考虑初始含水率沿程不均匀分布的畦灌技术要素调控

畦田土壤初始含水率是影响灌水质量的重要因素之一,由降雨产流导致的畦田土壤含水率沿程不均匀分布是华北平原农田常见的现象。为探究土壤初始含水率空间变异性对畦灌水流运动以及灌水质量的影响,本文开展一维土柱入渗试验与二维土槽灌溉试验,结合WinSRFR地面灌溉模拟模型,优化求解初始含水率沿程不均匀条件下的畦灌技术要素。结果表明：畦田土壤初始含水率沿程增幅越大,畦灌田面水流推进速度越快,田面水流消退速度越慢;相较于初始含水率均匀分布,畦田土壤初始含水率沿程不均匀分布条件下,灌水效率和灌水均匀度有所下降,储水效率无明显变化;当畦田土壤初始含水率沿程增加时,灌水效率和储水效率受畦田长度、入畦单宽流量及改水成数的影响,而灌后土壤水分均匀度仅受畦田长度和单宽流量的影响;当畦田土壤初始含水率沿程由0.189 0 m³/m³均匀增大至0.464 3 m³/m³时,畦田长度L为85 m、改水成数G为6、单宽流量q为7.0 L/(m·s)时可取得最优灌水质量。本研究结果可为降雨产流带来的畦田土壤初始含水率不均匀条件下的灌水技...     

航天诱变种苗大小对当归物候特征、抗逆生理特性及药材产量的影响

为了探索航天搭载对当归成药特性的诱变效应,通过对航天诱变当归种子育成种苗分级移栽,研究种苗大小对当归成药期物候特征、抗逆生理特性、农艺性状及产量的影响.结果表明:种苗越大其返青率、移栽成活率、早期抽薹率越高,前期生长发育态势越好,表现为大苗成药栽培期株高、株幅、叶柄粗、复叶数、叶面积等生长发育指标优异;种苗大小对当归生...     

浅谈园林绿化树木病虫害的防治

文章分析了城市园林绿化树木病虫害发生的主要原因,提出了以生态学为基础,充分考虑园林绿化树木、病虫害及天敌三者之间的关系,以农业防治为主,从而控制有害生物,以保护园林绿化树木。     

乌兰浩特地区青杨天牛生物学特性及防治初步研究

文章对乌兰浩特市地区杨树蛀干害虫青杨天牛的生物学特性及防治方法进行了初步研究,防治方法中对树冠喷药法和人工修枝法进行了研究,并进行了药物筛选和效果对照,得出了结论,在青杨天牛的防治实践中有一定的应用价值。     

Changes in soil carbon stocks and related soil properties along a 50-year grassland-to-cropland conversion chronosequence in an agro-pastoral ecotone of Inner Mongolia, China

Land use change significantly influences soil properties.There is little information available on the long-term effects of post-reclamation from grassland to cropland on soil properties.We compared soil carbon(C) and nitrogen(N) storage and related soil properties in a 50-year cultivation chronosequence of grassland in the agro-pastoral ecotone of Inner Mongolia.Field surveys on land use changes during the period of 1955-2002 were conducted to build a chronosequence of cropland of different ages since the conversion from grassland.The results showed that soil C and N storage,soil texture,and soil nutrient contents varied with land use types and cropland ages(P<0.01).In the 0-30 cm soil layer,the soil organic carbon(SOC) density was significantly lower in the croplands(3.28 kg C/m2 for C50 soil) than in the grasslands(6.32 kg C/m2).After 5,10,15,20,35,and 50 years of crop planting(years since the onset of cultivation),the SOC losses were 17%,12%,19%,47%,46%,and 48%,respectively,compared with the grasslands.The soil total nitrogen(TN) density of the grasslands was 65 g N/m2,and TN density of the cropland soil was 35 g N/m2 after 50 years of crop planting.Both the SOC and TN densities could be quantitatively determined by a negative exponential function of cropland age(P<0.0001,R2=0.8528;P<0.0001,R2=0.9637).The dissolved organic carbon(DOC) content,soil available potassium(AK) content,clay content,and pH value were decreased;and the soil bulk density and sand content were increased since the conversion of grassland into cropland during the 50-year period.Our results show soil nutrients were higher in grassland than in cropland.The conversion of grasslands to croplands induced a loss of soil C storage and changes of related soil properties.The reclamation time of cultivated soil(cropland age) had significant effects on soil properties in the study area.     

桂花叶多糖提取工艺的优化

以水为溶剂提取桂花(Osmanthus fragrans)叶多糖,以多糖含量为指标,考察提取时间、提取温度、水料质量比对多糖提取率的影响,设计单因素试验和L9(34)正交试验优化提取工艺。结果表明,最佳提取条件为水料质量比60∶1、提取温度90℃、提取时间4 h,在此条件下桂花叶多糖的提取率为11.35%。     

Coagulation Removal of Phthalic Acid Esters Environmental Hormones by Polymeric Phosphate Ferric Sulfate

Based on the strong poly role of phosphate on polymeric ferric sulfate (PFS), with PFS and Na 2HPO 4 as raw materials, a new type of composite flocculant polymeric phosphate ferric sulfate (PPFS) was developed. The structure of PPFS was characterized by IR and SEM, and the mechanism of flocculation was analyzed. The factors affecting phthalic acid esters (PAEs) removal were discussed, including dosage, nPO 43-/nFe3+and alkalization degree. The results indicate that PPFS has good removal effect to PAEs. When the dosage is 70 mg·L-1, nPO 43-/nFe3+ is 0.3 and alkalization degree is 30%, the removal rate of dimethyl phthalate, diethyl phthalate, dibutyl phthalate and bis (2 ethylhexyl) phthalate are 67.93%,84.55%,90.88%,88.69%, respectively.     

黄芪对黑曲霉植酸酶代谢活性的影响

利用FeSO4-钼蓝法研究了中草药黄芪(Astragalus membranaceus)粉末、黄芪水提取液对黑曲霉(Aspergillus niger)植酸酶在固体培养基和液体培养基中代谢活性的影响.结果表明,在0.03 g/mL的黄芪粉末和0.03 g/mL的黄芪水提取液作用下,44h时黑曲霉中植酸酶活性最高.与对照相比,固体培养基中加入黄芪粉末和黄芪水提取液的吸光度分别提高了33.6％和37.8％,液体培养基中加入黄芪粉末和黄芪水提取液的吸光度分别提高了21.0％和28.7％.在最佳培养时间,植酸酶活性均随着黄芪浓度的增大而呈下降趋势,其中加入黄芪粉末的液体培养基变化幅度最大,植酸酶活性浓度0.01 g/mL是浓度0.05g/mL的1.64倍;加入黄芪水提取液的液体培养基中植酸酶活性浓度0.01 g/mL是浓度0.05 g/mL的1.54倍;加入黄芪粉末和黄芪水提取液的固体培养基中植酸酶活性浓度0.01 g/mL分别是浓度0.05g/mL的1.50和1.42倍.     

Preparation of Activated Carbon from Cotton Stalk Using Potassium Hydroxide as Activation Agent

以棉花秸秆为原料,采用KOH活化法制备活性炭样品,探讨了炭化、活化及后处理过程中各实验条件对活性炭样品性能的影响.综合考虑活性炭样品的性能及得率,得出较优的实验条件为:炭化温度450～500℃、碱炭比值1.0、活化温度800℃、活化时间120 min;在较优条件下制得活性碳的比表面积2 312m2/g,碘吸附值1 936 mg/g,亚甲基蓝吸附值392 mg,/g;孔径分布以微孔为主;表面含有羟基(-OH)、活泼氢(-H)等基团.     

新型优质发酵及酶解饼粕蛋白饲料资源开发利用现状与展望

近年来,我国蛋白饲料资源对外依存度逐年提高,饲料资源的短缺已成为制约我国饲料工业和养殖业发展的瓶颈。我国各类饲用饼粕、尤其是杂粕资源丰富,但由于其饲用价值不高,或含有多种毒素,使其在饲料的工业化生产中没有得到高效合理的利用。因此,开展蛋白饲料原料开发与高效利用关键技术研究非常迫切。微生物发酵和酶解由于具有独特的优势,已得到研究者和业界的重视,并取得了一系列进展和成果,但仍存在许多需要解决的技术问题。文章针对上述问题,对微生物发酵与酶解技术在蛋白饲料资源开发领域应用的特点和研究现状进行了综述,提出了该领域进一步研究和发展的方向。