藜麦叶片黄酮类物质的提取及基因型差异

为了优化藜麦Chenopodium quinoa叶片黄酮的乙醇提取工艺和分析基因型间的差异,为藜麦黄酮的开发和高黄酮的品种筛选提供理论依据,采用3因子3水平正交试验设计,探讨了乙醇体积分数、料液比和浸提时间等因素对藜麦叶片黄酮提取率的影响;并采用最佳提取条件,对10个不同基因型品种藜麦的叶片黄酮得率进行了比较分析。结果表明:藜麦叶片黄酮最佳提取条件为体积分数70%乙醇,1∶40料液比,80℃水浴下回流浸提0.5 h。在优化条件下,1次提取工艺得率达85%以上。各因素对叶片黄酮提取率的影响程度依次为:浸提时间>乙醇体积分数>料液比。比较结果发现:藜麦叶片黄酮得率存在明显基因型差异,其中品种PI814932的叶片黄酮类物质得率最高,达0.933%。所测藜麦品种的叶片黄酮平均得率为0.619%,变异系数为34.44%。研究表明:乙醇回流法适于提取藜麦总黄酮类化合物。     

燕麦散黑穗病菌冬孢子萌发条件研究

为明确燕麦散黑穗病菌(Ustilago avenae)冬孢子在自然生境中的萌发条件,研究了疏亲水界面、不同温度、湿度、光照时间、pH、碳源和氮源对冬孢子萌发的影响。结果表明,亲水界面促进冬孢子萌发,在水琼脂培养基上萌发率最高;冬孢子萌发的最适温度为20~25℃,温度过高或过低均抑制其萌发。冬孢子对湿度要求较高,RH≥90%时才可萌发,且萌发率较低。光照对冬孢子萌发的影响不明显,酸性条件有利于冬孢子萌发,最适pH为4~7,葡萄糖和蛋白胨可促进冬孢子萌发。     

Economic effects of proposed changes in living conditions for laying hens under the National Organic Program

In this paper, we estimate the costs and benefits of implementing the proposed National Organic Program for laying hens compared with alternatives. For the regulatory proposals under option 2, the regulatory cost will be zero because most producers are already in compliance with the proposed regulation. The anticipated benefits of this regulation will be zero as well, because the current market prices already reflect consumers’ willingness to pay for the existing animal welfare conditions. For the regulatory proposals under option 3, before market adjustments, the average regulatory burden for the entire organic egg industry will amount to $0.09 per dozen eggs, with extreme variations between $0 for small operations and $2.30 per dozen for large operations. If we rely on the average price of organic eggs, $2.69 per dozen, and assume a maximum estimated benefit associated with improved animal welfare conditions, that consumers would be willing to pay of about 30% above the current market price, the estimated benefit of regulation amounts to $0.81 per dozen eggs. Based on the findings, we conclude that option 2 is welfare neutral and could be easily adopted because it already has been adopted by representative producers. For option 3, the benefit-cost ratio is larger than 1, which indicates that the proposal passes the benefit-cost ratio test. The obtained result, however, has to be interpreted with serious reservation because of the differential effect that the proposed regulation would have on different industry participants. Under option 3, the effect of the proposed changes on small organic egg producers is negligible because most small producers are operating under conditions similar to the proposed living standards. However, costs will increase substantially for large organic egg producers and likely cause a substantial number of producers to exit organic production and switch to conventional production, which would cause a substantial decline in the prices of conventional eggs and organic feed in the short run.     

Temperature conditions in the Argentine chub mackerel (Scomber japonicus) fishing ground: implications for fishery management

We describe the seasonal migrations of Argentine chub mackerel ( Scomber japonicus ) into the fishing ground in relation to sea surface temperature conditions and analyse the temperature evolution during the fishing season on the basis of 1955–97 time-series. The upper temperature limit for the presence of schools was around 19°C. At higher values, most schools leave coastal waters (< 50 m) for the shelf. An inverse relationship was observed between catches per unit of effort (CPUE) of the inshore fishery and sea surface temperature. The highest standardized CPUE values corresponded to temperatures lower than 19°C. Above this temperature, the probability of obtaining a standardized CPUE higher than 1 was extremely low, and the standard deviations were minimal. The economic benefit from catches was also analysed through the different months of the fishing season. It was found that the mean benefit corresponding to temperatures lower than 19°C exceeded approximately 15 times that obtained at higher temperatures. A simple fishing strategy was proposed to the commercial fleet in order to improve the economic benefit of the catches. The migratory pattern followed by mackerel during the spawning period was also analysed in relationship to other environmental factors like food availability. Zooplankton composition, size structure and abundance in coastal and shelf waters are described, and their implications for feeding ecology of larvae and adults of the species are discussed.     

海南橡胶气象服务进展及效益分析

气象信息服务对提升天然橡胶产业防灾减灾能力有着重要价值。2011年海南橡胶气象台积极与海胶集团合作,陆续建设了海南省橡胶气象服务监测网、橡胶气象信息发布平台、基于web的橡胶气象信息服务系统和手机短信息发布平台,开发了多种橡胶气象服务产品,为胶农及时有效的提供割胶天气预报,最大限度地避免和减少了雨冲胶的次数,为胶农适时进行割胶补刀作业提供了科学决策依据,对橡胶生产产生了良好的经济和社会效益。     

Estimating theoretical radiation‐use efficiency for kale crops

Establishing the radiation‐use efficiency (RUE) of forage brassica crops will aid our understanding of their photosynthetic performance. The concept of RUE has been developed for cereals and legumes, but there is limited information for forage brassica crops. Three experiments defining the influence of different sowing dates on ‘Gruner’ kale (Brassica oleracea acephala L.) dry matter production were conducted at Hastings (Hawkes Bay) and Lincoln (Canterbury) in New Zealand between 2002 and 2009. These trials were also evaluated for radiation interception and RUE. Delayed sowing increased RUE in two out of three experiments across sites: from 1·93 g MJ^?1 photosynthetically active radiation (PAR) for December‐sown crops to 2·72 g MJ^?1 PAR (P < 0·001) for January‐sown crops at Hastings and from 1·50 for September‐sown crops to 2·00 g MJ^?1 PAR (P < 0·001) for November‐sown crops at Lincoln. The different sowing dates and years of experimentation provided a range of mean temperatures (from 13 to 16°C) during the vegetative period. Across years and sowing dates, RUE was strongly correlated with mean temperature (R² = 0·81) and sowing date (R² = 0·64), but weakly correlated with season length (R² = 0·11) and dry matter (R² = 0·002). There was also a strong correlation (R² = 0·83) between sowing date and mean temperature. The increase in RUE with delayed sowing was therefore mainly attributed to increased mean temperatures. Radiation‐use efficiency increased at about 0·41 g MJ^?1 for each 1°C increase from 13 to 16°C.     

低温下硅对春小麦种子萌发及抗氧化和渗透调节系统的影响

为了解硅缓解低温胁迫春小麦种子萌发的作用,以春小麦品种龙麦26和克旱16为材料,分析了低温条件下硅酸钠处理后春小麦种子萌发、渗透调节物质含量和保护酶活性的变化。结果表明,低温条件下硅酸钠处理后,春小麦种子萌发显著受到促进,发芽率、发芽势、发芽指数和活力指数提高,其中以1.0mmol·L-1硅酸钠处理效果最好;小麦种子α-淀粉酶、超氧化物歧化酶、过氧化物酶活性以及可溶性糖含量显著提高,丙二醛含量、外渗电导率和脯氨酸含量显著降低。说明外源硅可缓解低温对春小麦种子萌发产生的影响。     

白砂糖干燥与冷却机理及影响

砂糖的含水量、装包温度和仓储条件对其贮存保质具有重要影响。本文从白砂糖的含水分特性、干燥机理和生产过程环节等对白砂糖干燥与冷却的影响进行深入分析。由于结晶过程的包裹现象,砂糖含水分可分为表面和内部水分,白砂糖干燥过程只能去除前者。生产过程中煮糖、分蜜操作对内部水分含量有影响。贮存过程的内部水分的扩散是砂糖降质的根本原因,而装包温度和贮存条件是影响内部水分扩散的外在条件。     

2022年夏收粮油作物生育期气象条件及其影响分析

基于主产区气象观测站和农业气象站实测气象资料和作物发育期资料,计算冬小麦和油菜生长季的气候适宜度和灾害指数等参数,评价该阶段气象条件对夏收粮油作物的利弊影响。结果显示：2021/2022年度冬小麦、油菜生育期内,产区大部光热充足、土壤墒情适宜,冻害、干旱等农业气象灾害影响程度偏轻,气候适宜度高于上年和近5a平均值,气象条件利于夏收粮油作物生长发育和产量形成;成熟收获期间多晴好天气,收获进度快、质量高。但北方冬麦区秋播期多雨渍涝,冬小麦播种期明显推迟,冬前壮苗比例偏少、分蘖不足。江南和贵州等油菜产区冬季持续阴雨寡照,影响油菜发育进程。     

2021年秋季气象条件对农业生产的影响评价

2021年秋季（9−11月）,全国平均气温为10.5℃,较常年同期偏高;全国平均降水量为157.9mm,为1961年来最高值,尤其西北地区、华北、黄淮区域平均降水量均为1961年以来历史同期最高值;全国平均日照时数为564.9h,为1961年以来第9低值。东北地区大部初霜期较常年明显偏晚,全国秋收区光温条件总体利于作物灌浆成熟和收晒。西北地区东部、华北大部和黄淮北部秋季前期多雨和寡照突出,属典型“埋汰秋”,麦播期普遍推迟7～15d,秋季中后期天气转好,冬小麦播种速度加快。秋末华北、黄淮、西北地区东部冬小麦发育期较常年普遍偏晚7～25d,处于分蘖期的占比低于常年和2020年同期,全国冬小麦晚弱苗比例高于常年和2020年同期。南方大部地区秋播期间农田土壤墒情适宜,冬小麦、油菜播种和出苗顺利,发育期基本接近常年。