroon

Interest in planted fallow systems has focused on soil fertility improvement, neglecting other potential benefits of such systems. It is important to quantify other processes responsible for crop yield increases under planted fallows, such as weed control. The suppressive potential on weeds of Flemingia macrophylla [(Willd.) Merrill] and Pueraria phaseoloides (Roxb.) Benth, planted fallows was evaluated in field trials in three villages in southern Cameroon. In each village, experiments were set up in 4–5 year-old bush fallow dominated by Chromolaena odorata (L.) R. M. King & H. Rob. and 20 year-old secondary forest. Total aboveground biomass production of P. phaseoloides was 7.45 Mg ha⁻¹, 4.2 times higher than F. macrophylla (1.78 Mg ha⁻¹ ; P < 0.05). The high biomass of P. phaseoloides resulted in a significantly greater reduction in total weed biomass compared to Flemingia macrophylla in both wet and dry seasons. In the wet season (11 and 18 MAP), there were significant fallow system × land use and fallow system × village interactions for total weeds and broadleaf weeds. P. phaseoloides in bush (0.55 Mg ha⁻¹), and P. phaseoloides at Ngoumou (0.09 Mg ha⁻¹) had the lowest total weeds in the wet seasons. After the dry season, the lowest total weed mass was consistently recorded in P. phaseoloides while the highest was in the natural regrowth. The population of grasses was always higher in the F. macrophylla system than in P. phaseoloides system throughout the wet and dry seasons. Grass biomass in the P. phaseoloides-forest LUS was the least (0.01 Mg ha⁻¹), 58 times lower than in F. macrophylla-bush (0.58 Mg ha⁻¹). Biomass production of P. phaseoloides was highly significantly correlated with total weed biomass (r = −0.64; P = 0.004) while no relationship was found between biomass production of F. macrophylla and total weed biomass (r = −0.08, P = 0.747). It was concluded that P. phaseoloides was a suitable leguminous species for weed control. But for F. macrophylla, its low biomass production coupled with a compact plant architecture compromised it as an appropriate species for weed control in a planted fallow system.     

Competition for light between hedgerows and maize in an alley cropping system in Hawaii, USA

Successful agroforestry systems depend on minimizing tree-cropcompetition. In this study, field experiments and a simulation model were usedto distinguish between tree-crop competition for light and belowgroundcompetition in an alley cropping system. Maize (Zea maysL.) was harvested periodically in three treatments: between vertical barriers ofshade cloth, hedgerows of Flemingia macrophylla (Willd.)Merr., and sole maize. Radiation intercepted by the maize was calculated using asimulation model based on measured values for direct and diffuse light, hedgerowdimensions and leaf area, and solar trajectory. Radiation use efficiency wascalculated as biomass production per unit of intercepted radiation. Maizebiomass and yield in both the alley crop and the shade cloth treatment weregreatest in the center of the alleys. Grain yield between hedgerows was 3.5Mg ha⁻¹ (averaged across the alley), significantlyless than in the shade cloth (7.4 Mg ha⁻¹) or thesole maize (7.7 Mg ha⁻¹) treatments. Lightintercepted by the maize in the alley crop was about half that intercepted bythe maize in the sole crop. The shade cloth intercepted less light than thehedgerows because it did not have an appreciable width. Radiation use efficiencyin the three treatments was 0.75 g mol⁻¹ PAR anddid not differ significantly among treatments. Tree-crop competition wasoverwhelmingly for light. This revised version was published online in June 2006 with corrections to the Cover Date.