Correlation of Soil pH and Mehlich‐3 Phosphorus with Postflood Rice Phosphorus Concentrations in Arkansas

Abstract

Plant‐available phosphorus (P) measured by routine soil‐test methods is poorly correlated with rice grain yield in Arkansas. Our objective was to determine whether soil water pH (pH_w) and Mehlich‐3 P were correlated with growth and yield of rice grown on silt loam soils. Data from 35 field studies were used to correlate Mehlich‐3 P and pH_w with relative yield, dry matter accumulation, and P concentration at the midtillering stage. Significant linear or nonlinear relationships between pH_w or Mehlich‐3 P with rice growth parameters were delineated but explained less than 27% of the variability in dry matter and P concentrations at the midtillering stage and grain yield at maturity. Mehlich‐3 P and pH_w together explained 61% of the variability in midtillering P concentrations. Midtillering whole‐plant P concentrations were positively related to relative grain yield and dry matter production and will be used to identify soils with limited P availability for rice in Arkansas.     

产单核细胞李斯特菌P60蛋白的可溶性表达

以食品中分离到的L.mXFL0605株为试验菌株,PCR扩增得到iap全基因。将iap连接到pET-28a(+)载体进行原核表达,分别采用培养温度为25℃或37℃,IPTG浓度为5μg/mL或10μg/mL优化组合进行诱导。结果显示,当采用37℃培养和10μg/mLIPTG诱导时可以获得部分可溶性表达的p60,重组p60蛋白分子质量约60 ku。     

Effects of stocking density and algal concentration on the survival,growth and metamorphosis of Bobu Ivory shell,Babylonia formosae habei (Neogastropoda: Buccinidae) larvae

Independent and combined effects of stocking density and algal concentration on the survival, growth and metamorphosis of the Bobu Ivory shell Babylonia formosae habei larvae were assessed using a 5 × 5 factorial design with densities of 0.25, 0.5, 0.75, 1.00 and 1.50 larvae mL⁻¹ and algal concentrations of 5, 10, 15, 20 and 25 × 10⁴ cells mL⁻¹ in the laboratory. Larval growth, survival and metamorphosis were significantly affected by both the independent effects of stocking density and algal concentration and by their interaction. The highest per cent survival (72.5%) and metamorphosis (49.5%), fastest growth (41.57 μm day⁻¹) and shortest time to initial metamorphosis (10 days) all occurred at the lowest stocking density and the highest algal concentration. Both crowding and food limitation had independently negative impacts on the survival, growth and metamorphosis of larvae, and these negative impacts were further strengthened by the interaction of a higher stocking density and a lower algal concentration. Moreover, the results suggest that stocking density and algal concentration obviously played different roles in determining larval survival and growth. To maximize survival and growth, B. formosae habei larvae should be reared at a lower stoking density of 0.25 larvae mL⁻¹ and fed a higher algal concentration of 25 × 10⁴ cells mL⁻¹ in large-scale hatchery seed culture.     

高钙饲粮对青年蛋鸡血清一氧化氮浓度和抗氧化功能的影响

本试验旨在研究高钙饲粮对青年蛋鸡血清一氧化氮（ＮＯ）浓度和抗氧化功能的影响。将 ３５日龄 １００羽伊沙蛋鸡随机均分为对照组（含钙 １．００％）和高钙组（含钙 ３．７８％），每组 ５个重复，每个重复 １０羽。每天观察鸡的精神状态、食欲和粪便情况。在饲喂高钙饲粮第 ０、８、１６、２４和 ３２天时，分别测定 ２组鸡的血清中 ＮＯ浓度和丙二醛含量及抗氧化酶系统的变化。结果表明：１）高钙饲粮能引起青年蛋鸡长期腹泻，在饲喂高钙饲粮的第 ８天就发生高血钙症。２）与对照组相比，高钙组在饲喂高钙饲粮第 ８天和第 １６天血清 ＮＯ浓度无显著变化（Ｐ＞０．０５），第２４天和第 ３２天显著升高（Ｐ＜０．０５）；第 ８天和第 ２４天血清超氧化物歧化酶活性、总抗氧化能力无显著变化（Ｐ＞０．０５），第 １６天显著升高（Ｐ＜０．０５），第 ３２天显著降低（Ｐ＜０．０５）；第 ８、１６、２４天血清丙二醛含量无显著变化（Ｐ＞０．０５），第 ３２天显著升高（Ｐ＜０．０５）；第 ２４天和第 ３２天黄嘌呤氧化酶活性有升高趋势（Ｐ＞０．０５）。结果提示，饲喂高钙饲粮可导致青年蛋鸡发生长期腹泻，引起高血钙症，导致其机体内自由基的产生与清除的动态平衡遭到破坏，使自由基的产生远远超出清除能力。     

贵州省黔南州森林环境氧气含量分析

在对黔南州林区氧气含量进行实测基础上,运用科学的分析方法,全面评价了黔南州林区森林释氧功能及其对空气质量状况的改善。研究表明:黔南州森林环境空气中氧气平均含量为21.19%,超出正常空气中氧气浓度0.24%,氧气浓度最高的达到21.54%,超出正常水平0.59个百分点;森林公园中的氧含量明显高于其他森林环境,平均值高达21.32%,超出正常水平0.37个百分点;针阔混交林空气中氧气浓度最高,为21.26%,其次是针叶林,氧气含量最低的是阔叶林;森林环境中的氧气浓度随着林龄的增长而增加,林木成熟后,氧气浓度随着树木年龄的增长而逐渐下降。     

Needle Collection Time for Nutrient Evaluation in Christmas Tree Production

Christmas tree needle sampling to evaluate nutrient need is an established practice. Data to support the recommended fall sampling time in Oregon and Washington were not found. In addition, the recommendation for needle sampling of Fraser fir in North Carolina was made without data from winter months. The goal for this article is to affirm or modify recommended needle sampling time. Needles of Douglas fir, Turkish fir, Nordmann fir, Noble fir, Grand fir, and Fraser fir Christmas trees were collected monthly for a year, dried, and analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and boron (B). No single period was found for any species when needle nutrient concentration was stable for all elements determined. Needle collection time was chosen by integrating cultural practices, likelihood of nutrient deficiency, and needle nutrient concentration changes for species grown in an area. Needle collection is recommended during February in western Oregon and Washington. The current sampling time, fall, is logical for Fraser fir Christmas tree production in North Carolina.     

Tyrosine Ameliorates Some of the Clinical,Biochemical and Haematological Effects of Acute Stress Associated with Transportation of Desert Sheep

We studied some clinical, biochemical and haematological variables in Desert (Najdi) sheep acutely stressed in the course of individual road transportation, and the influence thereon of pretreatment with tyrosine. Transportation for 30 min resulted in variable but statistically insignificant increases in heart, pulse and respiratory rates. It also caused significant increases in the plasma concentration of cortisol (from 43.5 to 101.7 mmol/L) and glucose (from 3.1 to 4.5 mmol/L), and a decrease in that of magnesium (from 0.85 to 0.72 mmol/L). The endogenous thiocyanate level was unaffected. The transportation stress also decreased the haematocrit (PCV) and the number of lymphocytes, and increased the concentration of haemoglobin. Pretreatment of sheep with tyrosine at a dose of 100 mg/kg by the intravenous route significantly ameliorated the stress-induced clinical, biochemical and haematological changes. The treatment caused no overt adverse effects.     

14种农药的非致死浓度对拟长毛钝绥螨繁殖和定居的影响

在室内测试了１４种农药对拟长钝缓螨的非致死浓度及其对定居和繁殖的影响。氯氰菊酯，粉锈宁，克螨特，三氯杀螨醇对拟长毛钝绥螨的繁殖，叶上定居及着卵量都有很大的影响。氧化乐果影响拟长毛钝绥螨的繁殖，对定居影响不大。天王星，高效灭百可，灭扫利，功夫不影响，镇量影响在植侏上定居和叶上着卵量。双甲脒，卡死克，阿波罗对拟长毛钝绥螨影响不显著。爱力螨克和尼索朗对拟长毛钝缓螨的繁殖，定居，着卵量均不良的影响。     

蛋用型鸡血浆极低密度脂蛋白浓度,肥度,生产性能之间的相关研究

以褐壳蛋鸡祖代母本种鸡为研究材料，用比浊法测定血浆极低密度脂蛋白浓度。试验结果表明，母鸡８１周龄腹脂重，腹脂率，鲜肝脂肪含量的变异系数分别高达４７％，３９％，４７％。表明这些性状在鸡群中未做过选择。血浆ＶＬＤＬ浓度与腹脂重，腹脂度，肝重，肝脂含量均呈正表型相关趋势。