棉铃发育过程中不同组织IAA含量变化特点

为了解IAA与棉纤维品质形成间的关系及棉铃各部位IAA积累转运特点,本研究分析了棉铃各部分在发育过程中IAA含量的变化特点。通过选择陆地棉标准系TM-1、长纤维种质‘母35’和短纤维种质‘208’3个纤维长度差异较大的陆地棉材料,利用酶联免疫法对浙江杭州、海南三亚两地田间试验的各材料不同发育阶段的棉仁、棉籽壳、棉纤维、棉铃壳进行了IAA含量的测定。结果表明,不同参试材料的棉仁IAA含量存在明显差异,棉籽壳、棉纤维与棉铃壳的IAA含量峰值出现时间晚于棉仁,棉铃各个组织IAA含量具有随棉铃组织从内向外逐渐降低的趋势。研究表明,IAA可能是棉纤维发育的正效应因子,且棉铃发育过程中IAA可能呈初期在棉仁富集、随发育进程沿棉铃组织由内向外运输的规律。     

谷子秸秆剪切力与其饲料营养特性变化规律及相互关系

为探究谷子秸秆力学性质与其饲料特性的变化规律及相互关系，选用谷物完熟期的谷子秸秆，将其分为5段（近根部、中下部、中部、中上部、上部）并每隔7 d进行秸秆节间、茎节力学性质（剪切、压缩）和饲料特性（形态指标、营养成分）测定。试验结果表明：谷物完熟后，随着时间的推进，秸秆节间、茎节剪切力、抗压强度、干物质含量、纤维素含量、半纤维素含量和木质素含量总体上呈增大趋势，而秸秆含水率、当量直径、横截面积、线性密度和粗蛋白含量总体上呈减小趋势。谷子秸秆单位直径剪切力与含水率和线性密度呈负相关关系（R2≥0.903），与其干物质、纤维素、半纤维素和木质素含量呈正相关关系（R2≥0.845），与其粗蛋白含量无显著相关关系（P>0.05）。采收期内，谷子秸秆基部起秸秆剪切力至顶部逐渐增大，且剪切力与当量直径、横截面积呈正相关关系（R2≥0.916）。试验表明谷子秸秆饲料特性指标验证试验值与预测值相对误差不大于6.48%，预测模型合理。测量秸秆剪切力可用于预测其形态指标参数和营养成分含量，进而一定程度地反映秸秆饲用价值和反刍动物择食趋向。采收期内，谷子中部及以上秸秆单位直径剪切力显著小于其近根部（P<0.05），更适合饲用；且谷物完熟后，及时采收可避免秸秆饲用价值降低。该研究可为高效利用谷子秸秆资源提供参考。     

Decreasing of methanogenic activity in paddy fields via lowering ponding water temperature: A modeling investigation

Methane (CH₄) is a potent greenhouse gas and the huge CH₄ fluxes emitted from paddy fields can prejudice the eco-compatibility of rice cultivation. CH₄ production in submerged rice crops is known to be highly influenced by water temperature. Hence, lowering ponding water temperature (LPWT) could be an option to mitigate CH₄ emissions from paddy environments when it is possible either to irrigate with slightly colder water or to increase ponding water depth. However, paddy soil is a complex environment in which many processes are simultaneously influenced by temperature, leading to a difficult prediction of LPWT effects. For this reason, LPWT efficiency is here theoretically investigated with a one-dimensional process-based model that simulates the vertical and temporal dynamics of water temperature in soil and the fate of chemical compounds that influence CH₄ emissions. The model is validated with literature measured data of CH₄ emissions from a paddy field under time-variable temperature regime. Based on modeling results, LPWT appears promising since the simulated reduction of CH₄ emissions reaches about −12% and −49% for an LPWT equal to −5 °C during the ripening stage only (last 30 days of growing season, when rice is less sensitive to temperature variations) and −2 °C over the whole growing season, respectively. LPWT affects CH₄ emissions either directly (decreasing methanogenic activity), indirectly (decreasing activity of bacteria using alternative electron acceptors), or both. The encouraging results provide the theoretical ground for further laboratory and field studies aimed to investigate the LPWT feasibility in paddy environments.     

Influences of population density,temperature and latitude on the growth of invasive topmouth gudgeon Pseudorasbora parva

Plasticity in life‐history traits provides advantages for introduced fish in overcoming demographic bottlenecks that would otherwise inhibit establishment. Here, the influence of population density, temperature and latitude was tested on the growth increments and growth rates of invasive populations of topmouth gudgeon Pseudorasbora parva, a small Asian cyprinid fish that is invasive across Europe. Aquaria experiments tested the roles of fish number and temperature on growth increments under a fixed food supply, pond experiments tested the role of density on growth increments, and a field study completed in England and Wales tested the influence of density and latitude on growth rates. In aquaria experiments, whilst growth increments were higher at 21 and 23 °C than at 19 and 25 °C, fish number had a greater influence on growth than temperature. Higher growth increments were produced at lower densities. In experimental ponds, growth increments were significantly higher in ponds with low densities of P. parva compared with those at elevated densities. In the field study comprising 10 wild populations across a latitudinal gradient of 4.0°N, a difference in mean air temperatures of approximately 3 °C, and estimated densities between 0.5 and 65.0 m^?2, population density was the only significant predictor of growth rates. Whilst populations at very low densities comprised of significantly faster growing individuals, there were no significant differences when densities were between 15 and 65 m^?2. Thus, invasive P. parva populations have considerable growth plasticity, especially at low densities, with this likely to be important in their ability to colonise new environments.     

对我国LULUCF碳计量监测方法的探讨

围绕我国林业编制温室气体清单这一重要工作,介绍了IPCC关于LULUCF温室气体清单编制系列技术指南的技术要点和要求,阐明了我国林业温室气体清单编制工作的进展,提出了林业开展LULUCF碳监测工作未来面临的需求。同时,在分析美国、欧盟、加拿大等发达国家LULUCF温室气体清单编制做法和经验的基础上,提出了"在森林资源清查样地系统上构建"、"新布设LULUCF大样地系统"等2种开展LULUCF碳监测的思路,目的是为推动我国林业LULUCF碳监测达到国际先进水平提供建议。     

当代大学生思想变化规律的研究——基于蚌埠学院部分学生的问卷调查与访谈

对当代大学生进行思想政治理论教育，必须深入研究当代大学生的思想变化规律。研究表明，当代大学生的思想变化呈现出如下规律：马克思主义为主流信仰，信仰比例随年级升高呈“V”形分布；政治认同感强，政治关注度与自身利益紧密相关；人生态度积极乐观，注意自我价值的实现；反对非诚信行为，期待诚信的社会环境。对以上规律的研究，有助于更有效地对当代大学生开展社会主义核心价值观教育。     

基于SWAT模型的大安市降水入渗量变化的模拟研究

针对近年的研究热点,通过SWAT模型对半干旱、盐碱化严重的吉林省大安市进行降水入渗模拟。以2000、2004和2008年遥感影像解译得到的土地利用数据为基础,结合SWAT模型的模拟结果,讨论LUCC与降水入渗量的相关关系。2008年与2000年相比,难利用地的面积有所降低,旱地、草地等发生了大面积的增加,研究区内土地状况有所好转。通过SWAT模型运行得到的结果显示:2008年的平均降水入渗量为56.27 mm,比2000年的值高。利用降水入渗系数法进行计算,也得到了2008年的降水入渗量高于2000年的结果,这与SWAT模型模拟得到的结果有着相同的趋势,且平均降水入渗量的标准偏差为5.27,说明SWAT模型对于研究区有良好的适应性。同时,根据土地利用数据和SWAT模型模拟数据可以得知,LUCC对研究区的降水入渗量存在着一定的相关性。     

Can additional N fertiliser ameliorate the elevated CO2‐induced depression in grain and tissue N concentrations of wheat on a high soil N background?

Elevated CO₂ stimulates crop yields but leads to lower tissue and grain nitrogen concentrations [N], raising concerns about grain quality in cereals. To test whether N fertiliser application above optimum growth requirements can alleviate the decline in tissue [N], wheat was grown in a Free Air CO₂ Enrichment facility in a low‐rainfall cropping system on high soil N. Crops were grown with and without addition of 50–60 kg N/ha in 12 growing environments created by supplemental irrigation and two sowing dates over 3 years. Elevated CO₂ increased yield and biomass (on average by 25%) and decreased biomass [N] (3%–9%) and grain [N] (5%). Nitrogen uptake was greater (20%) in crops grown under elevated CO₂. Additional N supply had no effect on yield and biomass, confirming high soil N. Small increases in [N] with N addition were insufficient to offset declines in grain [N] under elevated CO₂. Instead, N application increased the [N] in straw and decreased N harvest index. The results suggest that conventional addition of N does not mitigate grain [N] depression under elevated CO₂, and lend support to hypotheses that link decreases in crop [N] with biochemical limitations rather than N supply.     

Soil enzyme activities during the 2011 Texas record drought/heat wave and implications to biogeochemical cycling and organic matter dynamics

Extreme droughts and heat waves due to climate change may have permanent consequences on soil quality and functioning in agroecosystems. During November 2010 to August 2011, the Southern High Plains (SHP) region of Texas, U.S., a large cotton producing area, received only 39.6 mm of precipitation (vs. the historical avg. of 373 mm) and experienced the hottest summer since record keeping began in 1911. Several enzyme activities (EAs) important in biogeochemical cycling were evaluated in two soils (a loam and a sandy loam at 0–10 cm) with a management history of monoculture (continuous cotton) or rotation (cotton and sorghum or millet). Samplings occurred under the most extreme drought and heat conditions (July 2011), after precipitation resulted in a reduction in a drought severity index (March 2012), and 12 months after the initial sampling (July 2012; loam only). Eight out of ten EAs, were significantly higher in July 2011 compared to March 2012 for some combinations of soil type and management history. Among these eight EAs, enzymes key to C (β-glucosidase, β-glucosaminidase) and P cycling (phosphodiesterase, acid and alkaline phosphatases) were significantly higher (19–79%) in July 2011 than in March 2012 for both management histories regardless of the soil type (P > 0.05). When comparing all sampling times, the activities of alkaline phosphatase, aspartase and urease (rotation only) showed this trend: July 2011 > March 2012 > July 2012. Activities of phosphodiesterase, acid phosphatase, α-galactosidase, β-glucosidase and β-glucosaminidase were higher in July 2011 than July 2012 in at least one of the two management histories. Total C was reduced significantly from July 2011 to March 2012 in the rotation for both soils. Only the activities of arylsulfatase (avg. 36%) and asparaginase showed an increase from July 2011 to March 2012 for both soil types, which may indicate they have a different origin/location than the other enzymes. EAs continued to be a fingerprint of the soil management history (i.e., higher EAs in the rotation than in monoculture) during the drought/heat wave. This study provided some of the first evidence of the adverse effects of a natural, extreme drought and heat wave on soil quality in agroecosystems as indicated by EAs involved in biogeochemical cycling.     

自然低温胁迫下3种桉树的叶绿素荧光特性研究

对临安市3种桉树幼苗叶片叶绿素荧光特性进行研究,结果表明,自然低温下,各桉树表现出不同的适应性,总的来说,邓桉>柳桉>巨桉;自然低温(日最低气温-3.6℃)对柳桉和巨桉造成较大损害,而邓桉可通过维持相对较高的光化学效率,以及利用不断增加的qN来进行耗散,具有较强的抵抗低温胁迫伤害的能力。