CONTROLLED-RELEASE UREA FOR RICE PRODUCTION AND ITS ENVIRONMENTAL IMPLICATIONS

Controlled-release urea (CRU) and its placement method in rice production were investigated during 2007 and 2008 seasons. Controlled-release urea was applied at 62.5, 125, and 187.5 kg nitrogen (N) ha^?1, and the urea was 187.5 kg N ha^?1. All the CRU treatments were applied to the nursery beds once, and they were brought into the paddy field during transplanting, while the urea treatment was split into three applications from the plowing to the harvest. The results showed that rice seedlings with CRUs germinated and grow well and there was no salt damage at the nursery stage. The CRU treatment with 125 kg N ha^?1 had 33% less N than urea treatment (187.50 kg N ha^?1), but it produced significantly higher grain and straw yields, higher total N uptake and total apparent N uptake efficiency. In addition, all the CRU treatments effectively decreased floodwater ammonium (NH₄ ⁺)-N and nitrate (NO₃ ^?)-N concentrations, pH, and N runoff.     

基于激光三角法的地表粗糙度测试仪的研制

针对接触法测试地表粗糙度需要人工参与、测试时间长等问题,该文提供了一种快速的地表粗糙度测试的仪器及测试方法。基于激光三角原理,将激光投影到待测目标上,摄像机接收反射光的图像,通过图像处理算法及坐标转换得到被测区域的三维坐标,再根据粗糙度计算公式得到地表粗糙度参数的结果。将该仪器分别进行了精度及野外测试试验,精度试验测量结果的平均相对误差最大值为2.93%,仪器典型分辨率在垂直仪器扫描方向为0.78 mm,仪器扫描方向为1 mm,垂直大地方向为0.83 mm。试验结果表明,农田表面空间自相关系数的测量结果反映出了农田的垄结构特征,验证了该文仪器及方法的可行性及有效性。     

散发性结直肠癌遗传标识物研究进展

散发性结直肠癌（sporadic colorectal cancer,sCRC）是一类没有明显家族遗传倾向,由遗传因素和环境因素共同作用的消化道恶性肿瘤。近年来,分子技术的发展使发现复杂疾病潜在的生物标识物成为可能。基于全基因组关联研究（genome-wideassociationstudy,GWAS）以及高通量测序技术的应用,已经从全基因组范围内确定了大量肿瘤易感基因以及其后天突变标识物。本文对近年来散发性结直肠癌（sCRC）遗传标识物最新研究进展作一综述,并对其未来研究方向加以展望。     

稻田水肥资源高效利用与调控模拟

水和肥是影响作物产量与生态环境的重要因素。为揭示稻田水肥利用规律,以达到稻田节水、省肥、高产、减排的目标,该文以湖北省漳河团林实验站稻田水肥耦合灌溉与控制排水试验观测数据为基础,联合运用作物生长模型ORYZA 2000和田间水文模型DRAINMOD 6.0,模拟分析不同降水、节灌、施肥、控排条件下的水稻产量与稻田排水量响应关系,得出了稻田水肥调控的临界条件,即采用稻田间歇灌溉方式,灌水定额30 mm,施氮量170 kg/hm2左右,控制排水水位20 cm时,节水12.5%～18.87%、省肥35.1%、增产11%、减排19.9%。本研究对加强农田水肥科学管理,提高水氮生产效率,防治农业面源污染,促进灌区可持续发展具有重要意义。     

Effect of inoculation with AM fungi on lead uptake,translocation and stress alleviation of Zea mays L. seedlings planting in soil with increasing lead concentrations

In this work, a greenhouse experiment, arranged in a randomized block design 2 × 6 factorial with six replicates, was conducted to estimate the effect of inoculation with arbuscular mycorrhizal fungi (AMF) on lead uptake, location and stress attenuation in mycorrhizal Zea mays L. seedlings. Treatments were the mycorrhizal inoculation (+M) or non-mycorrhizal inoculation (?M) and six lead concentrations (0, 50, 100, 200, 500 and 1000 μg/g) to soil. The results showed that AM fungal inoculation could attenuate the oxidative stress of lead to Z. mays seedlings. The higher height, basal diameter and biomass of seedlings were found in mycorrhizal Z. mays seedlings growing in the soil with increasing lead concentrations. Moreover, superoxide dismutase (SOD) activity was higher than that of non-inoculated seedlings. AMF increased accumulation of lead in the root system. In the presence of 200, 500 and 1000 μg/g lead, there were higher lead concentrations in roots of mycorrhizal seedlings than in non-mycorrhizal seedlings. Lead was identified to dominantly deposit in the hyphal wall, the hyphal inner chambers, the hyphal inner-chamber membranes and the vacuole inner-chambers membrane. It is, therefore, hypothesized that lead stress can be decreased through the AM fungal cell. The ability of arbuscular mycorrhiza immobilizing lead can alleviate the phytotoxicity of lead to Z. mays seedlings.     

三种由Erwiniaspp．引起的新的花卉细菌病害

１９９４年在深圳农科中心花卉大棚中的巴西铁、文心兰和火鹤植株上，发现国内外尚未报道的细菌病害；巴西铁叶枯病，文心兰心腐病和火鹤叶枯病。病原细菌的主要细菌学性状试验结果表明，巴西铁叶枯病菌为菠萝欧氏杆菌（ＥｒｗｉｎｉａａｎａｎａｓＳｅｒｒａｎｏ）的一个菌株，文心兰心腐病和火鹤叶枯病均为兰欧氏杆菌［Ｅ．ｃｙｐｒｉｐｅｄｉｉ（Ｈｏｒｉ）Ｂｅｒｇｅｙｅｔａｌ．］的菌株之一。     

利用shRNA真核表达载体干涉雌性鸡胚性腺中芳香化酶基因(CYP19A1)的表达

本研究通过把构建的短发夹结构RNA(shRNA)真核表达载体导入鸡胚,检测鸡胚性腺分化期质粒载体在鸡胚体内代谢情况及雌性鸡胚性腺中芳香化酶基因(CYP19A1)mRNA表达效率,进而探讨利用该方法在鸡胚体内进行特定基因干涉的可行性.实验针对CYP19A1基因构建了4条特异性表达载体,一条非特异性表达载体.每个实验组选取45个新鲜种蛋作为实验材料进行胚盘下腔注射,并设立空白对照组.鸡胚发育12d时,检测各处理组鸡胚肝脏组织中质粒存在情况,并取其左侧性腺组织进行目标基因的荧光定量分析.研究结果表明,导入组在12日胚龄时所有鸡胚基因组中均可检测到绿色荧光蛋白基因(EGFP);荧光定量结果显示,导入特异性表达载体cyp-580、cyp-1083和cyp-1295后,对应雌性鸡胚性腺CYP19A1 mRNA表达效率显著低于空白对照组,干涉效率分别为:73％、52％和85％;特异性表达载体cyp-1403组CYP19A1mRNA表达效率与空白对照组相比有所降低但无显著性差异.本实验为诱导鸡胚性反转提供了新方法并建立了鸡胚发育期特定基因体内干涉新平台.     

山丘区小型水库大坝防洪标准的模糊综合评判方法

分析了现行小型水库防洪标准确定方法存在的问题。在此基础上,以总库容、灌溉面积、最大坝高和重要性为因素集,以大坝各等级为备择集,建立了小型水库防洪标准模糊综合评判模型。根据该模糊综合评判模型确定的大坝等级,以及大坝等级与防洪标准关系曲线,求得大坝的防洪标准。算例分析结果表明,该模型评价客观合理,有效地消除了过去在确定防洪标准中的人为性。     

Dechlorination of chloropicrin and 1,3-dichloropropene by hydrogen sulfide species: redox and nucleophilic substitution reactions

The chlorinated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) are extensively used in agricultural production for the control of soilborne pests. The reaction of these two fumigants with hydrogen sulfide species (H2S and HS-) was examined in well-defined anoxic aqueous solutions. Chloropicrin underwent an extremely rapid redox reaction in the hydrogen sulfide solution. Transformation products indicated reductive dechlorination of chloropicrin by hydrogen sulfide species to produce dichloro- and chloronitromethane. The transformation of chloropicrin in hydrogen sulfide solution significantly increased with increasing pH, indicating that H2S is less reactive toward chloropicrin than HS- is. For both 1,3-D isomers, kinetics and transformation products analysis revealed that the reaction between 1,3-D and hydrogen sulfide species is an S(N)2 nucleophilic substitution process, in which the chlorine at C3 of 1,3-D is substituted by the sulfur nucleophile to form corresponding mercaptans. The 50% disappearance time (DT50) of 1,3-D decreased with increasing hydrogen sulfide species concentration at a constant pH. Transformation of 1,3-D was more rapid at high pH, suggesting that the reactivity of hydrogen sulfide species in the experimental system stems primarily from HS-. Because of the relatively low smell threshold values and potential environmental persistence of organic sulfur products yielded by the reaction of 1,3-D and HS-, the effects of reduced sulfide species should be considered in the development of alternative fumigation practices, especially in the integrated application of sulfur-containing fertilizers.     

缓沉性水产膨化饲料加工工艺参数优化

该研究旨在研究不同加工工艺参数对缓沉性水产膨化饲料品质指标的影响规律,优化缓沉性水产膨化饲料的加工工艺参数。采用中心组合试验设计,选取调质物料含水率、膨化机螺杆转速和模头温度3个因素,吨料开孔面积固定为450 mm2/(t·h),调质物料含水率在23%～27%,模头温度范围在100～140 ℃,膨化机螺杆转速范围在180～300 r/min,对加工工艺参数进行优化。试验结果表明：随着调质物料含水率的升高,膨化饲料的容重逐渐降低,膨化率逐渐升高,在螺杆转速相同的条件下,不同模头温度的沉降速度的差异逐渐增大。随着模头温度的升高,膨化饲料的容重逐渐降低,膨化率逐渐升高,沉降速度逐渐降低,10 min沉水率先升高后降低。随着螺杆转速的增大,能耗逐渐升高,在调质物料含水率为23%～25%时,初始沉水率逐渐增大;当调质物料含水率大于25%时,10 min沉水率呈现先减小后增大的趋势。调质物料含水率和螺杆转速的交互项与初始沉水率呈负相关。调质物料含水率和模头温度的交互项与10 min内下沉率呈负相关。优化工艺参数：调质物料含水率为27%,模头温度110.68 ℃,螺杆转速265 r/min,在此条件下,平均容重为533.17 g/L,沉降速度为7.10 cm/s,初始沉水率为70.33%,10 min沉水率为99.00%。研究结果可为饲料企业生产缓沉性水产膨化饲料提供参考依据。