临夏州不同种植区马铃薯播种适期研究

临夏州马铃薯种植区域主要分布在无灌溉条件,年降雨量不足200 mm的干旱山地和年降雨量约600 mm的山二阴地,以及灌溉便利,年降雨量在500 mm左右的川塬区。通过种植区域、播种时间和栽培措施3因素对比试验,以产量、病害损失和经济效益做综合分析对比,得出临夏州春旱较频繁的干旱山地和山二阴地区应适当推迟播期至5月上旬左...     

Detection of citrus psorosis-ringspot virus using RT-PCR and DAS-ELISA

Psorosis, sometimes also associated with ringspot symptoms, is a widespread and damaging disease of citrus in many parts of the world including South America and the Mediterranean basin. We describe the application of RT-PCR and DAS-ELISA diagnostics to an isolate of citrus ringspot virus (CtRSV-4) and other virus isolates associated with this disease. Fragments of cDNA from bottom-component RNA of CtRSV-4 were cloned and sequenced, and PCR primers were designed, 5'ACAATAAGCAAGACAAC upstream, and 5'CCATGTCACTTCTATTC downstream. RT-PCR experiments using these primers allowed detection of CtRSV-4 in infected citrus leaves down to a tissue dilution of 1/12 800 representing 2 μg of tissue, and less sensitive detection of the related citrus psorosis-associated virus (CPsAV90-1-1) and four other psorosis isolates from Argentina and the USA. In addition, CtRSV-4 particles were partially purified from local lesions in Chenopodium quinoa, and the preparations used to raise a rabbit antiserum. The antiserum was absorbed with extracts of healthy C. quinoa leaves, and a DAS-ELISA kit was prepared and tested for detection of CtRSV-4, CPsAV90–1-1, and other psorosis isolates from Argentina, the USA, Italy and Spain. The ELISA detected CtRSV-4 down to a tissue dilution of 1/1600, and most other psorosis isolates down to dilutions of 1/200–1/800. Three of a total of 20 heterologous isolates were consistently negative. Comparison of the PCR and ELISA results suggests that both methods can be used for detection of a range of psorosis isolates, but that variation of the viruses in the field might cause problems for any one diagnostic test.     

野生龙葵果中营养成分的研究

本研究对野生龙葵果营养成分进行了比较全面地分析测试,对矿物质及维生素含量进行分析的基础上,对野生龙葵果的其它营养成分进行了分析,并与一些常用果蔬进行了对比研究。结果表明,野生龙葵果含有丰富的营养成分。     

青海省海南州高寒草地荒漠化治理技术与对策

总结了海南州高寒干旱草地荒漠化特征和成因,分析出气候变化、毁草开荒、超载过牧、鼠类危害、利用不当、执法不严等是草地荒漠化的主要原因,通过对荒漠化草地实行人工补播优良牧草、灭除毒草、消灭鼠害、禁牧封育、暖棚养畜、营造饲料护牧林等措施,提出了防止草地荒漠化的对策及治理技术.     

成熟期短时渍水胁迫对烤烟碳氮代谢关键酶及主要碳、氮化合物含量的影响

以烤烟云烟97为材料,采用田间试验研究了成熟期短时渍水处理对烤烟碳氮代谢关键酶活性及主要碳、氮化合物含量的影响。结果表明,在烤烟成熟期渍水处理3 d,中部叶片硝酸还原酶活性低于对照,降幅为20.39%;转化酶和淀粉酶活性高于对照,增幅分别为33.14%,56.70%;烟叶淀粉、总氮和烟碱含量有降低趋势,分别下降了2.9,0.74,0.77个百分点,而总糖和还原糖含量有增加趋势,分别上升了1.33,0.46个百分点。说明渍水胁迫使叶片生理代谢紊乱,氮代谢减弱,碳水化合物积累减少。研究结果有助于从生理生化角度揭示成熟期渍水胁迫对烤烟生长和品质形成影响的机制。     

Lactobacilli counts in crop,ileum and caecum of growing broiler chickens fed on practical diets containing whole or dehulled sweet lupin (Lupinus angustifolius) seed meal

1. Four experiments with growing broiler chickens were carried out to study the effects of the inclusion in their diets of lupin (Lupinus angustifolius ) seed meal on E. coli and lactobacilli counts in crop, ileum and caeca at 3 or 4 weeks of age. 2. Diets were formulated to contain the same amounts of metabolisable energy (12.55 MJ/kg) and protein (210 g/kg). Raw whole (heat-untreated) or dehulled sweet (low in alkaloids) lupin seed meal (400 and 320 g/kg respectively) were used to prepare the lupin-based diets, whose protein content was completed with either defatted soyabean meal or casein. 3. Final body weight and food intake of chickens fed on whole lupin seed meal diets were lower than controls, but gain: food ratios were not different. However, birds given the diet with dehulled lupin seed meal had similar body weight, food intake and gain: food values as those of controls. 4. While E. coli counts were not affected, lactobacilli numbers were consistently increased compared to controls in all intestinal sections of chickens fed on the whole or dehulled lupin-based diets, irrespective of the age of the birds or the presence of soyabean meal or casein in the diet. The lactobacilli species isolated were: Lactobacillus fermentum, L. acidophilus, L. salivarius and L. brevis 5. The results suggest that the use of whole or dehulled sweet lupin seed meal in diets for growing broilers might enhance the growth of lactic acid-fermenting bacteria in the gut.     

贵南县高寒草地荒漠化及其控制技术与措施

通过简述贵南县高寒干旱区草地类型、分布区域及荒漠化特征 ,从气候变化、鼠害、盲目开垦及超载过牧等自然、人为因素方面 ,分析总结了草地荒漠化引发机理 ,提出了防止草地荒漠化的对策及治理技术。     

乡土植物在青海省高等级公路绿化中的应用

乡土植物是在长期的系统演化过程中,经过严格自然选择的优胜者,它们与当地的气候、土壤相适应,具有适应性广、抗病虫害能力高、抗逆性强等特点。本文通过总结近年来乡土植物在青海公路绿化中的实践经验,就如何合理规划应用乡土植物进行了阐述。     

Flash X-ray Microscopy

Soft x-ray contact microscopy, utilizing single-shot exposures of approximately 60 nanoseconds duration in polymethyl methacrylate, has been realized with a resolution of 300 angstroms. The radiation spectrum is intense in the "window" between 23 and 44 angstroms where water is transparent compared to biological materials, and therefore permits viewing of wet samples.     

Effects of feeding practical diets containing different protein levels, with or without fish meal, on growth, survival, body composition and processing traits of male and female Australian red claw crayfish (Cherax quadricarinatus) grown in ponds

Four practical diets containing 2% of crude protein (CP) (180 and 280 g kg^?1), with or without menhaden fish meal (FM), were fed to Australian red claw Cherax quadricarinatus during a 97‐day feeding trial. Growth, survival, body composition and processing traits of pond‐cultured red claw were determined. Juvenile red claw (mean individual weight of 5.75 ± 3.3 g) were randomly stocked into twelve 0.04‐ha ponds at a rate of 1000 per pond (25 000 ha^?1), and each diet was fed to three ponds. At harvest, the final mean weight of red claw fed Diet 4 (0 g kg^?1 FM and 280 g kg^?1 CP) and Diet 3 (113 g kg^?1 FM and 280 g kg^?1 CP) was significantly (P < 0.05) higher (62.4 and 58.5 g, respectively) than red claw fed Diet 1 (73 g kg^?1 FM and 180 g kg^?1 CP; 51.7 g) and Diet 2 (0 g kg^?1 FM and 180 g kg^?1 CP; 53.0 g). Red claw fed diets containing 280 g kg^?1 CP, with or without FM, had significantly higher percent weight gain (894 and 959%, respectively) compared to red claw fed 180 g kg^?1 CP, with or without FM (778 and 799%, respectively). Feed conversion ratio, percent survival, and total yield among treatments, which averaged 3.55, 65.2%, and 724 kg ha^?1 overall, were not significantly different. Results from this study indicate that pond‐cultured red claw stocked at 25 000 ha^?1 can be fed a practical diet containing 280 g kg^?1 CP with 0 g kg^?1 FM if a combination of plant‐protein ingredients (soybean meal, distillers’ dried grains with solubles, and milo) is added; however, if the percentage of dietary protein level is 180 g kg^?1, growth is reduced even if FM is added at 73 g kg^?1 of the diet. Use of diets containing plant‐protein sources may help reduce diet costs to producers and thereby, increase profits.