择伐作业对常绿阔叶林乔木层树种结构及物种多样性的影响

研究4种不同强度择伐作业(弱度13.0%、中度29.1%、强度45.8%和极强度67.1%)对常绿阔叶林林分结构及乔木层物种多样性的影响结果表明,轻度与中度择伐对林分结构的影响较小,原林分乔木层优势树种的地位仍保持甚至略有提高;而强度择伐和极强度择伐则引起林分结构一定的变化,一些优势树种的地位削弱,而另一些树种的优势地位上升。但采伐作业不利于常绿阔叶林物种多样性的发展,尤其是林冠强度破坏对物种多样性的影响最大,而轻度与中度择伐作业有利于原有物种保持与恢复,这可能与不同强度择伐作业引起林地光照条件、温度和湿度等环境因子的不同变化有关。     

不同沙土比例对温室番茄侧枝扦插的影响

以温室中生长的“赛欧”番茄侧枝为试材,研究了沙土不同混合比例对侧枝扦插生长的影响,探讨促进番茄侧枝扦插的最佳沙土比例.结果表明:50％沙的处理效果较好,叶片数、株高、根系数、茎粗、根冠比和成活率等各项指标都好于其它处理.     

FSEC赛车电池热管理系统的优化设计

对于一辆纯电动赛车来说,电池性能的优劣很大程度上取决于电池的散热效率.本文以电池箱的热管理系统为研究对象,用CATIA精准建立电池箱的几何模型,并将其导入ANSYS ICEPAK进行网格划分,参数设置,模拟计算,得到数据,表明电池箱散热设计符合工作要求.     

杜英的扦插繁育技术

对杜英进行了不同枝条年龄、不同生根剂类型以及不同浓度的扦插繁育对比试验。结果表明:杜英以嫩枝扦插为佳,生根剂IBA+NAA等量混合、浓度200 mg/L生根效果最好。采用植物非试管苗智能化扦插设施进行扦插繁殖,具有生根快、生根率高的优点,生根率最高可达90.7%。     

植物生长调节剂对番茄扦插繁殖的影响

以“粉达”番茄的侧枝为试材,研究0、20、40、60、80、100、120 mg/L的吲哚乙酸、吲哚丁酸、萘乙酸和生根粉对番茄扦插繁殖的影响.结果表明:吲哚乙酸、吲哚丁酸、萘乙酸和生根粉的浓度分别为100、60、80、60 mg/L时,有利于番茄侧枝不定根的形成及成活率的提高.     

Vegetation,Hydrologic, and Erosion Responses of Sagebrush Steppe 9 Yr Following Mechanical Tree Removal

Land managers across the western United States are faced with selecting and applying tree-removal treatments on pinyon (Pinus spp.) and juniper (Juniperus spp.) woodland-encroached sagebrush (Artemisia spp.) rangelands, but current understanding of long-term vegetation and hydrological responses of sagebrush sites to tree removal is inadequate for guiding management. This study applied a suite of vegetation and soil measures (0.5 ? 990 m²), small-plot rainfall simulations (0.5 m²), and overland flow experiments (9 m²) to quantify the effects of mechanical tree removal (tree cutting and mastication) on vegetation, runoff, and erosion at two mid- to late-succession woodland-encroached sagebrush sites in the Great Basin, United States, 9 yr after treatment. Low amounts of hillslope-scale shrub (3 ? 15%) and grass (7 ? 12%) canopy cover and extensive intercanopy (area between tree canopies) bare ground (69 ? 88% bare, 75% of area) in untreated areas at both sites facilitated high levels of runoff and sediment from high-intensity (102 mm ? h^? 1, 45 min) rainfall simulations in interspaces (~ 45 mm runoff, 59 ? 381 g ? m^? 2 sediment) between trees and shrubs and from concentrated overland flow experiments (15, 30, and 45 L ? min^? 1, 8 min each) in the intercanopy (371 ? 501 L runoff, 2 342 ? 3 015 g sediment). Tree cutting increased hillslope-scale density of sagebrush by 5% and perennial grass cover by twofold at one site while tree cutting and mastication increased hillslope-scale sagebrush density by 36% and 16%, respectively, and perennial grass cover by threefold at a second more-degraded (initially more sparsely vegetated) site over nine growing seasons. Cover of cheatgrass (Bromus tectorum L.) was < 1% at the sites pretreatment and 1 ? 7% 9 yr after treatment. Bare ground remained high across both sites 9 yr after tree removal and was reduced by treatments solely at the more degraded site. Increases in hillslope-scale vegetation following tree removal had limited impact on runoff and erosion for rainfall simulations and concentrated flow experiments at both sites due to persistent high bare ground. The one exception was reduced runoff and erosion within the cut treatments for intercanopy plots with cut-downed-trees. The cut-downed-trees provided ample litter cover and tree debris at the ground surface to reduce the amount and erosive energy of concentrated overland flow. Trends in hillslope-scale vegetation responses to tree removal in this study demonstrate the effectiveness of mechanical treatments to reestablish sagebrush steppe vegetation without increasing cheatgrass for mid- to late-succession woodland-encroached sites along the warm-dry to cool-moist soil temperature ? moisture threshold in the Great Basin. Our results indicate improved hydrologic function through sagebrush steppe vegetation recruitment after mechanical tree removal on mid- to late-succession woodlands can require more than 9 yr. We anticipate intercanopy runoff and erosion rates will decrease over time at both sites as shrub and grass cover continue to increase, but follow-up tree removal will be needed to prevent pinyon and juniper recolonization. The low intercanopy runoff and erosion measured underneath isolated cut-downed-trees in this study clearly demonstrate that tree debris following mechanical treatments can effectively limit microsite-scale runoff and erosion over time where tree debris settles in good contact with the soil surface.     

非洲菊试管苗扦插生根育苗技术的研究

以非洲菊无根试管苗为试材，研究了扦插基质、生根粉（ABT）的浓度、生根粉（ABT）的处理时间对扦插生根育苗的影响，结果表明：生根粉浓度300mg/L、处理时间2h、培养基质腐殖土：河沙（2：1）处理的扦插苗生根效果最佳，其生根率可达92％以上，移栽成苗率高达97．73％，成苗快，幼苗健壮。     

不同扦插方式及栽培密度对紫薯“内17-71”产量的影响

为探究不同栽培方式对紫薯“内17-71”产量的影响,探索其最佳扦插方式及栽培密度,比较研究了不同扦插方式(正插3、5、7节和倒插3、5、7节)及不同株距(17、20、25、33、50 cm)对“内17-71”藤叶和薯块产量的影响。结果表明：无论正插或倒插处理,藤叶667m²产量均随扦插节位的增多而增加,其中正插5节、正插7节处理较高,分别为1 840.03、2 539.05 kg;且其薯块667 m²产量显著高于其他处理,分别为1 840.92、1 987.66 kg。随着栽培密度的提高,藤叶和薯块667 m²产量均表现出先增加后降低的趋势,而大中薯率则呈现下降趋势,其中株距25、20、17cm处理的薯块667m²产量分别为1 967.65、2 164.97、2 045.47 kg,显著高于其余处理。综合考虑种植成本及市场对大中薯的需求变化等因素,紫薯“内17-71”的栽培方式以株距20～25 cm、行距100 cm,正插5～7节为宜。     

乔砧苹果断根对根系及新梢的促控研究

通过早春断根后连续3年的观察,较完整地记载了苹果断根根系的再生状况及对新梢生长的影响。调查表明,盛果期乔砧苹果在发芽前断根,当年的抑梢效果不明显,第2年表现出显著的控长效果;距主干80cm左右断根后,根系再生复原期至少需2年以上,恢复期内对果实产量及品质无不良影响。     

短截、拉枝、刻芽对苹果枝条不同部位芽激素含量的影响

 为进一步了解修剪反应的生理基础,以‘富士’苹果（Malus × domestica Borkh.）3年生幼树为试材,在萌芽期研究不同修剪方式（短截、拉枝、刻芽、环刻）对1年生枝条不同部位芽中内源激素含量的影响。结果表明,未处理对照幼苗下部芽中生长素（IAA）和脱落酸（ABA）含量显著高于上部芽,玉米素核苷（ZR）和赤霉素（GA₃）含量明显低于上部芽。与对照相比,短截处理降低了枝条中部和下部芽中IAA和ABA的含量,相反,拉枝处理显著增加了枝条中部和下部芽中IAA和ABA的含量。另外,短截处理虽然提高了枝条中部和下部芽中GA₃和ZR含量,但未能改变枝条中部和下部芽中自身存在的含量分布梯度,而拉枝完全改变了枝条不同部位芽中自身存在的含量分布梯度。刻芽和环刻后芽体组织中GA₃、ZR、IAA等生长促进激素含量明显提高,而生长抑制激素ABA含量下降,刻芽打破了芽体中原有激素之间的平衡。