贵州茶区土壤养分状况综合评价

应用SPSS统计软件,对贵州全省70个茶园土壤样品8项养分指标进行主成分分析,按累计贡献率达到85%以上提取了4个主成分,并求出各土壤养分的4个主成分综合得分。并对综合得分以欧氏距离为衡量土样间差异大小的指标,采用类平均法进行聚类分析。将70个土样分为Ⅰ、Ⅱ、Ⅲ、Ⅳ等级,第Ⅰ类为养分丰富型土壤,其各项养分指标最高,综合得分范围0.63≤F≤1.08,所占比例9.83%;第Ⅱ类为养分较丰富型土壤,其综合得分范围0.10≤F≤0.53,所占比例29.51%,相对Ⅰ类,有机质和全磷含量相对不足;第Ⅲ类茶园土壤肥力一般,其综合得分范围-0.32≤F≤0.02,所占比例36.07%;第Ⅳ类土壤各养分因子均缺乏,为养分缺乏型茶园土壤。     

Laboratory Assessment of Nostoc 9v (Cyanobacteria) Effects on N2 Fixation and Chemical Fertility of Degraded African Soils

The potential of Nostoc 9v for improving the nitrogen (N)₂–fixing capacity and nutrient status of semi‐arid soils from Tanzania, Zimbabwe, and South Africa was studied in a laboratory experiment. Nostoc 9v was inoculated on nonsterilized and sterilized soils. Inoculum rates were 2.5 mg dry biomass g^?1 soil and 5 mg dry biomass g^?1 soil. The soils were incubated for 3 months at 27 °C under 22 W m² illumination with a photoperiod of 16 h light and 8 h dark. The moisture was maintained at 60% of field capacity. In all soils, Nostoc 9v proliferated and colonized the soil surfaces very quickly and was tolerant to acidity and low nutrient availability. Cyanobacteria promoted soil N₂ fixation and had a pronounced effect on total soil organic carbon (SOC), which increased by 30–100%. Total N also increased, but the enrichment was, in most soils, comparatively lower than for carbon (C). Nitrate and ammonium concentrations, in contrast, decreased in all the soils studied. Increases in the concentration of available macronutrients were produced in most soils and treatments, ranging from 3 to 20 mg phosphorus (P) kg^?1 soil, from 5 to 58 mg potassium (K) kg^?1 soil, from 4 to 285 mg calcium (Ca) kg^?1, and from 12 to 90 mg magnesium (Mg) kg^?1 soil. Positive effects on the levels of available manganese (Mn) and zinc (Zn) were also observed.     

我国农机安全互助保险发展存在的问题及对策

农机互助保险是现代农业经济发展的产物,是现代农机管理的重要工作内容。为了加快我国农机互助保险事业的健康发展,在分析当前农机互助保险发展现状的基础上,指出了农机互助保险存在的5个方面的问题,并从立法、管理和宣传等3个层面探讨了农机互助保险的发展对策。     

基于光谱分析的温室黄瓜营养状态的研究

黄瓜在温室栽培面积中占有很大的比重,监测温室黄瓜营养状态非常重要。因此,利用光谱分析技术对叶片所含的化学成分进行测量,主要包括建模与预测两步,采用基于BP算法的人工神经网络和支持向量机进行光谱的定量分析,探索基于光谱分析的整株光谱判断温室黄瓜的营养状态。研究结果表明,基于 BP 算法的人工神经网络和支持向量机所建立的回归模型,在一定程度上提高了模型的自预测能力和实际预测能力。     

鲜食甜玉米对比试验及生育期气象条件分析研究

开展甜玉米品质对比试验研究,比较分析各参试甜玉米品种的性状、品质、口感,筛选出适合呼和浩特地区推广种植的甜玉米品种,为种植户提供专业的技术指导。主要依据试验基地小区分区试验,对试验甜玉米品种进行全生育期观测,每个品种采用田间随机选样4组,每组依次选取10株进行观测,主要针对生长状况、产量结构各要素进行测定,根据专家现场鉴评,对每个品种口感进行综合测评。结果表明：15个甜玉米品种中,‘万彩甜糯118’、‘禾甜糯2’、‘金糯628’、‘万糯2018’、‘美玉加甜糯36号’几个品种果穗大小均匀,籽粒饱满,排列整齐,并且甜糯可口,品质较好;‘禾甜糯2’属于口感型玉米,但是穗长较小,因此建议种植户选用时,如果追求甜玉米穗长和产量,应该尽量摒弃;‘美玉加甜糯36号’是早熟玉米,口感既糯又香甜,但是由于生育期短,因此种植时一定要合理结合销路进行种植,以防玉米过早衰老;‘万彩甜糯118’、‘金糯628’、‘万糯2018’属于中熟品种,建议大面积推广种植。综合甜玉米品种特性,甜玉米生育期越长,口感越佳,一般早熟甜玉米口感较差,中晚熟甜玉米口感比较好,杂交系甜玉米比自交系甜玉米更甜更糯,本次试验中,发现黄白相间、彩糯玉米等口感都比较好;甜玉米受干旱、高温、连阴天等不利天气影响较大,在生长期如果水肥条件太差不利于玉米快速生长,在开花期至乳熟期,如果出现高温或者连阴天,将会影响玉米授粉,同时不利于玉米结籽。     

Effects of vitamin C supplementation on growth performance and antioxidant status of layer ducklings

The study was conducted to evaluate the effects of increasing dietary vitamin C supplements on growth performance, antioxidant status and humoral immunity of layer ducklings. The results showed that the body weight and daily body weight gain of ducklings increased (p < 0.05) with increasing dietary vitamin C supplementations and reached a maximum at 400 mg vitamin C/kg feed. The dietary vitamin C supplementations reduced the malondialdehyde concentration (p < 0.05) and increased the activities of superoxide dismutase and glutathione peroxidase (p < 0.05) in serum and liver of ducklings at day 5 and 28. Additionally, feeding 400 mg/kg or 800 mg vitamin C/kg feed increased IgM and IgA concentrations in sera (p < 0.05) and serum IgG concentrations increased (p < 0.05) following supplementation in concentrations of 150-800 mg vitamin C/kg feed. In conclusion, the results suggested that dietary vitamin C supplements of 400 mg/kg feed provide optimal effects on growth performance, antioxidant status and parameters of humoral immunity.     

农村小型水利工程管理的发展现状及对策

水利是国民经济的基础产业,是新时期建设社会主义新农村的基础。随着农村经济体制改革的深入,农村小型水利工程建设与管理中存在的权责不明、投入不足、发展滞后、管理不善、效益衰减等问题越来越突出,已成为提高农业综合生产能力的主要制约因素。文章分析了我国现行农村小型水利工程管理普遍存在的问题,并提出了系列具有针对性的建设措施,探讨了农村小型水利在规划、建设、管理与改革等方而的些具体做法。     

The effect of selected microbial strains on internal milieu of broiler chickens after peroral administration

The aim of this work was to investigate the effect of probiotic preparation with multi-strains composition (Lactobacillus delbrueckii ssp. bulgaricus LAT 187, Lactobacillus acidophilus LAT 180, Lactobacillus helveticus LAT 179, Lactobacillus delbrueckii ssp. lactis LAT 182, Streptococcus thermophilus LAT 205 and Enterococcus faecium E 253) on internal milieu, antioxidant status and body weight of broiler chickens. Chickens were divided into three groups (C, control; E1 and E2, experimental groups). Experimental chickens received the probiotic preparation in drinking water. Probiotic preparation caused a significant increase of serum calcium and potassium content. In the group with higher dose of probiotic strains serum triglycerides level decreased. Total antioxidant status in groups with addition of probiotic strains showed higher values in comparison to control group. Serum albumin level was found to increase after consumption of probiotic preparation in group with higher dose of probiotic strains. Probiotic strains improved body weight in last observed weeks of feeding.     

我国机械制造技术的现状及发展趋势

机械制造技术是发展机械制造业的关键技术,是创造财富和为科学技术发展提供先进手段的基础。文章对我国机械制造技术的特点、现状及今后的发展趋势作了一些浅显的分析。