Growth and survival of Atlantic salmon, Salmo salar L., fed different dietary levels of astaxanthin. First-feeding fry

Atlantic salmon fry hatched from pigment-free eggs and from eggs containing the pigment astaxanthin were fed eleven casein/gelatine-based purified diets with varying levels of astaxanthin, ranging from 0 to 317 mg kg^?1, to determine the optimum dietary astaxanthin level for satisfactory growth and survival during the start-feeding period. The fish were fed the experimental diets for a period of 11 weeks. No difference in performance was found between the two types of fry originating from the pigment-free eggs and those containing pigment. However, the dietary astaxanthin concentration was found to have a significant effect on both the growth and the survival of fry. Fish fed diets with astaxanthin concentrations below 5.3 mg kg^?1 were found to have marginal growth. In addition, mortality was high in the groups fed diets with astaxanthin concentrations below 1.0 mg kg^?1. The specific growth rate (SGR) was also affected by the dietary treatment. The lipid content was higher and the moisture content was lower in the fish fed the diets containing astaxanthin concentrations above 5.3 mg kg^?1. The vitamin A and astaxanthin concentrations in whole-body samples of the fry were significantly affected by the dietary level of astaxanthin. A plateau level in whole-body vitamin A concentration was observed at dietary levels of approximately 80 mg astaxanthin kg^?1 and higher, while no maximum astaxanthin concentration in whole-body samples was observed within the dietary levels used. The results suggest the need for a minimum dietary astaxanthin concentration of 5.1 mg kg^?1 to achieve maximum growth and survival during the start-feeding period. The results indicate a low bioavailability of vitamin A palmitate and acetate and the results also suggest a provitamin A function for astaxanthin during the same period.     

宁波市鄞州区农作物农药残留现状与控制对策

对鄞州区种植的稻谷、叶菜类、水果类、豆类、茄果类和块茎类农产品按月进行了411个批次抽样,按照国家相关规定对22个农药项目进行了检测。检测结果发现样本农药项目检出率为0.3%,农产品农药残留合格率97.82%,农药残留检出项目中88.89%是杀虫剂。超出农药残留标准的样本主要是5—10月的青菜,叶菜类超标样本率达到3.72%。农药残留超标样本在平原、滨海地区种植散户中有发现,而在山区各规模农户中均有发现。小学文化程度农户样本农药残留超标率高达4.50%,是大学文化程度农户样本农药残留超标率的6.16倍。为了降低鄞州区农作物农药残留率,提出5方面的控制对策。     

不同坡位杉木林土壤碳储量研究

通过实地调查取样和室内实验测定,比较了上坡和下坡杉木的土壤碳库及其垂直分布差异,研究了坡位对杉木人工林固碳功能的影响。结果表明,杉木上坡和下坡的枯枝落叶层有机碳贮量分别为0.9和1.1t/hm2,坡下的枯枝落叶层有机碳贮量较坡上高出32%。坡上和坡下的土壤有机碳贮量分别为149.9和174.2t/hm2,且表层(0-40cm)碳贮量分别占整个碳贮量(0-100cm)的55%和56%。上坡和下坡的土壤有机碳含量和贮量随土层深度的加深而递减,各土层的有机碳含量和贮量均表现为下坡高于上坡。     

山葡萄种内杂交后代浆果色素、单宁和总酸含量的遗传分析

测定了山葡萄种内6个杂交组合888株杂交后代实生苗浆果的总酸、单宁和果皮色素(色价)的含量并对其进行了遗传分析。果实总酸含量主要受双亲遗传因素的影响，趋向高酸亲本；杂种后代果皮色素(色价)群体表现为趋中变异，但也受杂交亲本相互影响；单宁平均含量均都比高单宁亲本高，表现为超亲遗传。     

林地调查中的面积单元线性测量法（SL法）

林业调查中采用的基本方法是全林调查法和局部估测法，而局部估测方法中最常用的是角规测量法与标准地法，在林地调查中角规法误差较大，而标准地法又存在着难于布设的问题。本研究提出的面积单元线性测量法，可方便快捷地进行局部估测，节省人力和时间，同时又达到了较高的精度，特别适用于不规则林分的调查。     

山区高油玉米高产优质栽培模式研究

为探索在黔西北山区种植高油玉米高产优质的栽培模式，促进山区种植业结构调整，采用多元二次正交回归旋转组合设计，研究了高油玉米产量、产油量与四个主要栽培因子——种植密度及N、P、K肥施用量之间的关系，建立了数学模型，解析了各因素对产量、产油量的效应，通过计算机模拟寻优，筛选出了黔西北山区高油玉米高产优质的农艺综合方案：密度62463～63710株/ hm2；N肥（纯N）321.79～359.04kg/hm2；P肥（P2O5）319.94～345.32 kg/hm2；K肥（K2O）293.64～333.30 kg/hm2。