苹果套袋生产现状和存在的问题及建议

综述了国内外苹果套袋生产现状、目前苹果套袋栽培应注意的几个问题及解决方法,提出进一步完善苹果套袋栽培技术体系等建议.     

基于都市农业背景下的农业科技在农业生产中的作用

农业基础竞争力不强、比较优势逐步丧失等问题逐步成为我国今后一个时期农业面临的最大挑战,科技创新作为农业发展的重要支撑,必须发挥其引领作用,为农业转型升级增加新动能。北京国际都市农业科技园作为现代农业科技示范园区,紧紧围绕农业科技创新驱动,统筹国内外农业科技创新资源,在农业生产过程中实现科技全覆盖。该研究以北京国际都市农业科技园为例,从种子到餐桌的角度分析了农业科技在农业生产中的应用,以期为农业转型升级提供借鉴。     

鄱阳湖湿地灰化苔草群落物种多度分布格局沿水分梯度的变化

为揭示鄱阳湖湿地苔草群落的构建机制,选择灰化苔草(Carex cinerascens)群落作为研究对象,通过设立3条样带调查不同水分梯度的群落物种多度,选用断棍模型(BSM)、生态位优先占领模型(NPM)、优势优先模型(DPM)、随机分配模型(RAM)和生态位重叠模型(ONM)5个生态位模型对群落种-多度关系进行拟合,结果表明,1)灰化苔草群落可按土壤水分划分为高湿度、中湿度和低湿度3组,分别对应从湖边、湿地中间和湿地边缘的梯度分布;2)从高到低的水分梯度上,灰化苔草群落的物种数先增加后降低,优势种多度逐渐增加,物种多度分布曲线由相对平缓变为陡峭;3)高湿度灰化苔草群落物种多度分布格局的最佳拟合模型为BSM,中、低湿度的理想模型转变为NPM。研究认为,水分条件的变化是灰化苔草群落物种多度分布格局改变的主因,随着水分梯度降低,群落构建的生态学过程由随机生态位变为生态位优先占领。研究为鄱阳湖湿地多样性保育和生态功能管理提供了理论参考。     

新疆玛纳斯河流域玉米田蒸散量的估算研究

根据新疆乌兰乌苏农试站１９８７－１９８８年的试验资料,选用Ｐｒｉｅｓｔｌｅｙ和Ｔａｙｌｏｒ的农田蒸散力,作物生物学特性函数和农田土壤水分有效性函数,应用数理统计方法建立了新疆玛纳斯河流域玉米田蒸散量估算模型。该模型只需常规气象资料和农业气象资料,计算简便,具有较高的精度,便于在干旱区推广使用。     

尿素在草甸褐土中分解转化特征及影响因素的研究

采用好气培养法对２０℃和３５℃两种培养温度下,尿素和尿素混施ＤＣＤ在草甸褐土中的氮转化进行了研究,结果表明：草甸褐土的尿酶活性与硝化活力均较强,尿素施入土壤后即迅速水解,２ｄ时已水解１９．９９％～８５．０２％,ｄ水解９０％以上。转化生成的ＮＨ＾＋４－Ｎ,很快进行硝化作用,生成ＮＯ＾－３－Ｎ并在土壤中积累。土壤氮的矿化随培养温度的升高和培养时间的延长明显增加,表明在温度较高、作物吸收能力弱的多雨季节     

固体氧化钴pH电极的研制

本文制备了一种可用于溶液pH值测定的固体氧化钴印刷电极。该电极可在2～12pH范围内呈现出良好的Nernst响应。文中就氧化钴的合成方法及印刷电极的制备工艺参数对电极响应行为的影响进行讨论。     

双凤水库浮游生物的研究

本文报道了1993年5、7、9月,1997年9月双凤水库浮游生物调查研究结果。浮游植物生物量平均10．472mg/L,兰藻54．9％;浮游动物量平均6．945mg/L,轮虫占52．7％,同时讨论了浮游生物与银鲫生长的关系。     

双波灯诱集棉铃虫的效果评价

通过对１９９６ ～１９９８ 年３ ａ 的双波灯与杨树把诱集棉铃虫的结果比较分析,双波 灯诱蛾具有诱蛾数量多、蛾峰明显、雄蛾多于雌蛾等特点。可以将之用于棉铃虫的预测预报。     

红富士苹果套袋后果皮中花青苷积累与酚类物质代谢的关系

以红富士苹果为试材,分别在山东栖霞和泰安研究了套袋后果皮中酚类物质代谢与花青苷积累的关系。结果表明,套袋后果皮花青苷积累与酚类物质代谢密切相关。果皮中多酚氧化酶（PPO）含量较对照（不套袋果）降低,过氧化物酶（POD）和苯丙氨酸解氨酶（PAL）较对照升高,类黄酮、水溶性酚和花青苷含量较对照增加,果实着色迅速而良好。但在摘袋后气候不利和果袋为劣质单层纸袋条件下,果皮中酚类物质和花青苷含量均低于对照。     

Reproductive performance and offspring quality of Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards) females fed an optimized formulated diet and the razor clam Sinonovacula constricta

After feeding female Eriocheir sinensis on an optimized formulated diet or fresh razor clam Sinonovacula constricta for 7 months, their reproductive performance and offspring quality were compared. To evaluate diet nutrient contents, the proximate, fatty acid and amino acid compositions of the formulated diet and the razor clam were analysed. The nutritional value of the diets was determined by assessing survival, gonadosomatic index (GSI) and hepatosomatic index (HSI) of female crabs from both diet treatments, together with the percentage of females that spawned, total egg production per female and fecundity (number of eggs g^?1 female wet weight). Furthermore, the quality of eggs and newly hatched larvae from the two dietary treatments were determined using the following parameters: egg diameter, wet weight and dry weight, hatchability, proximate and fatty acid profile of eggs, larval carapace length, resistant to starvation and osmotic shock, larval survival and development to the zoea II stage. Higher protein, phospholipids (PL) and amino acids (AA) contents were found in the razor clam while the formulated diet contains higher levels of ash, total lipid (TL) and 18:1n‐9, 18:2n‐6 and 22:6n‐3 fatty acids. Although female crabs fed the two different diets showed similar reproductive performances, newly hatched zoea I larvae produced by the crabs fed the formulated diet had significantly longer mean carapace length and shorter development time to the zoea II stage under identical culture condition (P<0.05). Moreover, dietary fatty acid appeared to have more significant effects on the fatty acid composition of the hepatopancreas than it did on mature ovaries or eggs. This suggests that the fatty acid profile of mature ovaries is indicative of the specific fatty acid required for ovarian development in E. sinensis. In conclusion, our results show that the optimized formulated diet developed in this laboratory can totally replace the razor clam, a broodstock food widely used in E. sinensis hatcheries in China. This encouraging result should facilitate more reliable hatchery production of this important aquaculture species.