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61.
为保护蔬菜的优质优价及质量安全,以上海9个农业产区(宝山区、崇明区、奉贤区、嘉定区、金山区、闵行区、浦东新区、青浦区和松江区)蔬菜为研究对象,分析不同产区蔬菜的δ15N值差异及其对种植模式(常规、绿色或有机种植)的指示;对δ13C、δ15N、δ2H和δ18O值进行单因素方差分析,并应用主成分分析(PCA)、偏最小二乘判别分析(PLS-DA)及支持向量机(SVM)方法,建立上海地产蔬菜产地判别模型。结果表明,宝山区、松江区和嘉定区蔬菜的δ15N值占前三,且分别与δ15N值最低的浦东新区蔬菜(4.44‰)存在显著差异,且仅有浦东新区蔬菜可能为绿色或有机种植的比例低于50%;δ13C、δ2H和δ18O值只在部分产区间差异显著,PCA可初步实现浦东新区蔬菜与其他8个产区的鉴别;PLS-DA最优模型可以很好地实现浦东新区蔬菜产地判别(预测准确率为98.80%),SVM最优模型可以很好地实现宝山区(预测正确率96.38%)、嘉定区(预测正确率92.77%)和青浦区(预测正确率91.57%)蔬菜的产地判别,SVM最优模型可以较好地实现金山区、松江区、崇明区和奉贤区蔬菜的产地判别。本研究结果为上海地产蔬菜种植模式及产地判别提供了参考方法,并为其溯源和质量安全保护提供了基础数据。 相似文献
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Consistent spray coverage that is evenly distributed throughout the canopy is necessary to control pest populations that can negatively affect yield. As applicators are switching to Coarser spray quality nozzles to reduce risk and liability of pesticide spray drift, concerns about efficacy loss are growing. Previous research has indicated that small droplets are the most effective at penetrating through crop canopies, but newer nozzle technologies have improved the effectiveness of larger droplet or Coarser sprays. Research was conducted to assess the canopy penetration of nozzles that produce Coarse, Very-Coarse and Extremely-Coarse spray qualities compared to nozzles that produce Fine and Medium spray qualities. Kromekote collectors were positioned in four configurations in an oat (Avena sativa L.) var. ‘Yarran’ (AusWest Seeds, Forbes, NSW, Australia) crop to quantify the coverage and droplet number densities (droplets cm−2) across three application carrier volume rates: 50, 75 and 100 L ha−1. Applications were made in the field in 30 cm tall, tillering oats, with collectors arranged in a randomised complete block design with three replications. The entire study was repeated on the following day. Results showed that droplet number densities were inversely related to the droplet size produced by the nozzles, yet coverage was increased more by application volume rate than droplet size. Thus, both spray drift reduction and improved canopy penetration can be achieved with proper nozzle selection and operation parameters for the control of agronomic pests. 相似文献
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Grain legumes play an important role in community livelihood and in the national economy in Kenya. Unfortunately, in many African countries, production doesn't satisfy the demand in grains due to various constrains. Understanding farmers practices and behavior in the management of grain legume pests is a crucial step in the development of sustainable management strategies. A total of 216 farmers were surveyed in eight districts of eastern Kenya to evaluate farmers' knowledge and perceptions of grain legume pests; to examine current pest management practices, and to identify other production constraints. Grain legumes are grown by a wide age-group of farmers, with both genders equally represented. Chemical control remains the main pest management strategy, and, to ensure pesticide effectiveness, farmers also use increased application rates, chemical alternation, frequent application and mixtures of chemicals. While farmers used other control measures, they showed only limited interest in biological control. The majority of the farmers had experience in grain legume farming and were able to identify the major pests, which were the legume flower thrips Megalurothrips sjostedti Trybom, the cowpea aphid Aphis craccivora Koch and the legume pod borer Maruca vitrata Fabricius. Our survey revealed that education and proximity to extension services contributed significantly to farmers' knowledge of grain legume pests, suggesting the need to provide continuous training and capacity building on integrated pest management in grain legume farming. The study also suggests integration of other pest management strategies such as the use of early maturing varieties, biopesticides and biofertilizer to reduce the use of chemical for sustainable pest management. 相似文献
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松针粉富含多种营养成分,并且具有一定的药用价值。文章对我国松针的资源概况、松针粉的营养价值、药效及在生产上的应用情况进行概述,并对松针粉未来的研究方向进行展望。 相似文献
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3种水质调控方式下刺参池塘初级生产力的周年变化 总被引:1,自引:0,他引:1
通过对自然纳潮、微孔曝气、养水机池塘不同水层初级生产力及其相关参数的研究,分析养水机对初级生产力的影响。结果表明,3种水质调控方式池塘,初级生产力年均值、P/R值均以养水机池塘最高,微孔曝气池塘次之,自然纳潮池塘最低。养水机池塘、微孔曝气池塘、自然纳潮池塘的初级生产力年均值分别为(6.22±0.54)、(5.37±0.60)、(4.69±0.53) gO_2/(m~2·d)。3种水质调控方式下,养水机池塘30~50 cm水层和50~100cm水层初级生产力差异不显著,而微孔曝气池塘和自然纳潮池塘这两水层之间初级生产力差异显著,且养水机池塘50~100 cm的水层初级生产力显著高于微孔曝气和自然纳潮池塘。研究表明,养水机能显著提高刺参池塘50 cm以下水层的初级生产力,缩小上层和下层初级生产力之间的差距,从而提高池塘水体总初级生产力,为刺参饵料和池塘物质快速循环提供基本保障。 相似文献
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为研究不同贮藏方式对鲜食核桃在贮藏过程中品质的影响,以“清香”核桃鲜果为试材,分别采用青果贮藏((0±1) ℃、相对湿度70%~80%)、去青皮的湿果贮藏((-7±1) ℃、相对湿度70%~80%)及湿果真空贮藏((-7±1) ℃、相对湿度70%~80%)3种方式贮藏,每15 d对其品质指标进行观察测定。结果表明:随着贮藏时间的延长,所有贮藏方式处理的鲜食核桃的感官品质和营养成分均呈一定的下降趋势。其中,青果贮藏能较好地保持核仁的含水量,维持粗脂肪、蛋白质及可溶性糖含量的稳定性,贮藏后种皮色泽较好,核仁容易剥皮、风味较好,但果壳容易产生霉变;湿果贮藏和湿果真空贮藏可以减轻鲜核桃的霉变,延长了鲜核桃贮藏期,但随着贮藏时间的延长,湿果贮藏核仁水分散失较快,粗脂肪、蛋白质及可溶性糖含量变化较大,使得种皮色泽降低,核仁剥皮困难、风味下降。 相似文献