温度和水分对华中地区菜地土壤氮素矿化的影响

为研究华中地区菜地土壤的矿化特征和矿化规律,拟定菜地土壤合理的氮肥施用量,本文以华中地区两种典型菜地土壤——黄棕壤和潮土为研究对象,利用室内连续培养试验研究了温度、水分对菜地土壤矿化的影响。结果表明,黄棕壤的矿化速率和氨化速率均随着温度的升高而升高;硝化速率在15%和25%含水量下随温度的升高而升高,而在35%含水量下随温度的升高而降低。潮土矿化速率在15%含水量时随温度的升高而升高,而在25%和35%含水量下随温度的升高先增加后减小;硝化速率在15%和35%含水量时随温度的升高而增加,25%含水量时随温度的升高先增加后降低;氨化作用随温度的升高而降低。黄棕壤的矿化量在含水量为25%、温度35℃时高达34.9 mg.kg 1;潮土的矿化量在含水量为25%、温度为25℃时最高,为63.9mg.kg 1。不同温度下潮土矿化量均大于黄棕壤。黄棕壤的氨化速率随含水量的增加而增加,硝化速率随含水量的增加而降低,矿化速率则在含水量25%时最大。潮土的氨化、硝化和矿化作用随水分变化不明显。本研究还发现,25%的含水量是黄棕壤微生物活性的水分临界点,潮土的水分临界点不明显。通过对土壤氮素的矿化速率与水分含量和温度之间的函数关系模拟发现,黄棕壤模拟效果好于潮土。     

硝酸稀土添加剂对家兔心电图的影响

将24只家兔随机分为对照组和3个试验组,每组6只,每只每天分别补饲含0,10,20,30mg/kg的硝酸稀土添加剂配合饲料17.5g,补饲5d后,采用肢体导联测定心电图.从第16天开始,剂量改为0,20,40,60mg/kg,第20天时再测定.试验期30d.结果表明:1)波型上主要表现为:心电轴大多左移,大小不等的纤维波、Q异常波、QRS波、T波切迹或呈双峰;2)20mg/kg试验组与对照组心率无差异外,其他试验组与对照组差异显著(p<0.05);3)P-Q间期,随质量浓度的增加而时间缩短,T波时间延长;P波、QRS波群、Q-T间期时限变化不大.P波在10mg/kg下与对照组比较差异极显著(p<0.01),20mg/kg的质量浓度组差异显著(p<0.05),其他浓度组差异不显著.T波持续时限在10,40mg/kg下与对照组比较差异极显著(p<0.01),20,60mg/kg的质量浓度组与对照组比较差异显著(p<0.05).4)P波、QRS波、T波电压随稀土质量浓度的增高,表现为“前低中高后低”趋势,稀土质量浓度达60mg/kg时,各波电压呈下降趋势.     

7种稀土小檗碱配合物对4种农作物病菌的抑菌性及急性毒理性的研究

研究开发了7种新型稀土配合物。使用差热热重和红外表征了配合物,采用最低抑菌浓度实验,研究了配合物对4种（番茄溃疡病菌、向日葵菌核病菌、尖孢镰刀菌和胡萝卜黑斑病菌）农作物病原菌的敏感性;采用急性经口毒性和急性经皮毒性试验,考察其急性毒性。7种配合物均为低毒性药物,并且抑菌效果好。对向日葵菌核病菌最低抑菌浓度均为0.125 mg/mL。对番茄溃疡病菌抑菌效果最好的是Ce(NO3)3(B)3、Gd(NO3)3(B)3,最低抑菌浓度是0.125 mg/mL。对尖孢镰刀菌抑菌性最好的是La(NO3)3(B)3、Gd(NO3)3(B)3和Y(NO3)3(B)3,最低抑菌浓度是0.5 mg/mL。对胡萝卜黑斑病菌抑菌性最好的是Gd(NO3)3(B)3,最低抑菌浓度是0.5 mg/mL。结果表明7种新型稀土小檗碱配合物是一类广谱、高效、低毒的杀菌剂。     

Study on Absorption Distribution of Rare Earth Elements in Crops With Rare Earth Fertilizer

The absorption and content distribution of 5REs (La,Ce,Nd,Y and Gd) in 3species of crops (corn,paddy and soybean )have been studied. The results show that there exists the positive relationship between capability of rare earth elements being absorbed by crops and available rare earth elements in soil. Generally,content distribution of rare earth elements in crops are root >leaf >stem >fruit. Distribution of unitary rare earth elements in root is La>Ce>Nd>Y>Gd,and in leaf ,stem and fruit is Ce>La>Nd>Y>Gd. It is proved that light rare earth elements absorbed are easier than heavy rare earth elements. In addition ,capability of rare earth elements absorbed in crops growing is seedling >ramification >maturity . In a word,the data of pot experiment show that most of bioaccumulation in root . Thus, it is helpful to agricultural application of rare earths.     

稀土拌种对玉米产量的影响

试验表明,玉米使用不同量的农用稀土拌种均有增产效果。以０４ｇ稀土／ｋｇ种子拌种增产率最高,为１５８％。其次,０８ｇ稀土／ｋｇ种子拌种增产率为１０８％。玉米稀土拌种百粒重、穗长、穗粗与产量直接通径作用大。穗长和百粒重的互作效应以及百粒重、穗长、穗粗单效应成为影响产量的主要因素。     

轻稀土硝酸盐对小白菜中溴氰菊酯降解的影响

运用单一轻稀土硝酸盐及其不同混合溶液喷施或灌施小白菜,10d后喷施溴氰菊酯,喷药3d后检测叶片中农药残留量。结果表明,高剂量稀土硝酸盐溶液(≥1.8×10-5mg·L-1)抑制溴氰菊酯的降解,低剂量稀土硝酸盐溶液(≤1.8×10-6mg·L-1)则促进溴氰菊酯的降解,且稀土溶液与农药的不同处理方式(喷施,灌施或处理的时间顺序)对小白菜中溴氰菊酯降解的促进或抑制作用均产生不同影响。     

稀土元素在土壤-植物系统中行为与归宿的研究

对当前农用稀土安全性评价研究前沿的土壤-植物系统中稀土元素的行为与归宿研究予以综述。归纳出土壤pH、氧化还原电位、有机质、阳离子交换量、粘粒矿物等均影响外源稀土在土壤中吸附性能和迁移性、稀土元素各形态转化与可给性,植株或农作物体内聚集稀土元素的能力依赖于植物种类、土壤介质中稀土含量以及成土母质和相应的生境。与土壤介质相比,植株中单一稀土元素含量可存在一定的分异性,并且植株对单一稀土元素的吸收与运移具有选择性。为此有必要从细胞水平和分子水平进一步研究单一稀土元素在植物体内的存在状态和运移特性,同时深入研究稀土肥料的不同方式施用后,田间状况下农作物体内稀土元素的吸收及运移情况,特别是籽实中稀土元素的累积。     

利用原状土柱研究华中地区菜地土壤氮素的矿化规律

本文以华中地区两种典型的菜地土壤-黄棕壤和潮土为研究对象,采用原状土柱系统,综合考虑了大气干湿沉降、灌溉、作物携出及淋失等氮素的影响因素,通过菜地轮作(2年8季蔬菜),研究了两种土壤氮素的矿化特性。结果表明,黄棕壤氮素的矿化总量和矿化速率分别为134.52 mg和0.04 mg kg-1 d-1;潮土的矿化总量和矿化速率分别为185.93 mg和0.06mg kg-1 d-1。研究还发现,土壤氮素的矿化受季节影响较大,春夏季土壤氮素的矿化量和矿化率明显高于秋冬季,同时耕作能明显增加菜地土壤氮素的矿化量与矿化速率。试验期间通过大气沉降输入的氮素总量为118.89 mg,是氮素输入的主要方式,而湿沉降约为氮素沉降总量的81.05%。黄棕壤和潮土氮素蔬菜作物氮素的携出量分别为178.96和230.37 mg;氮素淋失量分别为103.32和113.27 mg。     

镧对红壤主要微生物种群的影响

A greenhouse experiment was conducted to investigate the effect of surface film-forming material(SFFM),a mixture of 16-18-octadecanols by emulsification,on water evaporation,Air-dired soil with distilled water was incubated firstly for 7days to reestablish soil biological activity and then for another 7 days atfer treated with SFFM at rates of 0,1,2,4,6,8 and 8 g m^-2，respectively,Everyday during the 7-day incubation after addition of SFFM,water losses due to evaporation were measured by an electronic balance.The rate of water evaporation with the addition of SFFM was reduced significantly compared with the control treatment and the effectiveness of SFFM on water evaporation reduced with time.According to the equation expressions of the effect of SFFM on water evaporation ,the half-life of effectiveness of SFFM on water evaporation was introduced and calculated to analyze quantitative relationship between the effectiveness of SFFM on water evaporation and the addition rate of SFFM.The calculaed half-life increased with the addition rate of SFFM and the confidence of the calculated values of the half-life was high,suggesting that the half-life of effectiveness of SFFM on water evaporation could be described quantitaively and may be helpful for ameliorating application method of SFFM and screening surface-film forming materials in order to improve nitrogen fetilizer use efficiency in floodey rice fields.