UVB exposure does not accelerate rates of litter decomposition in a semi-arid riparian ecosystem

Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive effects of UVB exposure and litter quality on decomposition in a Tamarix-invaded riparian ecosystem during the establishment of an insect biological control agent in northern Nevada. Feeding by the northern tamarisk beetle (Diorhabda carinulata) on Tamarix spp. trees leads to altered leaf litter quality and increased exposure to solar UVB radiation from canopy opening. In addition, we examined the dynamics of litter decomposition of the invasive exotic Lepidium latifolium, because it is well-situated to invade beetle-infested Tamarix sites. Three leaf litter types (natural Tamarix, beetle-affected Tamarix, and L. latifolium) differing in substrate quality were decomposed in litterbags for one year in the field. Litterbags were subjected to one of three treatments: (1) Ambient UVB or (2) Reduced UVB (where UVB was manipulated by using clear plastic films that transmit or block UVB), and (3) No Cover (a control used to test for the effect of using the plastic films, i.e. a cover effect). Results showed a large cover effect on rates of decomposition and nutrient release, and our findings suggested that frequent cycles of freeze-thaw, and possibly rainfall intensity, influenced decomposition at this site. Contrary to our expectations, greater UVB exposure did not result in faster rates of decomposition. Greater UVB exposure resulted in decreased rates of decomposition and P release for the lower quality litter and no change in rates of decomposition and nutrient release for the two higher quality litter types, possibly due to a negative effect of UVB on soil microbes. Among litter types, rates of decomposition and net release of N and P followed this ranking: L. latifolium > beetle-affected Tamarix > natural Tamarix. Altered nutrient dynamics with beetle introduction as well as the rapid decomposition rates exhibited by L. latifolium are consistent with vulnerability to secondary invasion. In this desert ecosystem, decomposition and nutrient release were strongly affected by litter type and much less so by UVB exposure.     

不同密度与施肥水平对玛咖产量的影响

在海拔2730 m的云南丽江金安乡进行种植密度、纯氮用量、纯磷用量和纯钾用量4个因素的正交试验,研究不同密度和施肥水平对玛咖产量的影响。结果表明,磷肥用量和种植密度对玛咖的产量有极显著影响,而氮肥用量和钾肥用量对玛咖的影响不明显。玛咖产量较高的是第5组合和第7组合,两者差异不显著,两组合的共同点是施用的纯磷量均达600 kg/hm2。该研究结果可为玛咖的大田生产提供参考。     

粘液繁殖体植物抱茎独行菜TTG1基因转化拟南芥的表型研究

[目的]将过量表达典型粘液繁殖体植物抱茎独行菜TTG1基因(LpTTG1)的转基因拟南芥株系表型与野生型和突变体进行比较,为深入研究LpTTG1基因的功能提供参考依据.[方法]在体视显微镜下,通过对拟南芥野生型、ttg1突变体及LpTTG1基因过表达转基因株系的植株表型,幼苗叶表皮毛、下胚轴和根毛以及种子形态进行观察比较.[结果]拟南芥ttg1突变体与野生型和LpTTG1过表达转基因型的幼苗在下胚轴的颜色、根毛着生方式、真叶表皮毛等方面有显著差异,但后两者表型间无显著差异.[结论]缺失TTG1基因可导致拟南芥幼苗形态发生显著变化,但此基因过量表达不一定对拟南芥形态产生影响.     

宽叶独行菜组培体系的建立和初步优化

以宽叶独行菜(Lepidium latifolium L.)的叶片和茎段为外植体,接种于MS培养基上进行愈伤诱导和植株再生培养,研究不同浓度激素对愈伤和再生苗生长状况的影响。结果表明,当激素浓度为1.5 mg/L2,4-D+1.0 mg/L IAA+0.5 mg/L 6-BA时,再生植株长势最好;当激素浓度为0.5 mg/L 2,4-D+1.0 mg/L IAA+1.5 mg/L 6-BA时愈伤组织长势最好;适当增加6-BA的浓度,可以促进再生植株根系的生长。     

独行菜属植物的研究进展

对独行菜属植物的资源研究与利用情况进行了总体概述,重点总结独行菜属植物化学成分与耐逆生理生化机制研究的进展,并提出了今后一段时间对独行菜属植物资源研究与利用的思考。     

低海拔引种栽培玛咖主要有效成分分析

为给低海拔地区栽培玛咖的开发和推广提供参考依据,以引种栽培基地湖南省湘西自治州不同海拔样地的玛咖为材料,采用醇浸取法和高效液相色谱法,对其生物碱、玛咖酰胺和玛咖烯等主要有效成分进行了测定与分析。测定结果表明:其总生物碱含量为0.707%~2.376%;玛咖酰胺含量为0.083 8%~0.529 2%,玛咖烯含量为0.008 3%~0.070 6%,玛咖酰胺+玛咖烯含量为0.099 7%~0.537 6%。分析结果表明:湘西低海拔地区栽培的玛咖其主要有效成分含量与秘鲁原产地的相当,说明海拔高度对玛咖有效成分含量无显著影响。文中因此认为,玛咖可以在低海拔地区大量推广栽培。     

不同产地玛咖挥发油成分的GC-MS分析

为探明玛咖的鉴别方法与质量评价体系,对丽江产玛咖干粉产品与秘鲁玛咖干粉产品采用水蒸馏溶剂萃取得挥发油,用气-质(GC-MS)联用技术法进行分析测定,鉴定其组成成分。结果表明:丽江玛咖的挥发油含量(≥0.407%)约是秘鲁玛咖(≥0.107%)的4倍;2种样品的挥发油成分以异硫氰酸苄酯(benzyl isothiocyanates)、苯乙腈(benzyl nitrile)及4-甲氧基苄基硫氰酸酯(4-Methoxybenzyl isothiocyanate)为主。丽江玛咖中异硫氰酸苄酯含量为75.35%,苯乙腈含量为14.56%,4-甲氧基苄基硫氰酸酯含量为7.38%;秘鲁玛咖中苯乙腈含量为85.20%、异硫氰酸苄酯含量为7.24%、4-甲氧基苄基硫氰酸酯含量为0.36%。丽江玛咖品质优良,气质联用技术可用于引种玛咖的鉴别及品质分析。     

独行菜属药学研究概况

在广泛文献检索基础上,对独行菜属植物的种类、成分、药理及临床应用进行了概述,为深入开发利用提供参考。     

玛咖秋葵咀嚼片直接压片工艺的优化

以黄秋葵超微粉作为压片辅料,优选玛咖秋葵咀嚼片的最佳工艺参数。采用粉末直接压片法加工玛咖秋葵咀嚼片产品,选取片重差异、崩解时限、硬度及脆碎度的综合评定值为评价指标,利用单因素试验研究充填压力、充填深度、转台速度和原料粒度对产品质量的影响,并通过响应面优化法确定最佳工艺。结果表明,玛咖秋葵咀嚼片产品的最佳工艺为充填压力31 kN、充填深度10 mm、转台速度25 r/min和原料粒度300目。本研究为进一步综合利用玛咖资源提供了科学依据,促进了玛咖产品的研发。     

云南栽培玛咖的营养成分分析与评价

对云南栽培的玛咖营养成分进行了分析,并与文献报道的秘鲁产玛咖进行了比较.结果表明:云南栽培玛咖含有16.7×104mg·kg-1的蛋白质、21.5×104·mg·kg-1粗纤维、9.30%氨基酸、多种无机元素、多种维生素等营养成分,脂肪含量低;所含营养成分的种类与秘鲁产玛咖类似,其中对人体有益的蛋白质、粗纤维、钙、铁、锌、VC等成分的含量较高,表明云南栽培玛咖的营养丰富,具有开发利用价值.