不同形态氮素对种植大豆土壤中微生物数量及酶活性的影响

采用框栽试验方法,研究6种不同形态氮素[生物固氮(N0)、硝态氮(N1)、铵态氮(N2)、氨基酸态氮(N3)、蛋白态氮(N4)和酰胺态氮(N5)]对种植大豆土壤中微生物数量及土壤酶活性动态变化的影响。结果表明:各大豆生育期内真菌、细菌、放线菌数量和土壤脲酶、蔗糖酶活性对不同形态氮素的反应不同;三大菌群在组成上以细菌数量占绝对优势,数量上均在花期时达到峰值,即均随着大豆生育期的推进呈单峰曲线变化;花期不同形态氮处理下的土壤微生物总数量有差异,具体表现为N5N3N2N1N4N0。土壤多样性指数的变化趋势随着生育期的推进呈缓慢下降趋势,与土壤微生物数量的变化趋势不一致,因此,评价土壤生物多样性指数应将两者结合起来。土壤脲酶和蔗糖酶活性随着生育期的推进亦为单峰曲线变化趋势,但脲酶与蔗糖酶活性的变化趋势不同,其高峰期出现在鼓粒期。     

Dwarf mistletoe effects on soil basidiomycete community structure, soil fungal functional diversity, and soil enzyme function: Implications for climate change

We used a combination of molecular, culture and biochemical methods to test the hypothesis that severe infection of pine by dwarf mistletoe (genus Arceuthobium) has significant effects on structure and function of soil fungal communities, and on carbon cycling in soils. PCR and DNA sequencing of the basidiomycete communities in paired blocks of uninfected and infected trees revealed: (1) that the top, organic soil layer in this system is inhabited almost exclusively by ectomycorrhizal fungi; (2) no difference in species richness (6 species core⁻¹ in both) or Shannon-Wiener evenness (0.740 and 0.747 in uninfected and infected blocks respectively), however Shannon-Wiener diversity was significantly greater in infected blocks (1.19 vs 1.94 in uninfected and infected blocks respectively, P < 0.05); (3) significant differences in basidiomycete species composition, with nearly complete absence of two system co-dominant Russula species in infected blocks, and replacement of one co-dominant Piloderma species with another in infected plots, indicating physiological variability within the genus. Soil fungal physiological diversity measured using the Fungilog system was significantly greater in terms of both number of carbon substrates used by culturable soil fungi (both ascomycetes and basidiomycetes) in infected blocks, and the rate at which these substrates were used. Soil enzyme assays revealed greater laccase, peroxidase, and cellulase activities in soils associated with infected trees. Thus, event cascades associated with severe dwarf mistletoe infection not only significantly affected soil fungal species composition and increased species diversity, but also impacted on carbon-related function and functional diversity. Given the geographic range of this pathogen, and forecasts that epidemics of this disease will increase in range in severity with global climate change, these effects have the potential to significantly impact local and global carbon budgets.     

桃树树体改造及长枝修剪关键技术

着重介绍桃树树体结构改造、枝组调整和处理以及长枝修剪的优点、要领,总结出桃树树体改造和长枝修剪应注意的问题等。     

寒地苹果矮化密植高效建园技术的研究

在我国寒地以GM_2 56做中间砧 ,进行苹果矮化密植栽培 ,与乔化稀植栽培相比 ,效益可提高 9倍。其关键的建园技术是 :营养面积以每株 6m2 较合适 ;树盘盖膜可提高定植成活率与加快生长 ;先定植砧木后高接生产品种 ,可提高定植成活率 ,促进芽萌发 ,提高嫁接率和早期产量。     

黑果腺肋花楸不同树形与主枝数对产量的影响

该文通过抽样调查和统计分析,充分论证了黑果腺肋花楸采用丛状树形明显优于疏散分层形和扇形,当主枝数达19～22条时单位面积产量最高。     

雌雄蛹自动分选机的研制

雌雄蚕蛹分选是制造优质蚕种的重要环节。依据雌雄蛹体重量和体形大小存在明显差异的特点 ,研制成功三段式雌雄分选机。经生产测试 ,每小时可分选 135 96kg茧的蚕蛹 ,分选雌雄蛹的误鉴率平均为 3 18% ,比人工分选的准确率高 ;通过调节分选孔的大小 ,准确率可达 99 5 %以上 ;在复眼着黑后分选对蛹体无损伤。机械操作简易 ,符合生产要求     

科尔沁草地植被特征

科尔沁草地有维管束植物１６４２种，隶属１２４科，５４属，其中菊科，禾本科，豆科，蔷薇科合计１５６属，５９１种，分别占全地区总属数，总种数的２８．８４％和３５．９９％，全部植物属于１５个区系成分，以达乌尔－蒙古成分起主导作用。多年生草本植物（１００９种）是构成科尔沁草地植被的主体，中生植物（１１４１种）居优势地位，沙生植物和盐生植物的广泛分布也是本地区植被的重要特征，草原植被水平分布规律基本上呈西北     

日本设施果树的树形结构与光能利用研究进展

通过留学期间对日本设施果树树形结构与光能利用特性的调查分析与研究 ,结果表明 :日本设施果树的树形结构研究始终是围绕高光效、高质量、易管理这三个中心 ,生产上重点在推广单层薄叶幕结构的平棚树形 ,X形、H形、Y形和三主肋骨形及其改良形等高效优产树形已在不同果树上广泛应用。其中Y形非常适合乔木果树的集约化矮密植栽培 ,符合优质、高产、高效农业的发展方向 ,有广泛普及价值 ,未来可能成为除葡萄外多种果树的的通用树形。此类树形结构的突出特点是 :枝叶单层水平分布 ,叶幕薄 ,离地高 ,生态环境优越 ,通风透光好 ,病虫害少。结果均匀整齐 ,下垂果多。果实形正、色佳、味甜、质量好 ,商品档次高。树冠覆盖率和有效生产区高达10 0 %。枝叶生长缓和 ,树势容易控制 ,枝梢夏季管理省工。各器官生长发育状态与节奏好 ,长停交替按次有序 ,营养分配协调合理。而且作业空间大 ,机械行走方便。建议我国因地制宜研究选用     

土壤农化性状对土壤酚类物质积累的影响

土壤中酚类物质是土壤有毒物的主要来源。它在土壤中能否积累取决于土壤肥力和土壤酸碱度。三耕土的C/N和全N量与头耕土相近,但前者腐殖质难于形成,土壤容易中毒。笔者认为,这是土壤中N素形态影响的结果。因此必须注重土壤培肥,使地力常新壮。     

自然式生态农业观光园的开发与研究

通过对生态农业观光园的由来及发展概况的介绍,指出了自然式生态农业观光园开发的原因;提出了自然式生态农业观光园总的开发原则;说明了自然式生态农业观光园开发的前提条件,以及自然式生态农业观光园的布局原则;同时指出了自然式生态农业观光园在开发中应注意的问题;最后指明自然式生态农业观光园的发展趋势,并说明了生态农业观光园具有广阔的发展前景。