龙眼长跗萤叶甲成虫空间分布型的研究

通过调查分析,明确了龙眼长跗萤叶甲(Monolepta occifuvis Gressitt et Kimoto)成虫在龙眼园的空间分布型为聚集分布,在田间调查龙眼长跗萤叶甲成虫种群数量时可采用棋盘式、直线跳跃式或五点式抽样,其中以棋盘式较好。通过Iwao—Kuno理论抽样数学模型确定了在一定水平下的理论抽样数。     

壳聚糖对黄瓜品质和产量的影响

用不同处理方式研究了不同质量浓度的壳聚糖对黄瓜品质和产量的影响。结果表明 ,1 5mg·mL-1 壳聚糖浸种对增加黄瓜可溶性蛋白质、游离氨基酸、可溶性糖含量 ,以及降低其纤维素含量的效果最佳 ;2 0mg·mL-1 壳聚糖浸种对增加维生素C含量效果最佳。此外 ,在喷叶处理中 ,增加可溶性蛋白质的最佳浓度是 0 2mg·mL-1 ,其他品质改善的最佳浓度为 0 1mg·mL-1 。壳聚糖处理能明显提高黄瓜的产量     

湖南省区域建设用地集约利用评价及空间差异研究

以湖南省13个参评地级市为样本,参照《城市建设用地节约集约利用评价操作手册》构建区域建设用地集约利用评价指标体系,通过建设用地集约利用的定性分析和定量评价来综合分析参评城市的建设用地集约利用评价水平。结合数轴法和聚类分析法确定各参评城市的土地集约利用等级,并分析各参评市建设用地集约利用现状和空间格局分布特征。研究结果表明:建设用地集约利用水平的区域差异显著,在空间分布上表现为湖南省东北高西南低,且北部地区整体优于南部地区;评价单元的地理区位、经济水平、交通等基础设施情况导致建设用地集约利用水平空间差异;各参评城市建设用地集约利用水平的制约因素存在显著差异。根据评价结果,应强化建设用地管理工作,提出相关措施建议来实现各区域人口、经济和建设用地的协调发展。     

知识经济条件下农业院校科技服务体系创新探讨

论述了知识经济条件下农业院校科技服务体系创新的意义,分析了我国农业科技服务体系的现状与存在的问题,探讨了知识经济条件下农业院校科技服务体系创新的实现途径,提出了确立农业科技服务创新的理念、探索农业科技服务创新机制、创新农业科技服务模式和提升农业科技服务的手段。     

大麦种质对叶斑病的抗性鉴定与评价

 由麦根腐平脐蠕胞菌引起的叶斑病在世界各大麦种植区均有发生,严重影响大麦的产量和品质。选育和应用抗性品种是防控该病害最有效的策略,然而可利用的抗源非常有限。在本研究中对中国233份具有代表性的大麦种质资源进行成株期抗叶斑病田间人工接种鉴定,发现只有垦啤麦5号等10份材料对3个供试菌株都表现抗病,仅占供试材料的4.3%。另外对37份国内外重要的叶斑病抗源材料进行苗期及成株期抗叶斑病鉴定,结果显示成株期抗叶斑病材料所占比例为41%~46%,苗期抗性材料所占比例为50%~64%,其中ND17293等11份材料在苗期和成株期对3个菌株均表现为抗病,可作为抗源继续加以利用;基于上述鉴定结果,进一步分析发现供试大麦苗期对三个菌株的抗病比例均高于成株期抗病比例,说明大麦在不同生育期对叶斑病的抗性存在较大差异。另外发现大麦对B. sorokiniana不同致病类型的抗性也存在明显的专化性。     

Silicon promotes seedling growth and alters endogenous IAA,GA3 and ABA concentrations in Glycyrrhiza uralensis under 100 mM NaCl stress

A sand culture experiment was conducted to determine the effects of Si on the growth and endogenous hormone concentrations (indole-3-acetic acid [IAA], gibberellic acid [GA₃], and abscisic acid [ABA]) in Glycyrrhiza uralensis seedlings under 100 mM NaCl stress. Si time-dependently improved the growth and increased the biomass of seedlings, and the effect was greater at 20 days than that at 10 days after Si treatment. The effects of Si on the growth parameters and biomass were dependent on Si concentration, that is, these parameters increased with increasing Si concentration. Si also increased the levels of endogenous hormones in G. uralensis seedlings in a concentration-dependent manner. The effects on IAA and GA₃ increased with increasing Si concentrations, and the effect on ABA was higher at 2 mM Si than that at the other Si concentrations. Furthermore, the effects of Si on IAA and GA₃ were greater at 10 days than those at 20 days after the treatment, whereas the effect on ABA was greater at 20 days than that at 10 days after the treatment. Hence, Si can regulate the concentrations of endogenous hormones and correspondingly improve the growth of G. uralensis seedlings under salt stress condition.     

Adventitious shoot regeneration and Agrobacterium tumefaciens-mediated transformation of leaf explants of sweet cherry (Prunus avium L.)

Sweet cherry (Prunus avium L.) remains recalcitrant for genetic transformation due to the lack of efficient plant regeneration systems via organogenesis or somatic embryogenesis. In this study, in vitro shoot cultures were derived from a single mature embryo (open pollinated) of ‘Selah’ sweet cherry. Leaf explants were cultured on Woody Plant Medium supplemented with different plant growth regulators to induce shoot regeneration. The optimal regeneration at a frequency of 32.5% and an average of 1.1 shoots per explant occurred on the medium containing 4.54 µM thidiazuron (TDZ) and 2.95 µM indole-3-butyric acid (IBA). Transient transformation showed an efficient delivery of the β-glucuronidase (GUS) reporter gene (gusA) using Agrobacterium tumefaciens strain EHA105. Under the optimal gene delivery conditions, stable transformations were conducted using pGA643 and pBI-VcFT containing a blueberry FLOWERING LOCUS T (VcFT). A total of 500 leaf explants, 250 for each construct, were used for transformation. After 10-week selection, three leaf explants transformed with the pGA643 produced four kanamycin-resistant shoots, in which stable integration and expression of the nptII were confirmed by Southern blot and RT-PCR analysis, respectively. This study demonstrated that it was possible to produce stable transgenic sweet cherry using Agrobacterium tumefaciens-mediated transformation of leaf explants.     

鼓式制动器三维热—机耦合温度场仿真

通过对鼓式制动器惯性制动时蹄鼓摩擦接触状态分析,考虑接触副摩擦因数温度特性,以EQ1208车后桥鼓式制动器为例,对建立的鼓式制动器热-机耦合三维有限元模型进行了惯性制动工况数值仿真,得到了鼓式制动器耦合瞬态温度场仿真结果.A测试点温升试验结果与仿真结果对比,两者变化趋势相同,且吻合较好.对在惯性制动工况下的鼓式制动器温升主要影响因素(车速和道路坡度)进行了仿真分析.     

机载式农田三维地形测量系统设计与试

设计了一种机载式农田三维地形测量系统.该系统主要由激光测量接收器、GPS接收机、控制器和液压系统等组成,除了可以进行地形测量外,系统还可以实现激光平地作业.其测量原理是利用测量接收器获取测量点的高程信息,利用GPS接收机获取测量点的平面位置信息,将两者在控制器中进行数据融合,从而得到测量点的三维地形信息.在田间试验条件下,对机载式农田三维地形测量系统进行了不同行进速度下的试验研究,并与采用定点测量方法获取的数据进行了比较.试验结果表明,该系统在低速行驶条件下与定点测量方法具有较好的一致性.