Volatile fatty acid profile for grass hay or alfalfa hay fed to alpacas (Vicugna pacos)

The purpose of this study was to determine the diurnal composition and concentration of volatile fatty acids (VFA) and to determine VFA composition and concentration differences between stomach compartment 1 (C1) and caecum of alpacas fed grass and alfalfa hay. The study was divided into two experiments. In Experiment 1 (EXP 1), 10 male alpacas (3+ years old, 65 kg BW) were divided into two groups, housed in drylot pens, provided ad libitum water and fed alfalfa (AH) or grass hay (GH) for 30 days. The alpacas were slaughtered and the digestive tract collected, divided into sub‐tract sections, weighed and digesta sampled for pH, dry matter (DM) and NDF. Volatile fatty acid composition and concentration were determined on C1 and caecal material. Four adult male (3+ years old, 60 kg BW), C1 fistulated alpacas were housed in metabolism crates and divided into two forage groups for Experiment 2 (EXP 2). Alpacas were fed the forages as in EXP 1. Diurnal C1 VFA samples were drawn at 1, 3, 6, 9, 12, 18 and 24 h post‐feeding. There were no differences between forages for tract weight, C1 and caecum digesta DM or NDF. Differences were noted (p < 0.05) for pH between forages and sub‐tract site. Volatile fatty acids concentrations were different (p < 0.05) for forage and site, and total VFA was higher for AH than GH (110.6 and 79.1 mm ) and C1 than caecum (40.7 and 27.6 mm ). Proportion of VFA was significant (p < 0.05) for forage and site, C1 acetate highest for GH (84.8 vs. 74.0 mm ) and caecum acetate 83.7 and 76.2 mm for GH and AH respectively. These data demonstrate the level of VFA produced in C1 and the caecum of alpacas and the diurnal VFA patterns. Composition of VFA is similar to other ruminant species.     

Diurnal variations in hypothalamic monoamine levels in the teleostChanna punctatus (bloch) in response to melatonin under two photothermal conditions

Hypothalamic dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) levels exhibited marked day-night variations under ambient photoperiod and temperature (12L12D; 17±1°C) with peak values at mid-light phase. The 16L8D; 22±1°C treatment reversed the diurnal rhythm of 5-HT, but not that of DA and NA. However, there was an overall increase in the levels of the catecholamines on exposure to the long photoperiod and high temperature. The administration of melatonin in the fish held on 16L8D; 22±1°C regime restored the 5-HT rhythm to that of the 12L12D; 17±1°C control group, but with elevated mid-photophase value. However, there was no effect of the indole treatment on the 5-HT rhythm under the 12L12D; 17±1°C regime. Melatonin causes a significant reduction of NA level in both the groups, while DA level did not change in either group.     

苏州主要园林树种的光合固碳能力对比分析

园林树种的光合固碳能够维持城市空气中CO2和O2的平衡。以苏州地区32个园林树种为材料,利用Li-6400便携式光合作用仪测定了其光合日变化,并利用测定结果计算其日净固碳能力,再以聚类分析法对其日净固碳量进行分类。结果如下:第1类[日净固碳量极高,17.55~18.76 g/(m2·d)]有紫荆、枫杨、垂柳,第2类[日净固碳量高,12.25~16.02 g/(m2·d)]有大叶女贞、乌桕、榉树、枫香树、垂丝海棠、樱花、夹竹桃,第3类[日净固碳量中等,8.57~11.97 g/(m2·d)]有银杏、红花檵木、朴树、乐昌含笑、红叶李、杜英、海桐、金边黄杨、杜鹃、重阳木、樟树、金丝桃、红叶石楠,第4类[日净固碳量低,3.81~7.64 g/(m2·d)]有红枫、洒金东瀛珊瑚、金叶女贞、八角金盘、五角枫、鹅掌楸、紫薇、木芙蓉、桂花。上述分析结果可对苏州的园林规划及树种选择提供一定的理论指导。     

青藏高原高寒牧区冷季补饲藏系绵羊温室气体排放特征

为了揭示藏系绵羊温室气体排放特征,在青藏高原高寒牧区采用密封式呼吸箱-气相色谱结合的方法,于2013年冷季对3只身体健康、均重(50.13±1.28)kg的藏系绵羊温室气体(CH4、CO2、N2O)日排放特征进行了研究。试验期间,动物日粮的精料为蒸煮饲料,粗粮为青干草饼。结果表明,藏系绵羊的CH4排放日动态具有明显规律性,排放峰值在8:00和17:00(P0.01),排放峰值的出现时间与饲喂时间基本吻合,最小值出现在次日7:00;CO2的日排放曲线相对平稳;N2O的日变化没有明显规律且排放量极低。在冷季补饲模式下,藏系绵羊的CH4、CO2和N2O日排放量分别为(16.17±1.27)、(549.18±20.63)g·head-1和(0.73±0.32)mg·head-1。     

油料植物红皮糙果茶与油茶叶片光合特性研究

为探明油料植物红皮糙果茶（Camellia crapnelliana Tutcher）光合作用日变化体征,为其科学栽培提供理论依据, 采用Licor-6400便携式光合作用测定仪测定红皮糙果茶和油茶（Camellia oleifera L.）的光合生理特性及环境因子的日变化,并进行分析研究。结果表明,在晴天条件下红皮糙果茶净光合速率曲线呈双峰状,自9:10至13:10期间有一个长达4 h的高效光合平台期（19.7～20.2 μmol·m^-2·s^-1）,最大值为20.2 μmol·m^-2·s^-1。气孔导度日变化与油茶相似呈单峰曲线于13:10达到峰值0.22 mmol·m^-2·s^-1,但其蒸腾速率整体高于油茶。油茶无明显光合“午休”现象,净光合速率最大值出现在中午11:10,为20.1 μmol·m^-2·s^-1。相比之下红皮糙果茶光合作用时间较长,总光合产率较高。     

棉花渗透调节与蒸腾速率的日变化关系

大田正常供水条件下，随１ｄ内光照和温度增加，棉花叶水势及渗透势下降，最低水势为－１１．４巴，渗透势为－１４．２巴，其膨压值为２．８巴，表现出渗透调节作用。气孔导度在中午一段时间最高，而蒸腾速率最高点在１２∶００时，之后下降，表明水分胁迫下产生渗透调节作用，使叶片保水力增加，蒸腾减弱。Ｋ＋和可溶性糖变化，以渗透势下降最低时积累最多，是棉花干旱时主要的渗透调节物质。     

Diurnal Macronutrients Uptake Patterns by Lettuce Roots under Various Light and Temperature Levels

In order to reduce nutrient wastes to the environment the supply should be in accordance to the demand for these. Two experiments were conducted to study and quantify the effect of temperature, irradiance, and plant age on the uptake of nitrate (NO₃^?), ammonium (NH₄⁺), dihydrogen phosphate ion (H₂PO₄^?), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), and sulfate (SO₄²). In the first experiment, various levels of temperature and irradiance were applied to plants in a growth chamber, while in the second experiment the uptake was studied along the crop season under greenhouse conditions. The uptake rates were calculated at 2-hour intervals through sampling the nutrient solution and analyzing it by inductively coupled plasma atomic emission spectrometry (ICP-AES). Increasing light and temperature enhance the uptake rates, while the rates decrease with plant age. Nitrogen absorption was similar during the day as during the night. No differences were found in the absorption of H₂PO₄^?, K⁺, Ca²⁺, Mg²⁺, and SO₄^2? between day and night. Nitrate absorption was found to have a positive correlation with the absorption of all the ions except for NH₄⁺.     

间作模式下桑树与大豆叶片的光合日变化特点

为了提高桑树与大豆间作模式下地上部分的光能利用率,优化桑树与大豆复合经营的空间配置,研究了在这一间作模式下生育后期速生桑树和大豆叶片的光合日变化特点.结果表明:无论在单作还是间作模式下大豆叶片在13:00时均表现出明显的光合"午休"现象,其光合性能并未因间作桑树而受到影响;一天之中,桑树叶片分别在9:00时和13:00时出现光抑制现象,并且13:00时光抑制的程度和持续的时间均大于9:00时出现的,不同种植模式下桑树叶片的光合日变化情况存在着明显的差异,一天之中,间作模式下桑树叶片的P_r、_r、和F_v /F_m等光合指标值均优于单作模式的桑树叶片,桑树与大豆间作具有一定程度的种间促进作用,1年生桑树幼苗与大豆间作能明显提高生育后期速生桑树叶片的光合生产能力,从而可实现高产的目的.     

湿地松半同胞家系净光合速率日变异规律研究

 使用LI-6400便携式光合测定系统,对湿地松优良半同胞家系净光合速率的日变异规律进行了研究,结果表明1年中湿地松各半同胞家系3~8月典型天气的Pn值日变化模式为‘双峰’型,其余各月即1、2、9、10、11、12月的Pn值日变化模式为‘单峰’型,各家系1龄针叶的Pn值显著高于2龄针叶的Pn值,全天以傍晚时的Pn值为最低。湿地松优良半同胞家系的Pn值显著高于普通种的Pn值,表明通过遗传改良,提高了湿地松的光合能力,从而提高了湿地松良种的生长量和产量。