Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates   总被引：4，自引：0，他引：4  

Mahdi Gheysari  Seyed Majid Mirlatifi  Mehdi Homaee  Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954

Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha⁻¹), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43 kg N ha⁻¹, for the 142 kg N ha⁻¹ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60 cm depth was 46 and 138 mg l⁻¹, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.  相似文献   

Effects of formalin on total haemocytes count and histopathological changes in the shrimp Litopenaeus schmitti (Pérez‐Farfante & Kensley 1997)     

Raico E Laria Lamela  Yanis Cruz Quintana  Raquel Silveira Coffigny  Mercedes Martínez  Norma González Herrate 《Aquaculture Research》2008,39(12):1316-1321

Formalin is used in shrimp industry to eliminate ectoparasites and as a disinfectant. However, the effect of formalin on shrimp's defense mechanism is unknown. Several biomarkers were used to assess the immune response of juveniles of the shrimp Litopenaeus schmitti exposed to different concentrations of formalin (10, 25 and 50 mg L^?1) during 24 and 48 h. Formalin concentrations of 25 and 50 mg L^?1 produced a significant reduction in the total haemocyte count at both 24 and 48 h. Peroxidase and phenoloxidase activity did not show variations. The total protein concentration in haemolymph of shrimps was not significantly different between experimental groups. Histological analysis showed hyperplasia in the gills of animals exposed at 10 mg L^?1 for 24 h; however, the exposure at 25 and 50 mg L^?1 caused necrosis in gills, hepathopancreas and the antennal gland.  相似文献   

Antioxidant properties of blackberry and blueberry fruits grown in the Black Sea Region of Turkey     

Ilkay Koca  Bulent Karadeniz 《Scientia Horticulturae》2009

Seven wild and ten cultivated blackberries (Arapaho, Bartin, Black Satin, Bursa 1, Bursa 2, Cherokee, Chester, Jumbo, Navaho, and Ness), and six lowbush (Vaccinium arctostaphylos) and four highbush (Vaccinium corymbosum) blueberries fruits (Ivanhoe, Jersey, Northland, and Rekord) were analyzed for total anthocyanins, total phenolics, and antioxidant activity as ferric reducing antioxidant power (FRAP) in this study. The respective ranges of total anthocyanin and total phenolic contents of the tested samples were: blackberries, 0.95–1.97 and 1.73–3.79 mg g⁻¹ and blueberries, 0.18–2.94 and 0.77–5.42 mg g⁻¹. FRAP values varied from 35.05 to 70.41 μmol g⁻¹ for blackberries, 7.41 to 57.92 μmol g⁻¹ for blueberries. Wild blackberries had the highest FRAP values while wild blueberries had the highest total phenolic and total anthocyanin contents. A linear relationship was observed between FRAP values and total phenolics for blueberries (r = 0.981). The anthocyanin pigments in samples were isolated and characterized by high-performance liquid chromatography (HPLC) with UV–visible detection. Cyn-3-glu was the predominant anthocyanin in all blackberry fruits.  相似文献   

中国蔬菜绿色全要素生产率时空特征与空间错位          下载免费PDF全文

赵梦璇  张军以 《农业工程学报》2024,40(2):344-355

为评估中国蔬菜绿色生产率，提升蔬菜生产绿色发展水平，推进农业高质量发展。该研究采用超效率SBM-ML模型、空间错位指数、主成分分析法等方法，探究2011—2020年中国30个省市蔬菜绿色全要素生产率的时空格局演变与空间错位特征，识别影响中国蔬菜绿色全要素生产率的主要因素。研究结果发现：1）2011—2020年中国蔬菜绿色全要素生产率整体呈下降趋势，由1.023 1降低到0.741 4，蔬菜生产与生态环境可持续发展的协调程度降低，其中技术效率下降和技术退步共同拖累了蔬菜绿色全要素生产率的提高。2）2011—2020年中国蔬菜绿色全要素生产率增长呈“东高西低，南高北低”的空间分布特征。北回归线以南产区蔬菜绿色全要素生产率最高，西北产区蔬菜绿色全要素生产率最低，其差异主要取决于水土资源供给状况与市场需求规模等因素。3）2011—2020年中国蔬菜绿色全要素生产率与技术效率的空间错位由北向南大致呈现“正向错位—负向错位”的变化趋势，整体以低错位为主。东北产区、中部产区地势平坦，农业生产条件良好，有利于蔬菜规模化种植。2011—2020年中国蔬菜绿色全要素生产率与技术进步的空间错位呈显著的“东正西负”的空间分布特征，且空间错位程度较大，负向错位省份数量由13个增至17个。由于蔬菜生产过于追求经济效益，忽视了绿色生产技术的投入。4）经济发展水平、资源环境禀赋和交通通达性是影响中国省域蔬菜绿色全要素生产率变化的主要因素，其中城镇化率和人均可支配收入等经济要素对蔬菜绿色全要素生产率的影响最为明显。研究结果可准确把握现阶段蔬菜绿色生产现状，为农业绿色转型发展提供借鉴。  相似文献   

氮添加对内蒙古不同草原生物量及土壤碳氮变化特征的影响     

韩小雨  郭宁  李冬冬  谢明阳  焦峰 《草业学报》2022,31(1):13-25

以内蒙古草甸草原、典型草原、荒漠草原3种草原实验区草地植物群落为研究对象, 设置7种氮添加梯度, 分别为CK（0 g N·m^-2·a^-1）、N₁（5 g N·m^-2·a^-1）、N₂（10 g N·m^-2·a^-1）、N₃（15 g N·m^-2·a^-1）、N₄（20 g N·m^-2·a^-1）、N₅（25 g N·m^-2·a^-1）、N₆（30 g N·m^-2·a^-1）,应用单因素方差分析（One-way ANOVA）方法研究不同浓度梯度氮添加下不同草原类型区植被生物量、土壤碳氮差异及其影响因素。结果表明：1）氮添加并未对3种草原类型地下生物量产生显著影响（P>0.05）,但显著提高了草甸草原和荒漠草原地上生物量（P<0.05）,且本研究初步判断在N₃添加时接近饱和阈值, 整体上氮添加使内蒙古草原总生物量平均增加了29.66%,较干旱的荒漠草原对氮添加的响应较为明显。施氮肥使草甸草原的根冠比显著降低（P<0.05）,典型草原根冠比在N₃处理下显著增加（P<0.05）,但对荒漠草原影响不显著（P>0.05）。2）选择不同土层（0~10 cm、10~30 cm）分析氮添加对3种草地类型土壤有机碳、全氮含量的影响, 结果显示氮添加对草甸草原土壤碳氮含量没有显著影响（P>0.05）,对典型草原和荒漠草原土壤碳氮含量存在显著影响（P<0.05）,且0~10 cm土层对施氮的响应更明显。3）施氮条件下地上生物量与土壤C/N、年均降水显著相关（P<0.01）,地下生物量、总生物量均与土壤全氮含量、有机碳含量、土壤C/N、年均温、年均降水显著相关（P<0.01）。总的来说,不同类型的草地生态系统生物量及土壤碳氮含量对施肥的响应存在差异,这意味着草地恢复与管理过程中需要对养分的添加作用进行考虑。  相似文献   

拉缘蝽为害对卵叶小蜡内含物含量的影响     

张潮巨 《福建林业科技》2006,33(3):60-64

通过对受拉缘蝽不同程度为害的卵叶小蜡叶片的单宁、黄酮、总酚含量的测定,结果表明:受害的卵叶小蜡叶片的单宁含量随着拉缘蝽若、成虫为害程度的加重而发生变化,在受害初期显著增加,但随着为害程度的加重,而呈逐渐下降的趋势;受害卵叶小蜡叶片中黄酮含量随着受害程度的加剧,呈先上升、而后再下降的特点;叶部总酚的含量随着受害程度的不断加重,总酚的含量呈现上升的趋势。说明卵叶小蜡应激反应的过程是一种随着受害程度的不同而不断变化的动态过程。  相似文献   

匀浆法提取沙棘果中总黄酮的工艺研究   总被引：6，自引：0，他引：6  

赵春建  祖元刚  付玉杰  李春英  王延兵  侯春莲 《林产化学与工业》2006,26(2):38-40

为了建立一种高效提取沙棘果中总黄酮的方法,对匀浆法提取沙棘果中总黄酮的工艺进行了研究,确定了最佳的工艺参数:提取原料为含水率85%的沙棘果,溶剂为85%的乙醇,匀浆时间10 m in,液固比为5∶1(mL∶g)。将该法与常规的回流提取法进行了比较。结果表明,在优化的条件下,匀浆法对沙棘果总黄酮的提取率为0.76%,与回流提取相当。匀浆提取法所用提取时间短,提取溶剂用量少,该法是一种高效、快速提取沙棘果总黄酮的方法。  相似文献   

Validation of a small-area method for estimating the spatial distribution of the degree of tree damage     

Rafał Podlaski 《European Journal of Forest Research》2004,123(3):229-237

This article presents a validation of a method, proposed in Podlaski (2003), for estimating the degree of tree damage. This method belongs to a group of small-area methods. To estimate the degree of tree damage in individual P₃ sub-blocks of the SINUS system of information on the natural environment, a classification based on the degree of defoliation was used. Spatial distribution of the degree of tree damage was estimated through unrestricted simple random sampling. The maximum total estimation error for proportions of fir and beech with a damage degree of zero, and also with second and third degrees jointly, reached a maximum of 35.6% for fir, and 33.8% for beech. P₃ sub-blocks characterised by the highest proportion of the healthiest trees (at least 15% being undamaged trees) occurred in patches in the case of fir, and in larger, compact areas in the case of beech. Because spatial diversification in the health of fir, and to a smaller degree in the case of beech, occurs at small scales, small-area methods for estimating tree condition are necessary. An analogous scheme, combining small-area with large-area methods (utilising sub-blocks of the network of large-area systems in a small-area inventory, and establishing a common database), could be used on a wider scale; for example, by supplementing the program of estimating tree health carried out by the United Nations Economic Commission for Europe (Lorenz et al. 2002) with local inventories.  相似文献   

在低温锻炼中毛白杨幼苗可溶性总蛋白、RNA、DNA、RNase及抗冻性的变化   总被引：4，自引：0，他引：4  

林善枝  张志毅 《中国林学(英文版)》2002,4(2):9-15

低温锻炼不仅提高了毛白杨幼苗存活率和抗冻性以及RNA和可溶性总蛋白的含量 ,降低了RNase活性 ,而且能减轻低温胁迫引起的RNA和可溶性总蛋白含量的下降程度和RNase活性的提高 ,有利于幼苗在恢复过程中RNA和可溶性总蛋白水平的迅速回升以及RNase活性的降低 .进一步研究发现 ,DNA含量无论在低温锻炼中还是在低温胁迫下或是在随后的恢复生长期均保持相对稳定 ;低温锻炼所引起的RNA含量的增加 ,与RNase活性的降低呈明显的负相关 ,与可溶性总蛋白含量的增加以及幼苗抗冻性的提高成正相关 .这表明低温锻炼可能抑制RNase活性 ,有效地促进RNA含量的增加 ,而RNA可能参与了可溶性总蛋白的合成及抗冻性的诱导  相似文献   

苦丁茶黄酮类化合物的提取与分析   总被引：5，自引：0，他引：5  

李建法  胡六江  吕金红  唐晶晶 《浙江林业科技》2005,25(1):31-34

采用不同浓度的乙醇溶液提取苦丁茶中的黄酮类化合物,通过提取效果的对比,确定了合理的乙醇浓度为70%～80%.研究表明,与单纯采用溶剂提取相比,采用超声振荡辅助提取对黄酮类化合物的相对提取率影响较小,但是可以缩短提取时间、降低提取温度,有利于提取过程中生物活性成分的保持.与小叶苦丁茶(粗壮女贞)相比,在相同提取和分析条件下,浙江本地产的大叶苦丁茶(大叶冬青)中黄酮类化合物含量较多.  相似文献