不同生长年限王草的营养价值研究

本文对生长第1、2、3年的王草在100cm高度时刈割的营养成分及其体外干物质、有机物降解率进行分析研究。结果表明:不同生长年限王草第1年的粗蛋白质显著高于第2、3年(P<0.05),而中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)显著低于第3年(P<0.05)。干物质、有机物的降解率第1年最高,第3年的最低,但差异不大。     

海南岛各县与世界热带国家农业气候相似性研究

本文以海南岛气候资源、热作生产实际及农业气候相似性原理为依据,选取年均温及月均温的年内分配,年雨量及月雨量的年内分配共26个具有农业意义的气候因子,采用多元统计中的相似分析方法,通过上机运算,取得了海南岛各县与世界热带21个国家24个点站的农业气候相似系数,并按系数的大小进行了相似性等级区划;最后与实际数据进行印证对比,结果表明,各地的理论系数及其相似性等级划分与实际吻合,具有较好的指导意义。     

盐土和非盐土施氮对多花黑麦草增产改质效果差异的比较

本研究对盐土和非盐土种植多花黑麦草进行氮肥施用试验,研究施氮对不同土壤条件下多花黑麦草产量及饲用品质的影响,为提高氮肥利用效率、有效改善牧草产量品质提供依据。试验分别在江苏大丰金海农场和南京六合江苏省农业科学院试验基地进行,设置N₀(对照)、N₁(氮用量100 kg/hm²)、N₂(氮用量150 kg/hm²)和N₃(氮用量200 kg/hm²)4个处理,分别在多花黑麦草拔节期和初穗期进行刈割,测定牧草产量和饲用品质。结果表明在盐土和非盐土施用氮肥对多花黑麦草饲草品质和产量的影响存在显著差异:非盐土条件下不同施氮处理的多花黑麦草产量和饲用品质均高于盐土,其中干物质体外消化率(IVDMD),粗蛋白(CP)和非结构性碳水化合物(NSC)含量非盐土条件下高于盐土,且第1茬高于第2茬;CP含量随着施氮量的上升而升高,而NSC含量随着施氮量的上升而下降;作为NSC主要组分的淀粉在盐土条件下的含量高于非盐土;施氮组的IVDMD高于对照,但不同施氮量间差异不显著;中性洗涤纤维(NDF)含量盐土条件下高于非盐土,第2茬高于第1茬;盐土不同茬次、不同施氮处理的干物质含量(DM)均显著高于非盐土,且第2茬高于第1茬,并随着施氮量的增加而下降;非盐土条件下的牧草产量高于盐土,且第2茬高于第1茬,随着施氮量的上升而升高,N₂处理组,即氮素施用量150 kg/hm²的产量最高;但在盐土上施氮,多花黑麦草的产量增加幅度高于非盐土。     

草坪草耐热性研究进展

本文对近年来草坪草耐热性方面的研究进行了综述,包括栽培管理和营养调节等基本耐热影响因素;植物生长调节剂对提高冷季型草坪草抗热性的研究;草坪草耐热性生理机理及抗或耐热性筛选指标的研究;抗热性基因的定位、分离克隆以及转基因提高耐热性研究;以及热击蛋白及其编码基因方面的研究。最后作者还提出了利用耐热性DNA聚合酶提高草坪草耐热性的一点看法。     

Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats.

The purpose of this study was to describe the clinical, radiographic, and computed tomographic findings in dogs and cats with migrating intrathoracic grass awns. Thirty-five dogs and five cats with visual confirmation of a grass awn following surgery, endoscopy or necropsy, and histology were assessed. The medical records and all diagnostic imaging studies were reviewed retrospectively. Labrador Retrievers or English Pointers < 5 years of age, with a history of coughing and hyperthermia, were the most common presentations. Seventeen animals had an inflammatory leukogram of which 14 had a left shift or toxic neutrophils. Radiographs were performed in 38 animals and computed tomography (CT) in 14. Thoracic radiographs were characterized by focal pulmonary interstitial to alveolar opacities (n = 26) that occurred most commonly in the caudal (n = 19) or accessory lobes (n = 8). Additional findings included pneumothorax (n = 9), pleural effusion (n = 8), and pleural thickening (n = 7). Pulmonary opacities identified on radiographs correlated to areas of pneumonia and foreign body location. CT findings included focal interstitial to alveolar pulmonary opacities (n = 12) most commonly in the right caudal lung lobe (n = 9), pleural thickening (n = 11), mildly enlarged intrathoracic lymph nodes (n = 10), soft tissue tracking (n = 7) with enhancing margins (n = 4), pneumothorax (n = 6), pleural effusion (n = 4), and foreign body visualization (n = 4). Histologic diagnoses included pulmonary and mediastinal granulomas or abscesses, bronchopneumonia, and pleuritis. Migrating intrathoracic grass awns should be considered as a differential diagnosis in coughing, febrile animals with focal interstitial to alveolar pulmonary opacities, pleural effusion, pleural thickening, and/or pneumothorax on radiographs or CT.     

Changes in soil macropores: Superposition of the roles of organic nutrient amendments and the greenhouse pattern in vegetable plantations

Organic farming can potentially mitigate soil compaction, which commonly occurs in vegetable plantations, particularly in greenhouses when compared with open‐air systems. Although several studies have addressed the effect of planting patterns on soil pore characteristics, few studies have focused on changes in pore attributes under organic fertilization. We used adjacent fields during green manure planting as a control to compare the differences in soil physicochemical and macropore parameters between 14‐year‐old greenhouse plots and open‐air plots under organic fertilization. Pearson's correlation analysis was performed to analyse the drivers of soil macropore characteristics in vegetable plantations in Jiangsu Province, China. A significant increase in connectivity, fractal dimensions and total macroporosity and a decrease in bulk density after 14 years of organic farming, particularly in the surface layer in the greenhouse, were observed. However, the difference in pores in the plough pan layer was not significant between the treatments. The volume of small pores (50–500 μm) and medium pores (500–1,000 μm) increased significantly (p < 0.05) in both the greenhouse and open‐air systems, showing significantly positive relationships with soil organic matter (SOM) and total nitrogen (TN) content. Large pores (>1,000 μm) showed a clear decrease, especially in open‐air fields, possibly due to the disappearance of the original straw residues in the surface layer. Small and medium pores in the plough layer increased in greenhouse fields, whereas the opposite occurred in open‐air fields. Overall, compared with open‐air systems, long‐term organic greenhouse patterns had a significantly positive effect on soil pore attributes.     

Horse Preference,Forage Yield,and Species Persistence of 12 Perennial Cool-Season Grass Mixtures Under Horse Grazing

Cool-season grass mixtures are rarely evaluated for preference, yield, and persistence under horse grazing. The objectives of this research were to evaluate horse preference, forage yield, and persistence of cool-season grass mixtures under horse grazing. Eight commercially marketed and four experimental perennial cool-season grass mixtures were planted in 2009 in a randomized complete block with five replicates and grazed by four adult horses during 2010, 2011, and 2012. All mixtures contained four to six cool-season perennial grass species. Specie density measurements were taken in each spring and fall, and yield was mechanically measured before each grazing period. After grazing, preference was determined by visually assessing percentage of forage removal on a scale of 0 (no grazing) to 100 (100% of vegetation removed). Data were analyzed using a mixed-model analysis of variance and liner regression. Horses preferred mixtures containing tall fescue, perennial ryegrass, Kentucky bluegrass, and timothy (P < .001). Horses had less preference for mixtures containing ≥30% orchardgrass (P < .001). Mixtures had similar (P = .11) forage yields that ranged from 6,100 to 7,082 kg ha⁻¹. After 2 years of grazing, orchardgrass and tall fescue increased; Kentucky bluegrass remained stable; and festulolium, meadow fescue, and perennial ryegrass had the greatest rate of decline in mixtures. Orchardgrass became the dominate species, regardless of initial percentage in the mixture. Mixtures containing tall fescue, perennial ryegrass, Kentucky bluegrass, and timothy should be planted in midwestern US horse pastures; however, mixtures will likely transition to tall fescue and Kentucky bluegrass–dominated pastures.     

天然草原青干草对农区洼地绵羊肉品质的影响

本研究旨在研究天然草原青干草对农区洼地绵羊肉品质的影响。选取4月龄洼地绵羊公羊27只,组间平均体重(20.0±0.5) kg,按随机区组原则分为3组(每组3个重复,每个重复3只):试验Ⅰ组饲喂天然草原青干草,试验Ⅱ组饲喂青贮玉米秸和花生秧,试验Ⅲ组饲喂青贮玉米秸和苜蓿,试验期105 d,其中预试期15 d,正试期90 d。结果表明,肉色、大理石花纹、pH、熟肉率等指标3个试验组间差异均不显著(P>0.05),失水率试验Ⅰ组显著低于试验Ⅱ组和试验Ⅲ组(P<0.05);剪切力试验Ⅰ组显著低于试验Ⅱ组(P<0.05)。粗蛋白质、粗脂肪、水分3个试验组间差异均不显著(P>0.05),粗灰分试验Ⅰ组显著高于试验Ⅱ组(P<0.05),试验Ⅰ组与试验Ⅲ组相比差异不显著(P>0.05)。氨基酸总含量3个试验组间差异不显著(P>0.05),鲜味氨基酸试验Ⅰ组显著高于试验Ⅱ组。综合研究表明,与农区秸秆饲料相比,天然草原青干草可以在一定程度上提高农区洼地绵羊羊肉的食用价值和营养物质含量,同时改善了羊肉风味,可在农区推广使用天然草原青干草。     

梨树省力密植栽培技术要点

随着人们生活水平的逐渐提高,对于物质生活质量的要求也越来越高,梨作为一种深 受人们喜爱的水果,其消耗量逐年增长。为了满足人们日益增长的物质生活需求,就需要不断 提高梨的产量和质量。因此,需要对梨树的生长发育进行深入的分析研究,在此基础上,采取有 针对性的省力密植栽培技术,进而有效提高当前梨树的种植水平,从而为梨的高产稳产提供可 靠保障。     

三种主养草鱼池塘沉积物-水界面碳通量的研究

为了探讨环境因子和底栖配养生物对碳通量的影响,采用实验室培养方法,测定并比较了不同混养模式下沉积物-水界面各形态碳的通量,监测了8月沉积物-水界面上覆水中各形态碳含量的昼夜变化。3种主养草鱼池塘的养殖模式为草鱼、鲢和鳙混养(GSB),草鱼、鲢、鳙和凡纳滨对虾混养(GSBL),草鱼、鲢、鳙和鲤混养(GSBC)。主要实验结果如下:(1)在养殖周期内,3种混养模式沉积物-水界面可溶性无机碳(DIC)通量范围为0.65~16.90 mg/(m²·d),可溶性有机碳(DOC)通量范围为0.16~13.49 mg/(m²·d),颗粒性有机碳(POC)通量范围为-2.29~3.32 mg/(m²·d);GSB和GSBC模式各形态碳通量均以8月最高,GSBL模式则以7月最高。(2)在养殖周期内,3种混养模式沉积物对DIC和DOC均表现为释放,而对POC在4-6月以吸收为主,其余时间表现为释放。(3)在养殖的中后期,3种混养模式的DIC、DOC和POC通量存在一定差异。其中,GSBL和GSBC模式中各形态碳通量值显著高于GSB模式(P<0.05)。(4)8月上覆水中DIC和DOC的含量在4:00达到最大值,POC含量则表现为GSBL模式在4:00达到最大值,12:00达到最小值,而GSBC模式在4:00达到最小值,12:00达到最大值。(5)各形态碳通量的变化与上覆水中的DO、pH呈显著负相关关系,而与水温呈显著正相关关系。