Fate of nitrogen derived from 15N-labeled plant residues and composts in rice-planted paddy soil

Pot experiments that lasted for 3 y were conducted to investigate the dynamics of nitrogen derived from plant residues (rice root, hull, straw, corn root, and rapeseed pod-wall), and composts (rice straw compost, cattle manure compost, and cattle manure sawdust compost), which were labeled with ¹⁵N. The rates of nitrogen uptake by rice (=N efficiency), denitrification, and immobilization derived from the organic materials incorporated before the first year of cultivation were investigated throughout 3 y of cultivation. At the end of the first year of cultivation, relatively high rates of N efficiency were obtained for rapeseed pod-wall (24.6%), rice straw (19.1%), and rice hull (18.6%), while corn root and cattle manure sawdust compost displayed a noticeably high denitrification rate. Corn root, cattle manure sawdust compost, rice hull, and rapeseed pod-wall exhibited remarkably high N mineralization rates ranging from 60 to 75% of the organic materials N applied. Cumulative rates of N efficiencies from the organic materials applied before the first year of cultivation fitted well to a first-order kinetic model and their asymptotes were compared among the organic materials. The asymptotic rates of N efficiency tended to depend on the rates at the end of the first year of cultivation.     

NH3 Volatilization,N2O Emission and Microbial Biomass Turnover from 15N-Labeled Manure Under Laboratory Conditions

On irrigated agricultural soils from semi-arid and arid regions, ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission can be a considerable source of N losses. This study was designed to test the capture of ¹⁵N loss as NH₃ and N₂O from previous and recent manure application using a sandy, calcareous soil from Oman amended one or two times with ¹⁵N labeled manure to elucidate microbial turnover processes under laboratory conditions. The system allowed to detect ¹⁵N enrichments in evolved N₂O-N and NH₃-N of up to 17% and 9%, respectively, and total N, K₂SO₄ extractable N and microbial N pools from previous and recent ¹⁵N labeled manure applications of up to 7%, 8%, and 15%. One time manured soil had higher cumulative N₂O-N emissions (141 µg kg^?1) than repeatedly manured soil with 43 µg kg^?1 of which only 22% derived from recent manure application indicating a priming effect.     

小麦各生育期对土壤不同深度标记硝态氮的利用

 在人为控制灌水的条件下，采用将15N标记到不同土壤层次的土柱试验，研究小麦不同生育期对土壤不同深度硝态氮的利用。结果表明，拔节、孕穗、扬花、成熟4个生育时期，小麦对不同深度标记硝态氮的吸收量及利用率均随深度增加而降低，拔节期对10～20、40～50和70～80 cm深度标记硝态氮的利用率分别为15.7%、3.4%和1.2%，孕穗期对3个标记深度硝态氮的利用率分别为30.6%、10.7%和3.9%，扬花期分别为33.1%、13.1%和5.1%，成熟期分别为32.5%、12.4%和4.7%；小麦对10～20 cm深度标记15N的吸收利用在孕穗期基本接近最高值，40～50、70～80 cm中下层标记硝态氮吸收峰值出现较10～20 cm标记处理推迟，至扬花期达最高值；不同层次土壤标记硝态氮的利用率与相应土层的根长密度和根干重呈显著的正相关关系。     

15N示踪研究烤烟对氮的吸收及分配

采用盆栽试验，利用^15N示踪研究了烤烟对不同形态氮的吸收利用规律。结果表明，烤烟各部位叶片对氮素的积累量表现为中部叶〉上部叶〉下部叶；肥料氮进入的比例具有下部叶〉中部叶〉上部叶的规律。不同生育期肥料氮进入烟叶中的比例，以团棵期最高，之后肥料氮进入的比例减少，统计分析结果表明（5％水平），从现蕾期到成熟期之间差异不大。同位素^15N标记肥料施入土壤后约39％～53％被烟株吸收利用，约22％～41％损失，约20％～37％残留于土壤中。     

饲料中C3植物含量对牛组织中稳定同位素碳、氮组成的影向

研究了饲料中C3植物含量不同时对牛不同组织中稳定性同位素碳、氮组成的影响。18头12~14月龄的青年牛随机分为6组,分别饲喂C3植物含量为50.0%、60.0%、70.0%、80.0%、90.0%、100.0%的饲料,132 d后屠宰。利用同位素比值质谱仪测定了牛尾毛、脱脂牛肉、粗脂肪、各种饲料的δ13C和δ15N值。结果表明,牛组织中碳同位素主要受饲料的影响,牛尾毛、脱脂肌肉、粗脂肪中的δ13C值随着C3植物含量在牛饲料中的比例增大而降低,并且均与C3植物含量呈极显著的负相关关系,用牛组织中的δ13C值可以预测饲料中C3植物所占的比例。牛组织中的氮同位素一定程度上受饲料因素的影响,但未随C3植物含量呈现规律性变化。牛不同组织中δ13C和δ15N与饲料之间的富集或贫化比例与其他报道并不一致。     

Compartmentalization of the soil animal food web as indicated by dual analysis of stable isotope ratios (N/N and C/C)

The soil animal food web has become a focus of recent ecological research but trophic relationships still remain enigmatic for many taxa. Analysis of stable isotope ratios of N and C provides a powerful tool for disentangling food web structure. In this study, animals, roots, soil and litter material from a temperate deciduous forest were analysed. The combined measurement of δ¹⁵N and δ¹³C provided insights into the compartmentalization of the soil animal food web. Leaf litter feeders were separated from animals relying mainly on recent belowground carbon resources and from animals feeding on older carbon. The trophic pathway of leaf litter-feeding species appears to be a dead end, presumably because leaf litter feeders (mainly diplopods and oribatid mites) are unavailable to predators due to large size and/or strong sclerotization. Endogeic earthworms that rely on older carbon also appear to exist in predator-free space. The data suggest that the largest trophic compartment constitutes of ectomycorrhizal feeders and their predators. Additionally, there is a smaller trophic compartment consisting of predators likely feeding on enchytraeids and potentially nematodes.     

鸡p15INK4B基因的克隆表达及纯化

为研究鸡p15INK4B蛋白的功能及为制备此蛋白的单克隆抗体提供材料,应用引物搭桥法合成p15INK4B基因,应用基因工程的手段构建p15INK4B基因的原核表达载体,在E.coliRosetta(DE3)菌进行融合表达,并对表达产物进行亲和层析纯化。结果成功地构建了p15INK4B基因原核表达载体,经亲和层析制备了较高纯度的目的表达产物。     

鲜食马铃薯新品种天薯15号的选育

天薯15号是以陇薯7号为母本,天薯9号为父本杂交选育而成的鲜食型马铃薯新品种。从播种至块茎成熟119 d(天)左右,属晚熟品种。薯块椭圆形,皮黄色,薯肉淡黄色,芽眼浅。单株结薯4.4个,平均单薯质量92.2 g,商品率89.8%。每667 m~2产量在1 500 kg以上,在甘肃的天水、陇南、临夏、定西、平凉等地均可种植。     

水稻光温敏两系不育系15S特征特性及繁殖技术

介绍了水稻光温敏两系不育系15S的形态特征和生育特性,提出了繁殖地点选择,生育期安排,培育壮秧,落地谷的处理等繁殖高产优质不育系种子的技术措施.     

R318的抗褐飞虱特性与育种利用

[目的]研究R318的抗褐飞虱特性与育种利用。[方法]以TN1、RHT、B5为对照,对R318及其衍生品系进行褐飞虱田间抗虫鉴定,用抗性基因Bph15引物MS5对R318及其衍生品系进行分子检测。[结果]田间鉴定R318对褐飞虱表现为抗,其衍生品系表现为中抗-感虫;分子检测R318及其衍生品系与B5具有一致的带型。[结论]R318含有的抗性基因可能是Bph15。