龙眼光合作用对环境温度的响应和适应

在年生长期中测定了龙眼叶片光合作用对测度的影响,结果发现,龙眼光合作用最适温与最适温下的光饱和光合速率都有一定的季节变化,但季节变幅不大,不同季节的光合最适温在２２～２８℃之间,光合最适温与植株前５－１０天所处的环境平均气温密切相关,春秋季光合最适明显高于环境气温,夏季光合最适明显低于环境气温,光合最适温随光照强度的变化而变化,这些结果显示了龙眼光合作用对环境温度的特殊要求。     

Using remote sensing to predict outbreaks of Oestrus ovis in Namibia

The Directorate of Veterinary Services of the Ministry of Agriculture, Water and Rural Development of Namibia issues warnings to farmers in the south of the country about the likelihood of infestation of small-stock by the nasal bot fly, Oestrus ovis. Farmers can then treat their stock at the most appropriate time. The O. ovis puparia develop at shallow depths in the soil and the timing of emergence is directly dependent on climatic conditions, specifically the number of degree-days above a particular threshold soil temperature. Based on temperature measurements from only a few stations scattered throughout the country, the veterinary department warnings lack precision in space and time. This paper presents an attempt to support the programme of warnings with accumulated temperature information from Meteosat satellite images, in order to strengthen predictions of the time of emergence in specific places, and to improve the precision and reliability of warnings given to farmers.     

基于ZigBee无线网络的大棚种植温度监测系统

针对大棚种植温度监测系统,讨论了无线温度监测系统的技术要求,阐述了基于ZigBee无线检测网络的系统结构与硬件、软件设计。随着规模农业的快速发展,无线网络农业自动化系统将有非常广阔的推广应用前景。     

Comparing chamber and eddy covariance based net ecosystem CO2 exchange of fen soils

Due to their high emission potential, the reporting of CO₂ emissions from peatlands requires exact emission factors for different land use categories. Recently used emission factors are mainly based on CO₂ flux measurements by chamber techniques or the micrometeorological eddy covariance (EC) method. However, evidence about the reliability and comparability of annual CO₂ balances based on these methods is scarce. Therefore, manual chamber measurements of ecosystem respiration (R_ECO) and net ecosystem exchange (NEE) were conducted for two years (March 2012–April 2014) to model annual balances of two sites on fen soils with different land use intensity in northern Germany: an unutilized and rewetted grassland (UG) and an intensively utilized wet grassland (GW). Simultaneously, EC measurements of NEE were conducted on the sites. Two reasons for occasionally great deviations in NEE between the methods could be observed: (1) the accordance of both methods was most hampered during transition periods such as the beginning of the growing season and the onset of regrowth after a grassland defoliation due to different spatial scales of EC and chamber measurements and (2) R_ECO and gross primary production (GPP) partitioned from EC NEE measurements were systematically lower than those from the chamber‐based model, which could be a result of the EC energy balance gap. Differences were more pronounced for the managed site GW as a result of more frequent regrowth periods. It is concluded that the EC and chamber method can show comparable results for the CO₂ exchange of grasslands on fen soils when the limitations of both methods are known and considered for the reporting of emission factors. These limitations are due to energy balance closure and potentially biased footprints for EC and a restricted representativeness especially during early stages of plant development for the chamber method.     

浅谈低温热水地板采暖的特点及应用前景

低温热水地板采暖广泛应用于北欧、美国、加拿大以及韩国等国家，但在我国地板采暖的应用才刚刚起步。本文简要阐述了低温热水地板采暖的特点，并对其在我国的应用前景进行了展望。     

Pt100铂热电阻在雨花茶精揉机温度控制中的应用

从铂热电阻非平衡电桥测温原理出发,分析了雨花茶精揉机揉锅温度测量与控制系统在温度信号采集过程中引入的非线性误差,提出了以Pt100铂热电阻和AT89S52单片机为核心的软件非线性补偿方案,给出了系统硬件结构图和软件设计流程图。实验结果表明该方案简便有效,能够提高温度控制系统性能。     

不同培养基及温度对栎松口蘑菌丝生长的影响

栎松口蘑菌丝生长在17~22℃(室温~变温)、24℃26℃3个梯度之间差异不显著,培养基之间差异极显著,以Ⅴ号配方较为合适,而且培养基和温度之间有互作效应。     

Water transport in wood particle material

An analogy between water flux and the field of temperature gradient in a column of wood fuel chips was discovered by these experiments. The heat—mass transfer coefficient was determined by least squares method. An equation relating water flux and temperature gradient was developed and it was demonstrated that the temperature gradient was the main driving force for water transport. The mechanism was evaporation—condensation of water vapor through natural convection in air phase. The study gives a theoretical explanation for analyzing the problem of water transport in wood particle material.     

樟树幼树光合特性及其对CO2浓度和温度升高的响应

用Li COR 6 4 0 0便携式光合作用测定系统对亚热带常绿阔叶树种樟树幼树的光合特性及其对CO2 升高的响应进行了研究。结果表明 :樟树叶片光合速率日变化呈双峰曲线 ,最高峰出现在 10 :0 0 ,次高峰出现在 14 :0 0 ,午间有明显的“午休”现象 ,气孔因素是导致午休的主要原因。中午光照强度大 ,叶片与空气之间的水汽压差达到最大值 ,相对湿度、气孔导度、胞间CO2 浓度达到最小值 ,诱导叶片光合午休。正常大气条件下 ,樟树叶片光饱和点为 12 5 0 μmol·m- 2 s- 1 ,光补偿点 4 0 6 μmol·m- 2 s- 1 ,在 10 0 0 μmol·m- 2 s- 1 光强下CO2 饱和点为 12 0 0 μmol·mol- 1 ,CO2 补偿点为 5 0 μmol·mol- 1 。水分利用效率、气孔导度、蒸腾速率在不同的CO2 浓度梯度下 ,随着光强的增加而增加。在 2 4～ 35℃时 ,随着光合有效辐射的增加 ,温度升高导致樟树光合速率降低。     

One-day rate measurements for estimating net nitrification potential in humid forest soils

Measurements of net nitrification rates in forest soils have usually been performed by extended sample incubation (2–8 weeks), either in the field or in the lab. Because of disturbance effects, these measurements are only estimates of nitrification potential and shorter incubations may suffice. In three separate studies of northeastern USA forest soil surface horizons, we found that laboratory nitrification rates measured over 1 day related well to those measured over 4 weeks. Soil samples of Oa or A horizons were mixed by hand and the initial extraction of subsamples, using 2 mol L⁻¹ KCl, occurred in the field as soon as feasible after sampling. Soils were kept near field temperature and subsampled again the following day in the laboratory. Rates measured by this method were about three times higher than the 4-week rates. Variability in measured rates was similar over either incubation period. Because NO₃⁻ concentrations were usually quite low in the field, average rates from 10 research watersheds could be estimated with only a single, 1-day extraction. Methodological studies showed that the concentration of NH₄⁺ increased slowly during contact time with the KCl extractant and, thus, this contact time should be kept similar during the procedure. This method allows a large number of samples to be rapidly assessed.