林芝河谷地区典型农田土壤主要性质及重金属状况初探

选择西藏林芝河谷地区代表性麦田及蔬菜大棚土壤,对其主要土壤肥力指标、重金属浓度及相应小麦及蔬菜样的重金属浓度进行了测定。结果发现:该区耕地土壤有机质、全氮、碱解氮处于中等及较缺乏水平,全磷、全钾、有效锌处于缺乏水平,速效磷、钾及有效铜处于较丰富水平;研究区土壤及作物铜、锌、镉浓度均未超出我国土壤环境质量标准,但农业生产活动造成了表层土壤铜、锌、镉的富集。研究区耕地应注重有机肥、化肥及微量元素的合理施用,同时注意农业生产活动造成的土壤酸化、重金属富集问题并加以监控,以促进该区农业的可持续发展。     

典型自然带土壤氮磷化学计量空间分异特征及其驱动因素研究

植物生活型、地形及区域气候特征等对土壤养分的空间分布有着重要的影响。通过对我国典型自然带土壤氮磷化学计量与植物生活型、地形及气候因素间相互关系的研究,探讨了我国土壤氮磷的空间变异与分布特征及其主要控制因素。结果发现,5个自然带的土壤全氮(TN)和氮磷比(N/P)存在显著差异(p0.01);除温带荒漠带较低(0.47 mg g~(-1))外,土壤全磷(TP)均值总体变化不明显(p0.05)。在不同自然带区域内,TN、TP及N/P变化与海拔、温度及降水呈现出显著的线性和非线性二次相关,即表现出线性与单峰模式。暖温带落叶阔叶林带、温带草原带、温带荒漠带森林土壤中TN,以及青藏高原高寒植被带草本土壤中TP、温带荒漠带森林土壤的N/P主要受海拔因素的影响,而温带草原带草本植物的土壤TP则主要受降水的影响。同时,研究还发现,在多要素共同作用时,其影响程度也略有差异,温度和海拔作为控制因素影响亚热带常绿阔叶林带森林和温带草原带草本土壤TN变化,但前者受温度控制更为明显,后者则以海拔为主要驱动因素,而温带荒漠带草本土壤和森林土壤的TN主要受海拔和降水作用的影响,但以降水影响为主;亚热带常绿阔叶林带森林土壤TP,温带草原带、温带荒漠带和青藏高原高寒植被带草本土壤的N/P受植物生活型、地形及气候的共同影响,但程度略有不同,其中TP表现为降水温度海拔,而N/P为温度海拔降水。因此,在自然带和植物生活型的主控背景下,海拔、温度和降水的主控或交互作用直接驱动土壤氮磷及其化学计量特征的空间分异。     

Nitrogen effects on cantaloupes

Abstract

The NO₃ levels in cantaloupe (Cucumis melo L.) petioles relate closely to N treatment and reflect the N status of the cantaloupe plant. Suggested levels of petiole NO₃ in cantaloupes grown in Arizona are presented. Nitrogen treatment had little effect on melon size, earliness, or most storage quality factors that were evaluated except that deficiencies resulted in lower netting, poor general appearance and an increase in cull melons.     

利用组织培养技术提取甘草黄酮

本研究筛选了两种能快速诱导甘草疯长型愈伤组织的培养基MS5和MS7,用微波法提取甘草愈伤组织和野生甘草根中总黄酮。测定结果显示：三年生野生型胀果甘草根中总黄酮的含量约为6.02%,培养3~4周的胀果甘草愈伤组织中总黄酮的含量约为1.1%。结果表明：组织培养生产黄酮在生产效率、工厂化生产、避免季节限制、保护野生甘草资源及实际应用中更具优势。本研究可为从甘草中提取总黄酮提供一条可借鉴的途径。     

氮磷钾互作效应对甘草黄酮含量影响的初步研究

研究结果表明,宁夏红寺堡扬黄新灌区沙壤灰钙土氮、磷、钾对甘草总黄酮含量影响大小为:施磷(负效应)大于施氮(正效应)大于施钾(负效应);因子互作效应对甘草总黄酮含量影响大小顺序为P×K>N×P>N×K;红寺堡扬黄新灌区沙壤灰钙土人工栽培甘草总黄酮含量≥5.0%以上的农艺措施为:施纯N 119.6~138.8kghm-2、施纯P2O5153.2~178.5 kghm-2、施纯K2O 90.9~105.6 kghm-2。     

Species composition of arbuscular mycorrhizal fungi in two mountain meadows with differing management types and levels of plant biodiversity

Species composition of arbuscular mycorrhizal fungi (AMF) was analysed in two differently managed mountain grasslands in Thuringia (Germany). Arbuscular mycorrhizal fungi were studied in the roots of 18 dominant plant species from a total of 56 (32%). Additionally, spores of AMF were isolated from soil samples. Arbuscular mycorrhizal fungi species composition was analysed based on 96 sequences of the internal transcribed spacer of the nuclear ribosomal DNA, 72 originated from mycorrhizal roots, and 24 originated from AMF spores. Phylogenetic analyses revealed a total of 19 AMF species representing all genera of the Glomeromycota except Scutellospora and Pacispora. Despite a different farming intensity, resulting in remarkable differences concerning their plant species diversity (27 against 43 plant species), the diversity of AMF was found to be similar with 11 species on the intensively farmed meadow and ten species on the extensively farmed one. Nevertheless, species composition between both sites was clearly different. It thus seems likely that the AMF species composition, but not necessarily the species number, is related to above ground plant biodiversity in the system under study.     

Correlation between earthworms and plant litter decomposition in a tropical wet forest of Puerto Rico

Earthworms are recognized to play an important role in the decomposition of organic materials. To test the use of earthworms as an indicator of plant litter decomposition, we examined the abundance and biomass of earthworms in relation to plant litter decomposition in a tropical wet forest of Puerto Rico. We collected earthworms at 0–0.1 m and 0.1–0.25 m soil depths from upland and riparian sites that represent the natural variation in soils and decomposition rates within the forest. Earthworms were hand-sorted and weighed for both fresh and dry biomass. Earthworms were dominated by the exotic endogeic species Pontoscolex corethrurus Müller; they were more abundant, and had higher biomasses in the upland than in riparian sites of the forest. Plant leaf litter decomposed faster in the upland than riparian sites. We found that earthworm abundance in the upper 0.1 m of the soil profile positively correlated with decomposition rate of plant leaf litter. Ground litter removal had no effect on the abundance or biomass of endogeic earthworms. Our data suggest that earthworms can be used to predict decomposition rates of plant litter in the tropical wet forest, and that the decomposition of aboveground plant litter has little influence on the abundance and biomass of endogeic earthworms.     

大豆连作土壤肥力变化与有害生物发生的关系

1995—2003年采用定点定期采样系统调查与室内测定相结合的方法,针对连作大豆土壤营养含量、病虫基数与植株体营养,生物学性状、病虫草发生及产量品质的关系进行了研究,并对各相关性状间的关系进行了系统的统计分析,建立了数学模型,对指导大豆的高产优质栽培具有重要的意义。     

短花针茅群落主要物种种间关系的研究

应用2×2列联表的χ2检验和Spearman秩相关分析方法对短花针茅群落21个主要物种的种间关系进行了分析.结果表明:呈不显著相关的种对多于呈显著和极显著相关的种对,呈正相关和负相关的种对在所有种对中几乎各占一半;短花针茅群落21个主要物种可划分为三个生态种组,即冷蒿组、狭叶锦鸡儿组和短花针茅组;研究物种种间关系时,Spearman秩相关系数检验具有较高的灵敏度.     

地下管道震害评估方法研究

目前地下管道的震害预测评价方法大多需要管线本身的较为精细的力学参数,而在实际的城市管网震害评估工作中此类参数并不容易获取.为了简化地下管道震害评价方法,本文基于层次分析法和数理统计耦合算法,提出了一种简化的地下管道震害评估方法—管道破坏度指数法,将该方法应用于某城市的地下管道震害评估工作并对该市7度、8度、9度地震时的地下管道震害评估进行了分析,与应用传统方法对比显示计算结果基本一致,验证了本文方法的确实可行和有效性.由于本文方法只选取影响地下管道破坏的典型因素,不仅大大简化了数据收集的工作,增加了工作效率,同时也保证了实际操作的可行性.