小白菜潮汐式栽培专用基质的筛选

对3种不同栽培基质和常规栽培基质（市场销售）在潮汐式灌溉模式下进行小白菜栽培试验,比较小白菜的植物学性状,筛选出适用于潮汐式灌溉的小白菜专用型栽培基质。研究结果表明,处理2（40%茶渣蚓粪、20%泥炭、20%蛭石、20%珍珠岩）培育的小白菜株高、生物量、株幅、SPAD 值均显著优于其他处理,栽培效果显著提高,可推荐作为潮汐式灌溉小白菜栽培的专用型基质。     

不同营养液浸泡花泥对切花寿命的影响

以1％蔗糖＋200 mg/L硫酸铝＋300 mg/L硝酸钙＋200 mg/L磷酸二氢钾＋10mg/L6-BA为基本营养液,分别添加30 mg/L的苯甲酸、水杨酸和山梨酸为不同处理,以蒸馏水为对照浸泡花泥,保鲜月季、切花菊,香石竹、非洲菊等切花,研究这3个处理的保鲜效果.结果表明,各处理均可使切花延长寿命.但对不同切花品种,各处理的效果有差异,对月季、切花菊、非洲菊切花的寿命影响,处理3＞处理2＞处理1,即添加山梨酸的营养液效果优于添加水杨酸的,更优于添加苯甲酸的效果;对香石竹切花的影响则为处理3＞处理1＞处理2.     

菌渣纤维素降解菌的筛选与鉴定

为了寻找高效纤维素降解菌,提高菌渣堆肥微生物发酵效果,促进菌渣高效循环利用,从不同地点堆放的杏鲍菇菌渣中采集样品,利用羧甲基纤维素钠培养基分离纤维素降解菌,结合纤维素刚果红水解圈测定、滤纸条降解试验和纤维素酶(滤纸酶FPA、内切葡聚糖酶CMCase、外切葡聚糖酶C1、葡萄糖苷酶β-Gase)活性测定,筛选到4株(FB7、CB1、BC11、BC12)具有高效纤维素降解能力的细菌,经16S rDNA序列分析,鉴定FB7、CB1为枯草芽孢杆菌,BC11为链霉菌属Streptomyces albus,BC12是丛毛单胞菌属的Comamonas_jiangduensis,其中FB7降解能力强,可将滤纸条降解成糊状(10 d),纤维素酶活力很高,摇瓶发酵4 d后FPA、CMCase、C1酶、β-Gase的酶活分别为22.81、314.50、2.78、188.09 U·g^-1。复合菌剂CB1+BC11+FB7的FPA、CMCase、C1酶、β-Gase的酶活高于其他各组合,为31.56、133.63、2.31、217.21 U·g^-1,与FB7相比分别提高了38.4%、11.2%、178%、70.3%,将复合菌CB1+BC11+FB7接种到菌渣堆肥中,与对照相比,能快速提高堆体温度,且在翻堆后能更好地维持堆温。     

水产食品中甲醛风险评估研究进展

甲醛对人的呼吸、致敏和免疫、神经、内分泌系统均有影响,并有生殖毒性和致癌作用.本文主要从水产食品安全角度,根据风险评估理论,从甲醛对人体健康的危害、暴露评估、风险评估结果的不确定性和风险管理措施诸方面,探讨甲醛与人体健康之间的关系,综述水产食品中甲醛危害风险评估的研究进展.     

The effects of density and artificial substrate on intensive shrimp Litopenaeus vannamei nursery production

Recirculating aquaculture systems (RAS) can be installed indoors, allowing year-round production of tropical animals in nearly any climate. A nursery phase is commonly used in Litopenaeus vannamei production since it allows for enhanced biosecurity and better quantification of animals while reducing space requirements. However, it is unclear whether animal density and inclusion of artificial substrate may improve shrimp performance during the nursery phase. In this experiment, we compared shrimp production parameters in two stocking densities with or without the use of an artificial substrate by creating four treatments: low-density LD; 1500 PL/m⁻³, low-density with substrate LDS, high-density HD; 3000 PL/m⁻³), and high-density with substrate (HDS). The LDS and HDS treatments included 0.46-m² of high-density polyethylene 2.5-cm mesh as a substrate, which increased the tank surface area by 21 %. Each treatment was randomly assigned to four 160-l culture tanks, each with a biofilter. The shrimp had an initial weight of 4 mg and were grown for 50 days. The low-density treatments had significantly higher dissolved oxygen (DO) and pH than the high-density treatments (P ≤ 0.001). Specifically, LDS had the highest DO and pH followed by the LD, HD, and HDS treatments, respectively. High-density treatments had significantly higher NO₂-N levels than low-density treatments during week 2 of the experiment when an unusually high concentration of nitrite was observed. FCR was significantly lower in both low-density treatments than in high-density treatments. At harvest, the total biomass (kg m⁻³) was significantly higher in high-density treatments than in low-density treatments (P ≤ 0.001), and the HDS treatment had a significantly greater biomass output than HD. Producers should consider artificial substrate and higher densities during nursery production to maximize shrimp production; however, the effects on water quality should also be taken into account.     

Substrate concentration affects the in vitro metabolism of 17-hydroxyprogesterone by ovaries of the carp,Cyprinus carpio

Carp ovarian tissue was incubated with ³H-17-hydroxyprogesterone in the presence of 0, 0.1, 1, 10, and 100 μg ml⁻¹ unlabeled 17-hydroxyprogesterone. The pattern of metabolites formed showed a marked variation with substrate concentration. Formation of glucuronide and sulphate conjugates was important only at low substrate concentration. At high substrate concentration (10 and 100 μg ml⁻¹) 17,20α-dihydroxy-4-pregnen-3-one was the major metabolite, but at intermediate concentrations polar 7α-hydroxypregnanetetrols predominated. The results support the hypothesis that at low substrate concentrations conjugating, 5α-reducing and 7α-hydroxylating enzymes, of high activity but low capacity, act as scavengers to deactivate any steroids formed during the relatively low pituitary gonadotrophin secretions which are necessary for oocyte development, but that during the prespawning gonadotrophin surge when high levels of substrate are present these enzymes are saturated and 17,20α-dihydroxy-4-pregnen-3-one (17,20αP) becomes the major ovarian steroid. The possible role of 17,20αP during oocyte final maturation requires further examination.     

Competition for food between Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) over different substrate types

Abstract –  Food consumption by Eurasian perch ( Perca fluviatilis L.) and ruffe ( Gymnocephalus cernuus [L.]) was studied in single and mixed-species treatments in the laboratory, where alternative food resources, chironomids and zooplankton, were offered simultaneously. The effects of structural complexity, which was represented by substrate grain size, and of feeding level on food consumption were analysed. Across all experiments, the outcome of competition between perch and ruffe depended on food abundance and on the structural complexity of the environment. Perch and ruffe both changed their food consumption in the presence of a heterospecific competitor. With high food supply, perch consumed more benthic food than ruffe. With low food supply, the consumption of perch decreased strongly, while that of ruffe remained high on fine sediment. Under all conditions tested, the mechanism of competition appeared to be of interference rather than of exploitative nature. It is suggested that with decreasing lake productivity caused by re-oligotrophication, habitat shifts of both species will occur, which will alleviate interspecific competition. Ruffe will forage over fine sediment and perch over coarse sediment, whereby both species will achieve the highest foraging efficiency under conditions of low food supply.     

植物收割对人工湿地基质酶活性的影响

研究了7月份植物收割对人工湿地基质磷酸酶、脲酶、蛋白酶、脱氢酶活性及养殖废水中总氮(TN)、总磷(TP)、COD去除率的影响。结果显示:植物收割后磷酸酶、脲酶、蛋白酶活性开始增高,分别于第20天(13.7 mg/100 g)、第16天(1.9 mg/100 g)、第12天(61.7 mg/100 g)达到最大值,均于第28天(10.1 mg/100 g、1.1 mg/100 g、43.2 mg/100 g)恢复到收割前水平。脱氢酶活性在植物收割后第4天(142.3μL/100 g)降到最小值,此后开始增高,第16天(249.5μL/100 g)达到最大值,于第24天(195.6μL/100 g)恢复到收割前水平。净化效果研究表明,植物收割后TP、TN去除率开始增高,分别在植物收割后第20天(75.1%)、16天(60.6%)达到最大值,均于第28天(51.1%、34.1%)恢复到收割前水平。COD去除率在收割后第4天(25.3%)降到最小值,此后开始增高,第16天(70.2%)达到最高值,第24天(46.5%)恢复到收割前水平。     

非洲菊保护地无土栽培研究进展

非洲菊为世界五大切花之一,全球栽培面积逐年扩大。阐述了非洲菊无土栽培中栽培基质、营养液配方2大因素对非洲菊生长发育、产量和质量的影响,以期为非洲菊的标准化生产提供参考依据。