陕西省日照时数季节变化特征分析

利用1961-2010年陕西省95个气象站点的观测数据,采用Mann-Kendal非参数检验方法和EOF经验正交分解法,对陕西省近50 a来四季日照时数的变化特征进行了趋势性分析.结果表明,50 a来,陕西省日照时数的下降出现在夏季和冬季,其中夏季减少趋势通过了p=0.01的显著性检验.春季和秋季变化表现为上升趋势,但上升趋势不明显;四季日照时数的主要下降中心在延安地区中部和宝鸡地区西部,不同季节气候变异中心的位置会发生变化.     

杂交条纹鲈苗种小水泥池培育技术试验

用地上露天小水泥池8个．进行杂交条纹鲈苗种培育试验．放养313龄水花30000尾．通过天然饵料、藻粉投喂以及适当水质管理措施．经32天培育，共培育3．5～4．6cm体长的鱼种4336尾．最高成活率为19．1％，最低为6％，平均为14．5％。     

大口黑鲈对饲料中丁基羟基茴香醚的耐受性评价

本试验旨在通过生长性能、血浆生化指标、组织抗氧化指标及肝脏、肠道组织学变化,评价大口黑鲈对饲料中丁基羟基茴香醚(BHA)的耐受性。以初始体重为(6.20±0.01)g的大口黑鲈为靶动物,在基础饲料中依次添加0(D0组,作为对照组)、150(D150组)、300(D300组)和1 500 mg/kg(D1500组)的BHA,其中300和1 500 mg/kg分别是最高推荐剂量(150 mg/kg)的2和10倍,进行为期10周的饲喂试验。每组6个重复,每个重复30尾鱼。结果表明:4组中以D150组的生长性能最好,其余各组的终末均重、特定生长率、增重率和摄食量无显著差异(P0.05)。各组肥满度、脏体比和肝体比无显著差异(P0.05)。对照组血浆中总胆固醇、甘油三酯含量及碱性磷酸酶活性显著高于其余各组(P0.05)。D150和D300组血浆中高密度脂蛋白胆固醇/总胆固醇显著高于对照和D1500组(P0.05)。D1500组血浆中谷草转氨酶、谷丙转氨酶活性显著低于对照组(P0.05),与D150、D300组无显著差异(P0.05)。D150和D300组肝脏中超氧化物歧化酶活性显著低于对照组(P0.05),与D1500组无显著差异(P0.05)。饲料中添加1 500 mg/kg BHA可以显著提高肝脏中总抗氧化能力(P0.05);饲料中添加150、300、1 500 mg/kg BHA均显著降低了血浆、心脏和肝脏中丙二醛的含量(P0.05)。对照、D150和D1500组大口黑鲈的肝脏、肠道都有不同程度的损伤,但D150和D1500组的损伤相对较少。上述结果表明,饲料中添加150 mg/kg BHA对大口黑鲈具有一定的脂肪代谢促进作用和抗氧化保护功能,且对大口黑鲈是安全的,安全系数为10倍。     

Effects of conventional and organic feed on the mineral composition of cultured European sea bass (Dicentrarchus labrax)

European sea bass (Dicentrarchus labrax) is a widely consumed marine fish in Mediterranean areas, and different farming techniques are applied for fish culturing to satisfy the growing demand for seafood. The aim of this study was to investigate the effects of conventional and organic feed on the quality of cultured European sea bass (Dicentrarchus labrax) collected during the growth period. The concentrations of ash, moisture, essential macro‐elements (Ca, K, Mg, Na and P), micro‐elements (Co, Cr, Cu, Fe, Mn, Ni and Zn) and toxic elements (As, Cd, and Pb) were determined in feeds and in fillets of cultured fish. The results were compared to those obtained from wild sea bass. Results showed that the differences between organic diet‐fed and conventional diet‐fed sea basses varied in relation to the specific element measured and the growth period. The former showed higher concentration of Fe, Mg and Cr, and lower Na content. The amount of P, Na, Fe, Cu and Cr in wild sea bass was significantly (P ≤ 0.05) higher than that found in farmed fish. The levels of toxic elements in cultured sea bass were always within the allowed limit for fishery products. Wild samples had significantly (P ≤ 0.05) higher content of arsenic and lead than farmed sea bass. Cultured fish represent a valuable dietary source of essential macro‐ and micro‐elements. Controlled rearing systems and feedings were related to a decrease in the presence of some toxic metals in cultured fish compared with wild fish.     

Influence of partial substitution of dietary fish oil by vegetable oils on the metabolism of [1-14C] 18:3n-3 in isolated hepatocytes of European sea bass (Dicentrarchus labrax L.)

The static or declining supply of fish oil from industrial fisheries demands the search of alternatives, such as plant (vegetable) oils, for diets in expanding marine aquaculture. Vegetable oils are rich in C₁₈ polyunsaturated fatty acids but devoid of the n-3 highly unsaturated fatty acids in fish oils. Previous studies, primarily with salmonids, have shown that including vegetable oils in their diets increased hepatocyte fatty acid desaturation. In the present study, we have investigated the effects of dietary partial substitution of fish oil (FO) with rapeseed oil (RO), linseed oil (LO) and olive oil (OO) on the desaturation /elongation and, -oxidation capacities of [1-¹⁴C]18:3n-3 in isolated hepatocytes from European sea bass (Dicentrarchus labrax L.), in a simultaneous combined assay. Fish were fed during 34 weeks with diets containing 100% FO, or RO, LO and OO, each included at 60% with the balance being met by FO, with no detrimental effect upon growth or survival. The highest total desaturation rates were found in hepatocytes of fish fed FO diet (0.52±0.08 pmol/h/mg protein) and OO diet (0.43±0.09 pmol/h/mg protein), which represented 3.2% and 2.7% of total [1-¹⁴C]18:3n-3 incorporated, respectively. In contrast, lowest desaturation rates were presented by hepatocytes of fish fed LO and RO diets (0.23±0.06 and 0.14±0.05 pmol/h/mg protein, respectively) represented 1.4% and 0.9% of total [1-¹⁴C]18:3n-3 incorporated, respectively. The rates of [1-¹⁴C]18:3n-3 β-oxidized were between 11-fold and 35-fold higher than desaturation. However, no significant differences were observed among β-oxidation activities in hepatocytes of fish fed any of the diets. The present study demonstrated that the European sea bass, as a carnivorous marine fish, presented a ‘marine’ fish pattern in the metabolism of 18:3n-3 to 20:5n-3 and 22:6n-3. This species appeared to have all the enzymic activities necessary to produce 22:6n-3 but presented only extremely low rates of fatty acid bioconversion. Furthermore, nutritional regulation of hepatocyte fatty acid desaturation was minimal, and dietary vegetable oils did not increase desaturase activities, and in RO and LO treatments the activity was significantly lower. This revised version was published online in July 2006 with corrections to the Cover Date.     

播期对鄂中北地区不同类型粳稻产量、生育期及温光利用的影响

为了明确鄂中北地区稻麦周年轮作模式下,播期对不同类型粳稻生育期、产量及其构成因素、温光资源利用的影响,以常规早熟中粳、中熟中粳、迟熟中粳、籼粳杂交早熟中粳和籼粳杂交中熟中粳为材料,在湖北省襄阳市农业科学院团山试验基地进行试验。结果表明,随着播期推迟,各类型粳稻生育期均显著缩短,迟熟中粳缩短幅度最大,籼粳杂交早熟中粳缩短幅度最小。各类型粳稻营养生长阶段受温光影响较大,而生殖生长阶段相对稳定;随着播期推迟,各类型粳稻全生育期有效积温及其利用率显著降低,日照时数利用率呈减少趋势。同一播期内,籼粳杂交中粳热量利用率高于常规中粳;各类型粳稻产量均以第Ⅰ播期最高,第Ⅴ播期最低,产量下降的主要原因是每穗颖花数和结实率显著降低。鄂中北地区粳麦周年轮作模式下,粳稻应首选籼粳杂交中熟中粳和常规迟熟中粳,其次是籼粳杂交早熟中粳。籼粳杂交中熟中粳和常规迟熟中粳的最佳播期为5月9日-5月15日。     

Effects of addition of a bird repellent to fish diets on their growth and bioaccumulation

The effects of adding the nonlethal bird repellent methyl anthranilate (MA), at levels of 100 and 1000 mg kg^?1, to fish feed on the bioaccumulation and growth of juvenile (10 g) hybrid striped bass (Morone chrysops×M. saxatilis) and juvenile (1 g) African cichlid fish Aulonocara jacobfreibergi were investigated under laboratory conditions. The bird repellent did not have any effect on the fish growth or survival over a period of 6 weeks. MA residues at low levels of 11.2±2.6 μg g^?1 were found in lipophilic tissues (liver) of MA‐fed fish. Control fish, which had no MA added to their diet, had a much lower level of 0.6±0.3 μg g^?1 MA in their liver. Fish muscle was found to contain negligible MA residues, while the outer body surface mucus did not contain any MA. Following a 6‐week depuration period, during which the previously MA‐fed hybrid striped bass were fed a feed to which no MA was added, the levels of MA residues detected were reduced by one order of magnitude.     

近50年青海高原生长季日照时数的变化特征

为了了解近50年青海高原生长季日照时数的分布规律和变化趋势及其变化原因,选用青海高原43个气象站的基本气象数据,分析整个区域和4个生态功能区生长季日照时数在过去50年中的变化趋势和变化成因。结果表明：青海高原整个区域和柴达木盆地生长季日照时数呈显著减少趋势,其他3个生态功能区变化趋势不明显。空间分布为从西北部向东南部逐渐减小。变化趋势存在较大的空间差异性。整个区域和柴达木盆地日照时数突变时间分别为2004年和1999年,环青海湖地区、东部农业区和三江源地区在2006—2008年之间发生突变。影响青海高原整个区域和生态功能区生长季日照时数的主要因子是云量,而次要因子表现略有不同。生长季日照时数的分布随着经度和海拔高度的增加而减少,随着纬度的增加而增加,经度的影响最大。     

起伏地形下地理可照时数空间分异分析——以重庆市为例

基于重庆市100 m×100 m分辨率的数字高程模型,利用Solar Analyst模型对各月份地理可照时数进行了模拟,并通过空间叠加运算进一步求得了季、年地理可照时数。季节和月地理可照时数变化表明重庆市夏季地理可照时数最长,以6月最高;冬季地理可照时数最小,以12月最低,地形遮蔽对可照时数的影响显著,可明显影响可照时数的局地空间分布。结合坡度、坡向因子,对起伏地形条件下地理可照时数模拟结果进行了时空分布特征分析。分析结果表明:同坡度不同坡向的地理可照时数都随着太阳高度角的增大而增加;同坡向的地理可照时数随着坡度的增加而减小;坡度越高地理可照时数受坡向影响程度越大。