Quantitative Dietary Taurine Requirement for California Yellowtail,Seriola lalandi

Although taurine has been identified as a required nutrient in several Seriola species, there are no available quantitative data on dietary taurine requirements for these commercially important species and recommendations are highly variable. Therefore, juvenile Seriola lalandi were fed one of eight practical diets supplemented with graded levels of taurine (0.11–1.08% of the dry diet, analyzed) to estimate their taurine requirement. Response in growth rate, feed efficiency, and nutrient deposition were evaluated using a broken‐quadratic model and 4‐ and 5‐parameter saturation kinetic models (4‐SKM and 5‐SKM) Blood serum composition was analyzed using linear models. Requirement estimates based on growth rates (thermal‐unit growth coefficient) and protein deposition were similar at 0.26% (95% confidence interval [CI]: 0.23–0.28) and 0.29% (95% CI: 0.25–0.34) dietary taurine, respectively. Feed and protein deposition efficiencies were optimized at 0.26–1.02% and 0.26–1.00% dietary taurine, respectively. Taurine deposition in the animal was maximized at higher dietary levels (0.64%). Levels of serum taurine increased in response to dietary levels and peaked at around 0.80% dietary taurine. Concomitantly, serum urea and total amino acid levels decreased with increasing dietary taurine levels, suggesting a reduced amino acid catabolism relative to the aforementioned improvement in protein deposition efficiency.     

Multiple effects of grape seed polyphenolics to prevent metabolic diseases

Obesity is increasing in developing countries. Population studies show a relationship between affluence and obesity. Changing food intake patterns with affluence such as preference for foods with less astringent polyphenolic compounds and dietary fibers may increase risk of metabolic dysfunctions due to caloric imbalance. Animal models of obesity consistently show that grape seed procyanidins prevent increases in body and abdo- minal adipose weight gain, plasma cholesterol, liver weight gain and inflammation in animals on high fat diets. The mechanisms are not clear because the oral intake of procyanidins results in pleiotropic interactions with proteins in the mouth, stomach, small intestine, cecum and colon that affect the rate of digestion of bioavailability of macronutrients, sterols, and dietary fiber. Procyanidins also bind bile acids and reduce intestinal permeability to inflammatory bacterial cell wall fragment. Procyanidins are not degraded or metabolized until reaching the lower gut where they can be metabolized into phenolic acids by gut bacteria. While they are metabolized by gut bacteria, they also alter total numbers and distribution of phyla and species of gut bacteria. Gut bacteria are recognized as significant contributors to obesity and obesity related metabolic diseases. The review examines the different pleiotropic effects of grape seed procyanidins that have a significant effect on metabolic disease in animal models of obesity.     

菌根真菌接种对盆栽杜鹃花生长的影响

为了研究菌根真菌接种对盆栽杜鹃花生长的影响,以 2 个杜鹃花品种为材料,开展了 3 个菌株在有机肥和无机肥施肥组中的菌根真菌接种实验。结果表明,未接种菌根真菌的盆栽杜鹃花菌根侵染率较低（5%~7%）,接种的盆栽杜鹃花菌根侵染率提高至 12%~20%;2 个品种的接种植株在株高、地径、总分枝数和叶面积上均有显著增加,其中树粉孢属真菌菌株接种和施用无机缓释肥的组合处理盆栽杜鹃花生长量最大。     

氮肥运筹对郑单1002和郑单958冠层特征和产量的影响

以郑单1002和郑单958为材料,0(N0)、150(N1)、300(N2)kg/hm2氮肥水平,常规尿素和一次性基施掺混控释肥两种氮肥类型,研究不同氮肥运筹对夏玉米冠层特征、干物质积累与分配和产量的影响。结果表明,增加施氮量,两个品种穗位层和近地表叶面积指数(LAI)比N0处理增加25.7%~52.5%,开花期和成熟期干物质积累、千粒重、穗粒数、穗长和产量显著增加,农学利用效率降低22.0%~40.0%。与常规尿素相比,掺混控释肥增加玉米生长后期穗位层和近地表的透光率和成熟期干物质积累,提高了千粒重、穗粒数、产量和氮肥农学效率,降低子粒含水率。在相同施肥条件下,与郑单958相比,郑单1002的LAI和穗粒数分别提高7.5%~14.8%和2.3%~11.5%,千粒重降低1.4%~6.2%,产量提高0.8%~6.2%。     

Genotype x environment interactions and optimum resource allocation for sugarcane yield trials in Swaziland

To account for genotype x environment (G x E) interactions, sugarcane varieties are tested in multi-environment trials (METs) across multiple crop-years and seasons (early vs. late) under fully irrigated conditions in Swaziland. This study aimed to quantify the main sources of variation relevant to the MET network, identify mega-environments, evaluate adaptability of imported sugarcane varieties, and optimize resource use within the testing network. Nine varieties (eight imported Mauritian and one South African variety) were tested at two sites (Mhlume – M and Simunye – S), harvested early (E) and late (L) in the season across five crop-years in replicated (8) Latin square designs. A linear mixed model analysis of cane yield (tons of cane per ha; TCH), sucrose content (SUC%), sucrose yield (tons of sugar per ha; TSH), and fiber content (FIB%) showed that variety x season interactions were highly significant (P < 0.001) and larger than variety x site interactions for most traits. Genotype + genotype x environment (GGE) biplots revealed clustering of environments into two mega-environments by season rather than by site. Two Mauritian varieties were superior in each of the early and late mega-environments. Broad-sense heritability (H²) for all traits was larger than 0.79, with the highest value observed for FIB% (0.89). Resource optimization analysis, using variance components, suggested that future testing be conducted at a single site, across two seasons, with replicate numbers >5, and harvested across approximately five crop-years. Strong variety x season interactions should be exploited more aggressively in irrigated sugarcane selection programs.     

甘蓝型油菜株高及其相关性状的主基因+多基因遗传分析

油菜株高对产量、抗逆性尤其是抗倒伏性有重要影响,适当降低株高可提高油菜抗性和收获指数进而提高产量。甘蓝型油菜(Brassica napus L.)矮秆自交系‘74-1002’具有早熟、分枝多、抗倒伏等优良性状,是进行油菜株高遗传和矮化育种的良好材料。以高秆甘蓝型油菜自交系‘HN92’为母本,‘74-1002’为父本,杂交构建6世代遗传群体(P1、P2、F1、F2、B1和B2),对6世代群体的株高及其相关性状进行度量,采用主基因+多基因混合遗传模型进行遗传分析。结果表明:株高(PH)、主花序长度(MIL)及一次有效分枝高度(VBH)均受到2对加性主基因控制,并存在加性—显性多基因效应,PH和MIL的最适遗传模型为E-0模型(MX2-ADI-ADI),VBH的最适遗传模型为E-3模型(MX2-A-AD);有效分枝节间距(IL)和有效分枝数(BN)的遗传均只受加性—显性—上位多基因控制,无主基因效应,其最适遗传模型为C-0模型(PG-ADI)。在B1、B2和F2世代中,PH的主基因+多基因遗传率最高,分别为71.22%、78.71%、81.87%;其次是VBH和MIL,分离世代主基因+多基因平均遗传率分别为57.10%和44.09%;IL和BN的遗传率偏低,3个世代主基因+多基因平均遗传率分别为15.24%和9.68%。相关性分析表明:PH与VBH、MIL和IL的相关性表现为极显著的正相关,相关系数分别为0.533、0.721和0.520。因此,在甘蓝型油菜理想株高育种进程中,在早代对株高进行选择是有效的,该研究也为后期开展株高相关性状QTL分析奠定基础,有利于加快油菜株高分子标记辅助育种进程。     

胶红酵母与酿酒酵母混合酒精发酵中酵母生长与糖苷酶活动力学

为了探索混合发酵中酵母生长动力学及糖苷酶活变化,评价优选的胶红酵母在葡萄酒增香酿造中的应用潜力,优化接种方案。以胶红酵母与酿酒酵母顺序接种发酵‘爱格丽’干白葡萄酒为处理,在发酵过程中,血球计数法测总酵母数量;p-NPG法测β-葡萄糖苷酶、鼠李糖苷酶、半乳糖苷酶及木糖苷酶活性;稀释平板法测2种酵母的生长变化,每24h取样,单一酿酒酵母发酵为对照。酵母生长动力学显示,顺序接种方案有助于减慢发酵速率,酿酒酵母接种时间越晚,胶红酵母的生长量随之升高且生存时间增长。4种糖苷酶主要在发酵早期表现较高的活性,混合接种发酵显著提升鼠李糖苷酶、半乳糖苷酶和木糖苷酶活性的累积量。可见顺序接种有助于降低发酵速率,增长胶红酵母生长时间,提升糖苷酶的活性,且顺序接种48h方案最具增香酿造的潜力。     

人民币汇率变动对中国农产品价格的动态传递效应分析——基于TVP-VAR模型

为探索人民币汇率变动对中国农产品价格的动态影响,基于1999年1月-2017年2月的相关数据,采用时变参数向量自回归(TVP-VAR)模型分析了人民币汇率变动对中国农产品进口价格、生产价格和消费价格的动态传递效应。结果表明:人民币汇率变动对农产品价格的传递效应具有明显的时变特征;人民币汇率对农产品进口价格、农产品生产价格和农产品消费价格传递效应存在显著差异,其中,对农产品进口价格的传递效应最大,其次是对农产品生产价格的传递效应,对农产品消费价格的传递效应最小;从长期来看,1999年以来人民币汇率对农产品进口价格和农产品生产价格的传递效应总体呈波动增加态势,而对农产品消费价格的传递效应呈先增后降的态势;不同汇率制度改革时期人民币汇率变动对农产品价格的传递效应存在明显差异。     

农业产业集聚对碳效率的影响研究:机理、空间效应与分群差异

为探究农业产业集聚对碳效率的作用机理,本研究基于随机前沿超越对数生产函数将农业碳排放纳入到农业经济核算体系之中,利用1997—2014年的面板数据对中国省域农业碳效率进行考察,并借助空间计量经济方法对农业碳效率的空间相关性及其与农业产业集聚的关系进行分析。结果表明,样本考察期内中国农业碳效率稳步增长,但受"梯度"发展模式的影响,农业碳效率具有以东部为高值"极核"区和以西部为低值"外围"区的分布结构特征。同时,区域内省份间农业碳效率的依赖性明显。而对农业产业集聚与农业碳效率关系初探后,发现二者之间整体上存在环境库兹涅茨曲线关系特征,即随着农业产业集聚度的提高,农业碳效率呈现出先得到改善后不断恶化的变化趋势。同时,处于不同集聚度下的群组情况各异,其中农业高集聚度区(中西部农业主产区)的农业碳效率随农业产业集聚度提高表现出"先升后降"的曲线特征,而在农业低集聚度区(东部经济发达区),农业产业集聚提高对农业碳效率的改善作用明显。     

甜玉米葡萄糖、果糖和蔗糖含量近红外反射光谱模型构建

甜玉米是世界上重要的果蔬两用型作物之一。建立快速、无损检测甜玉米糖分含量的方法,对于甜玉米品质育种工作中的材料鉴定、筛选具有重要意义。选取了104份糖分含量变幅较大的甜玉米材料进行了近红外光谱分析,结合酶法测量的化学值,利用偏最小二乘法以及不同光谱处理和数学处理相结合,对全光谱波段进行了化学计量学的分析统计,构建了葡萄糖、果糖和蔗糖含量的近红外光谱定标模型。用外部验证样品集进行验证,对所建模型的实际预测能力进行检验。结果表明：最优光谱处理方式葡萄糖为加权多元散射校正,果糖和蔗糖的为标准正常化加去散射处理;最优的导数处理葡萄糖为2阶导数,果糖和蔗糖的为1阶和3阶导数。葡萄糖、果糖和蔗糖定标模型的交叉验证相关系数分别为0.646、0.645、0.820,交叉验证标准偏差分别为0.321、0.275、1.508;外部验证集葡萄糖、果糖和蔗糖的预测相关系数分别为0.593、0.780、0.891,表明所建立的果糖和蔗糖预测模型具有较好的预测性,可应用于甜玉米种质资源筛选,而葡萄糖模型的预测性较差,需继续完善。