年桔采后带叶保鲜的研究

本试验证明采用1号复合保鲜剂能使年桔[Gitrus reticulata var.(langerina)Tan.]有效地带叶保鲜,桔红叶绿,更能满足春节期间送礼、观赏和食用的需要,即使落叶后也能延长贮存期。经四年较大批量的保鲜运输、贮存和试销获得好评。利用示踪原子法研究结果表明,年桔带叶保鲜的关键因子是外源激素和水分的作用。     

施硼对花生利用氮素的影响

用~(15)N 示踪技术研究施硼对砂地花生氮素吸收的影响。试验结果表明,在含硼量很低的细质砂土上,施硼促进花生的生长发育、提高荚果产量;促进花生对氮素的吸收、提高氮肥利用率;施硼促进根瘤生长发育、提高固氮能力。收获期土壤中残留肥料氮主要以有机态氰为主,且分布于0～20cm 土层中。     

基于NO_2~-显色反应的抗湿性喷雾雾滴密度和大小的检测体系

喷雾质量在一定程度上影响着"农药有效利用率"。喷雾雾滴密度和大小是影响喷雾质量的2个重要参数。针对目前应用最多的喷雾雾滴测量方法——水敏纸法,水敏纸存在抗湿性能差的缺点,该研究在保证原有使用性能的同时,设计制作一种适合在潮湿环境中使用的喷雾雾滴密度和大小的检测体系。该检测体系由检测卡和检测液两部分组成。检测液中含有能与检测卡反应的NO2-,综合考虑安全性和检测卡使用性能,检测液中Na NO2浓度应尽量接近但不能超过150 mg/L,该文下述试验采用Na NO2质量浓度125 mg/L。研究对检测卡的扩散均匀性和不同卡之间的平行性进行了探究,结果显示在同一检测卡上的相对标准偏差小于等于5.37%,在随机3张检测卡之间的相对标准偏差小于等于12.66%,结果表明该检测卡的均匀性和平行性较好;雾滴实际直径与斑点直径的拟合方程对于该方法制作的检测卡检测雾滴大小时具有较好的通用性;并与市售水敏纸进行检测准确性比较,结果显示在3种不同喷雾压力下,该检测卡检测结果与水敏纸基本相同,且与市售水敏纸同时进行抗湿性检验,结果显示本检测系统的检测卡具有较好的抗湿性能。因此,该文设计的喷雾雾滴密度和大小的检测体系在干燥与潮湿环境中均能良好使用。     

Using micromorphology to understand the rewetting mechanisms in milled peat

Milled peat, an important energy resource in Ireland, is produced by scarifying the surface of a peat bog and allowing the resultant particulate material to air dry prior to storage in large stockpiles on the peat bogs. The storage period can vary from 6 months to several years, during which time the stockpiles are subject to atmospheric precipitation which causes rewetting and a subsequent reduction in calorific and monetary value. A study was undertaken to characterise the pore structure of stockpiles and identify relationships between structure and propensity to rewet. Recent research examining rewetting mechanisms in milled peat stockpiles has focused mainly on macroscale physical data. With respect to the importance of the structure of a porous medium for water movement and storage, a characterisation of the pore and particulate structure of milled peat in stockpile was conducted using micromorphological techniques. Samples with water contents up to 0.6 g g⁻¹ were impregnated in the field. Thin sections produced in days as opposed to months (no period of chemical dehydration was required) were used to quantify macroporous structures using image analysis. Results illustrated that a significant hydraulic discontinuity existed between the surface and subsurface layers of stockpiles, a factor not identified by laboratory physical analysis. This endorsed the current hypothesis in that the milled peats of different genetic origin had different pore architectures which had a significant effect on the active rewetting mechanisms. The visualisation of water flow pathways using dye tracers suggested that in addition to the wetting front water movement, by-pass flow was an active rewetting mechanism.     

H2 15O translocation in rice was enhanced by 10 μm 5-aminolevulinic acid as monitored by positron emitting tracer imaging system (PETIS)

5-Aminolevulinic acid (ALA) acts to increase chlorophyll biosynthesis, photosynthesis, cold stress tolerance, and salt tolerance at low concentrations. We studied the effects of ALA on H₂ ¹⁵O translocation from the roots to the shoots of rice plants (Oryza sativa L. cv. Nipponbare) in real time by a positron-emitting tracer imaging system (PETIS). When the plant was treated with 10 μm ALA, the velocity of the H₂ ¹⁵O translocation from 2 to 12 min after absorption increased to 126, 137, 140% that of the control at 1.5, 2.5, and 3.5 h after ALA treatment, respectively. However, ALA did not affect the H₂ ¹⁵O translocation within 0.5 h of treatment. When the plant was treated with 0.1 mM ABA at 4 h after 10 μm ALA treatment, the velocity of the H₂ ¹⁵O translocation decreased at 0.5 h after ABA treatment. Those observations suggested ALA might be absorbed and transported to the guard cells within 1.5 h and functioned to expand the stomatal aperture.     

15N示踪法研究弱光对不同穗型冬小麦氮素积累和转运的影响

在大田试验条件下,采用15N示踪法,设置不遮光(T0)、开花后1～10d遮光(T1)、开花后11～20 d遮光(T2)和开花后21～30 d遮光(T3)4个处理,每个处理设置15N尿素作底肥+普通尿素作追肥和普通尿素作底肥+ 15N尿素作追肥两个15N示踪的微区,研究灌浆期弱光条件下不同穗型小麦品种对不同来源氮素的吸收、分配、转运和氮素利用效率的影响.结果表明,灌浆期不同阶段遮光均不利于植株对氮素的吸收、积累和转运,品种间表现一致,呈T0 ＞T3 ＞T2 ＞T1规律;小麦植株吸收的氮素68.0 ％～71.39％来自土壤氮,对追施氮的吸收量大于底施氮,灌浆期遮光增加了土壤氮素在营养器官的分配比例,不利于营养器官中土壤氮素向籽粒中的转运;各处理籽粒产量、肥料氮吸收量、氮肥利用率和肥料偏生产力均表现为T0 ＞T3＞ T2 ＞T1.相同处理条件下,济麦22籽粒产量和对肥料的利用大于山农8355.小麦灌浆期阶段性遮光降低了植株对氮素的吸收、转运和籽粒产量,以灌浆前期遮光影响最大,中期次之,后期最小;相同遮光条件下济麦22的籽粒产量和氮素利用率较高.     

Time-lagged induction of N2O emission and its trade-off with NO emission from a nitrogen fertilized Andisol

Abstract

To understand the influence of basal application of N fertilizer on nitrification potential and N₂O and NO emissions, four soil samples were collected from an upland Andisol field just before (sample 1) and 4 (sample 2), 36 (sample 3) and 72 (sample 4) days after the basal application of N fertilizer during the Chinese cabbage growing season from 12 September to 30 November 2005. The potentials of N₂O production and nitrification of the soils were determined using a ¹⁵N tracer technique and the soils were incubated for 25 days at 25°C and 60% water-filled pore space (WFPS). The results revealed that as much as 84–97% N₂O and almost all NO were produced by nitrification. The ¹⁵N₂O emission peak occurred approximately 350 h after the beginning of incubation for samples 1 and 2, but just 48 h later in samples 3 and 4. Total ¹⁵N₂O emission during the 25-day incubation of samples 3 and 4 ranged from 190 to 198 µg N kg^?1 soil, which was significantly higher than the 99–108 µg N kg^?1 soil recorded in samples 1 and 2. Basal application of N fertilizer did not immediately increase the nitrification potential and the ratio of N₂O to N added, but did dramatically increase the nitrification potential and the ratio of N₂O to N added as (¹⁵NH₄)₂SO₄ 36–72 days after the basal N fertilizer was added. In contrast, NO emission was negatively correlated with nitrification potential and total N₂O emission. As a result, a trade-off relationship between total NO and N₂O emissions was identified. The results indicated that there was a time-lagged induction of the change of N turnover in the soil, which was possibly caused by slow population growth of the nitrifiers and/or a slow shift in the microbial community in the soil.     

矿山排泥库渗漏特性的地下水示踪试验研究

以广西省某排泥库为研究区,对该排泥库进行地下水示踪试验,绘制时间浓度曲线,并利用一维水动力弥散模型对试验曲线进行了研究,计算出接收点地下水的流速、弥散系数和弥散度,探讨了示踪试验中出现多峰、双峰现象的机理。试验结果表明,地下水示踪模型计算所得流速与视流速总体接近,对示踪剂投放点和接收点的渗漏途径、地下水的流向、水力联系等情况的分析与实际情况吻合,该方法可以为库外水源污染情况评价和施工提供技术参考。     

荧光偏振免疫分析检测粮食及其制品中的真菌毒素研究进展

及时、快速和准确地检测粮食中真菌毒素的污染,从而对其进行严格、科学的控制和处理是保障中国粮食安全和人民身体健康的重要途径。基于特异性分子识别的均相荧光偏振免疫分析技术（Fluorescence Polarization Immunoassay,FPIA）兼具高通量、高速度、高灵敏和易于实现自动化等优点,特别适用于大批量粮食样本的快速筛选。文章综述了近10年来荧光偏振免疫分析检测粮食中真菌毒素的研究进展,并着重讨论了荧光偏振免疫分析的发展方向。     

用Cs-137示踪法研究浙江天台县典型坡面的土壤侵蚀规律

Cs-137示踪法具有简单、快速、准确的优点,已广泛应用于土壤侵蚀研究.本文在非耕地土壤侵蚀模型的基础上,在浙江省天台县典型区域内,得出Cs-137基准值为2382.02 Bq/m2,土壤Cs-137剖面分布函数为 Cs = 243.73e-0.113z,同时分析了非耕地典型坡面上不同部位的侵蚀与沉积规律.结果表明:土壤侵蚀主要发生在土壤表层20 cm以内的范围,坡地土壤净流失上部大于中下部,在距坡脚附近有土壤沉积现象.坡面不同部位的土壤侵蚀速率并不随着坡长的增加而简单地增大,而是随地表植被结构和覆盖度的不同而变化.