氮素营养对美丽异木棉等4个树种幼苗生长及光合特性的影响

为了探索不同氮素供应水平对美丽异木棉等4个树种的苗期生长以及光合生理特性的影响,采用指数施肥法对4个树种幼苗进行施肥试验。结果表明：（1）不同氮素处理间幼苗生长差异显著,各生长指标受氮素影响较大的是生物量和苗高,地径的变化幅度最小;（2）不同氮素处理间幼苗光合生理指标有显著差异,随着氮素施用量的增加,美丽异木棉的净光合速率呈现出先增加后减小的趋势,气孔导度和胞间CO2浓度呈现出“减小-增加-减小”的趋势,蒸腾速率呈现2次先增加后减小的趋势;杜鹃红山茶、红花荷和火焰木的净光合速率、气孔导度及蒸腾速率呈现出2次先增加后减小的趋势。     

Maize and sesbania production in relay cropping at three landscape positions in Malawi

The relay cropping of sesbania (Sesbania sesban) — a N₂-fixing legume — with maize (Zea mays) has been proposed as a strategy to increase soil fertility and food production in densely populated areas in southern Africa. We determined the production of relay-cropped maize and sesbania at three landscape positions under researcher-designed and farmer-managed conditions in southern Malawi. Three landscape positions (dambo valley or bottomland, dambo margin with < 12% slope, and steep slopes with > 12% slope) were examined in factorial combination with N sources for maize (no added N, relay-cropped sesbania, and calcium ammonium nitrate fertilizer). Relay cropping of sesbania with maize increased maize grain yield, as compared to unfertilized sole maize in two of three years. Split application of 96 kg N ha^–1 as N fertilizer, however, was more effective than sesbania in increasing maize yields. Survival of sesbania seedlings and biomass production of sesbania were greater in the dambo valley and dambo margin than on steep slopes. Maize yields tended to be lower on steep slopes than in the dambo valley and dambo margin areas. Biomass production of sesbania and hence the potential benefits of intercropping sesbania with maize appear greater in the dambo valleys and dambo margins than on steep slopes.This revised version was published online in November 2005 with corrections to the Cover Date.     

Agroforestry and forestry on the Cape Verde Islands

The geography, socio-economy, climate and agriculture of the Cape Verde Islands are introduced. Forestry and agroforestry provenance trials are described for coastal and inland areas in the semi-arid climate of Cape Verde. Sesbania sesban var. nubica showed promise as a drought tolerant, fast growing agroforestry species and Acacia bivenosa is recommended for soil stabilisation of exposed coastal areas. At a saline coastal site Atriplex lentiformis and A.halimus were the fastest growing of seven Atriplex species.     

RP-HPLC法同时测定宣木瓜中2种三萜酸及其比例

本研究建立了同时测定宣木瓜中2种三萜酸的含量及其比例的反相高效液相色谱法。Phenomenex C18色谱柱(250mm×4.6mmi.d.,5μm);柱条件为:柱温25℃;进样量5μL,检测波长210nm。对流动相和流速及精密度展开探讨,同时,采用去杂纯化对测定精密度进行比较研究。研究结果表明:流动相为V乙腈:V纯净水=95:5,流速为0.5mL/min时,齐墩果酸和熊果酸进样量在0.4～2μg范围内,线性关系良好,回归方程分别为:Y=7414804.000X+176597.400,(R2=0.9994);Y=8315634X-2681.667,(R2=0.9998)。得到的2种三萜酸的纯度为93.56%,齐墩果酸和熊果酸的平均回收率分别为98.6%和96.9%,RSD值分别为0.42%和1.2%;2种三萜酸的比例为(2.14～2.22):1,RSD值为1.39%。本方法操作简便,精密度高,重复性好,适用于宣木瓜及其相关原料中齐墩果酸和熊果酸同时定量分析。     

重瓣大岩桐叶片离体培养高频植株再生体系的建立

以重瓣大岩桐叶片为外植体进行离体培养再生体系研究.结果表明:以新展开的嫩叶为外植体最好,芽分化率达96.67%;叶片通过脱分化和再分化直接产生不定芽.6-BA和NAA适宜的配比均可促进芽的诱导和增殖,IBA有利于根的生长;MS 6-BA 2.0mg/L NAA 0.2 mg/L培养基最适合芽的诱导,诱导率达96.55%;增殖培养以带芽愈伤团效果较好,在MS 6-BA 2.0mg/L NAA 0.2 mg/L LH 500 mg/L培养基中,增殖系数达18.在1/4MS IBA 0.5mg/L培养基中生根率高达100%.炼苗移栽成活率达92%.     

贮藏温度和时间对木棉与美丽异木棉种子活力的影响

利用木棉 Bombax ceiba 和美丽异木棉Chorisia speciosa混合种子,在0、4、和8℃条件下贮藏135d,每隔45 d测定一次种子场圃发芽率和活力指标,用2,3,5-三苯基氯化四氮唑法(TTC法)测定种子的初始和贮藏135 d的生活力。结果如下:木棉种子在相同贮藏温度条件下,随贮藏时间的延长,发芽率、发芽势、活力指数存在显著差异(P<0.05),贮藏温度和贮藏时间有极显著的交互作用,种子活力逐渐下降,贮藏135 d后种子发芽率在8.33%以下,基本失去发芽能力;美丽异木棉种子在不同温度下,随着贮藏时间延长,发芽率、发芽势、活力指数没有显著差异,贮藏温度和贮藏时间没有显著的交互作用,种子发芽率为新鲜种子发芽率的67.46%以上;利用TTC染色法(1.0%浓度)能反映出木棉的种子生活力;木棉种子0℃贮藏90 d发芽率好于4和8℃,可在生产中推广应用TTC染色法检测木棉的种子生活力;美丽异木棉种子0、4、8℃贮藏135 d的发芽率差异很小,0℃贮藏发芽率和活力指数较优。     

不同栽培基质对牛大力根系发育的影响

以不同比例泥土、砂、椰糠、草炭混合作为牛大力栽培基质,并进行盆栽试验,研究不同栽培基质条件下,基质的养分特征及其对牛大力根系生长和膨大状况的影响。结果表明:由草炭+泥土(体积比2∶1)及草炭+椰糠+砂(体积比1∶2∶1)混合的基质p H值较适中,有机质含量与氮磷钾养分含量均较高,养分状况较理想,牛大力根系发达,但膨大块根较少;而泥土与砂混合基质各项指标均比较低,养分比较贫乏,牛大力根系发达,但块根膨大明显。在本研究条件下,基质养分不是根系膨大的关键因素,泥土含量高的基质可能因为较为理想的通气和热量条件而有利于块根的膨大。     

观赏植物大岩桐(Sinningia speciosa)组织培养体系的建立和优化

实验探索了热带观赏植物大岩桐离体快繁的有效途径,以大岩桐叶片作为外植体,建立再生体系.各阶段的最佳培养基配比结果如下:初代培养基:MS+6-BA 1.0 mg/L+NAA 0.5 mg/L;增殖培养基:MS+6-BA 1.0 mg/L + NAA 0.05 mg/L;壮苗培养基:MS+6-BA 1.0 mg/L+NAA 0.8 mg/L;生根培养基:1/2MS,得到的组培苗经炼苗移栽后成活率高达100;.该体系的建立为其规模化生产及遗传改良提供了前提条件.     

Alley cropping Sesbania sesban (L) Merill with food crops in the highland region of Rwanda

Food production in the densely populated Rwandan highlands is impeded by soil erosion and loss in fertility. Alley cropping leguminous shrubs with food crops on contours is purported to minimize the problem and to provide wood and forage. This study reports the effect of Sesbania prunings plus moderate levels of N and P on bean (Phaseolus sp) and maize (Zea mays) yields in alley cropping. Experimental design was a randomized complete block with split-split plots. Main plots were alley width: 2, 4, 6 and 8 m. Phosphorus (P) at 0, 30 and 60 kg P₂O₅/ha occupied the subplot and nitrogen (N) at 0, 30 and 60 kg/ha were assigned at the sub-sub plot level. No P was applied to maize during the second cropping season. Crop yield in kg/ha included the land space taken by hedgerows. Bean yield in 6 m alleys (1100 kg/ha) was about twice that in 2 m alleys (500 kg/ha). Bean responded to N and P. Optimum alley width and N for bean yield were 6 m and 30 kg/ha, respectively. Cuttings from alley hedgerows provided stakes for climbing beans. Maize responded to N but not to residual P. The highest maize yield came from 8 m alleys with 40 kg/ha, but yields from 8 and 6 m alleys with the same N treatment were not significantly different. Maize plants in middle rows were significantly taller than plants in rows adjacent to hedgerows. Maize rust development showed significant alley width and row position effect. There were significantly fewer uredinia in the Sebania alleys relative to the control plots without shrub hedgerows. Rust development on maize in middle rows was significantly greater than development in border rows.     

超临界CO2萃取大叶紫薇种子油及GC-MS分析

应用超临界CO2萃取技术,研究了大叶紫薇种子油的萃取工艺。考察了压力、温度、粒度、CO2流量对大叶紫薇种子油萃取率的影响。得到最佳萃取条件为:压力30Mpa、温度40℃、粒度40目和CO2流量12kg/h。利用GC-MS分析了大叶紫薇种子油组成成分,共分析出12种脂肪酸,其中亚油酸的含量达到74.57%,并且检测出支链脂肪酸和奇数碳脂肪酸。