Effects of Elemental Sulphur and Farmyard Manure on pH and Salinity of Calcareous Sandy Loam Soil and Some Nutrient Elements in Tomato Plant

The objective of this study was to evaluate the effects of elemental sulphur （S） and farmyard manure on soil pH, EC and N, S, P concentrations of tomato grown in a calcareous sandy loam soil. For this purpose, a pot experiment was conducted in greenhouse conditions. Sulphur was applied at 0, 50, 100, 150, 200, 400 mg kg~ and farmyard manure at 0, 3 ton da^-1 to the soil. Three weeks after applications, tomato seedlings were planted and 8 weeks later, the plants were harvested to determine N, S, P concentrations and dry matter yield. Soil pH and EC were determined in the soil samples taken at 3 different periods. Effects of sulphur and farmyard manure applications were not significant on N, P concentrations and dry matter yield of tomato plant. S concentration of tomato plant was increased by sulphur alone. Soil pH was decreased and soil EC was increased in both 2^nd and 3^rd soil sampling period by the sulphur applications. As a result of farmyard manure application, soil pH decreased in the 2^nd soil sampling period but increased in the 3^rd soil sampling period. Also, soil EC was significantly increased in 1^st and 3^rd soil sampling period. Farmyard manure had no significant effect on S supply to tomato plant. The N：S ratio of tomato plant was decreased by sulphur alone. However, the sulphur with farmyard manure applications decreased N：S ratio in lesser extend compared to the S applications.     

Dynamic characteristics of CVT hydraulic system in speed ratio changing

Aiming at the hydraulic system of CVT (Continuously Variable Transmission), the transfer function of hydraulic system of CVT and the dynamic simulation model of this system based on AMESIM are built, and the characteristics of speed ratio response is simulated and calculated. The influences of spring constant, damping coefficient and mass of moving part on rising time, setting time and overshoot are analyzed. The result shows that the dynamic simulation model of this system is reasonable and will provide a basis and method for the optimization of CVT hydraulic system’s dynamic characteristics in the future.     

西双版纳热带植物园主要种植园区太阳辐射特征比较研究

利用2008—2009年间太阳辐射观测资料,分析了西双版纳热带植物园主要种植园区太阳辐射的变化特征,得出其变化及能量分配的相关规律。研究结果表明:在各植物园区,太阳辐射各分量均呈现单峰性变化,中午出现最大值;在具有高大树木、遮蔽较大的种植园区,太阳辐射各分量日总量与旷地的比值较小,在仅有低矮树木的百果园,其比值较大;西双版纳热带植物园植物种植园区,其形成的植物群落结构对太阳辐射的作用已经与原生林或次生林相当,具有明显林下辐射的特征,为植物园进行植物的迁地保护提供了较为原始的森林环境,减少植物的人为驯化,最大程度地保证原物种的遗传特征;不同园区辐射特征对植物迁地保护种植区域的选择提供了依据。     

新广州站三向张弦梁结构优化设计

基于运用APDL语言对新广州站工程三向张弦梁结构建立的参数化模型,利用一阶优化方法,对初始结构进行全构件截面和形状参数的综合优化.并在矢高和垂度确定的情况下,分别采用分级优化和综合优化分析了构件截面的合理取值.分析结果表明：矢高和垂度是三向张弦梁结构设计中极为重要的设计参数,新广州站三向张弦梁结构的最佳矢高为9.189 m,其垂跨比应不小于0.034,下弦垂度和上弦矢高的经济比值为0.22~0.23.上弦拱构件在结构中占的比重较大,可以通过减小拱截面的壁厚来降低结构的用钢量.并通过综合优化得到新广州站三向张弦梁的最佳梁弦刚度比为1.23×10-4     

不同浓度硼砂溶液对日光温室油桃坐果率的影响

日光温室栽培油桃普遍存在果实坐果率低、果个小、着色差等问题。微量元素硼能促进碳水化合物的合成和运转、刺激花粉粒的萌发和花粉管的伸长,提高坐果率。选用0.1%、0.3%、0.5%等3种不同浓度的硼砂溶液,在油桃初花期喷施叶片。结果表明,用硼砂溶液处理过的油桃坐果率都有所增加,浓度为0.1%的硼砂溶液坐果率最高,较喷清水提高了6.37个百分点。     

毛竹雨雪冰冻灾害主要影响因子的回归分析

应用逐步引入剔除法对毛竹受雨雪冰冻灾害程度的海拔、坡度、坡位、坡向、土壤深度、经营管理、竹林密度等因子与折断率、倒伏率、受损率分别进行多元线性回归分析,经检验F>F0.01,P<0.01,偏回归系数(bi)均为显著或极显著,说明回归方程均有极显著意义。通过标准偏回归系数(b′i)检验自变量的主次关系,表明影响折断率的主导因子及各因子的主次关系为海拔>土壤深度>坡位>坡度,海拔、坡度与折断率呈正相关,坡位、土壤深度与折断率呈负相关;影响倒伏率的主导因子及各因子的主次关系为竹林密度>坡度>经营管理>土壤深度,坡度、经营管理与倒伏率呈正相关,竹林密度、土壤深度与倒伏率呈负相关;影响受损率的主导因子及各因子的主次关系为土壤深度>坡度>海拔>竹林密度>经营管理,海拔、坡度、经营管理与受损率呈正相关,竹林密度、土壤深度与受损率呈负相关。说明回归模型可用于毛竹折断率、倒伏率和受损率预测。     

福建柯木类木材结构特征及其对干燥的影响

福建柯木类中的米槠、苦槠、红锥、高山锥和格氏栲的细胞构造具有共同特点。五种木材随着密度的增加导管细胞壁平均厚度变化不大,导管平均长度呈递增趋势。早晚材管孔的大小差异大,早晚材急变,导管的长度与孔径比值大;管孔的排列呈火焰状离散型,木射线宽窄不一,多数呈宽或较宽。导管的弦向直径与水分流密度呈正相关,导管长度越长,则水分传输性能越差,即径向干缩变化远小于弦向造成导管的收缩和扭曲,从而带来导管破裂,最终导致木材干燥缺陷。在木材干燥中这些特征造成木材内部温度梯度(t)/(x)或含水率梯度(w)/(x)显著增大时,对木材干燥速率有影响的水分流密度I_1值发生相应变化,只是变化值远小于木材表面向介质传递的水蒸汽量I_2,即I_1I_2。此现象更容易形成内外水分梯度差异,从而产生内应力,导致木材开裂翘曲和皱缩。此外,由于米槠等其早晚材导管的大小差异大,以及拥有宽窄不同的木射线,造成水份传导不均匀也影响木材干燥质量。     

Low leaf to fruit ratio delays fruit maturity of ‘Lapins’ sweet cherry on Gisela 5

Canopy leaf to fruit ratio (L:F) of 6-year-old ‘Lapins’ sweet cherry trees on Gisela 5 rootstock was manipulated at the end of stage II (38 DAFB) of fruit development. While control trees showed a L:F ratio of 0.7:1 without alteration, on other trees young fruit were manually removed to yield L:F ratios of 2:1 and 3:1, respectively. All leaves and young fruit on trees were counted 30 DAFB. The effect of altering the source–sink ratio of whole trees on sweet cherry fruit quality parameters (fruit increment, fruit mass, color, total soluble solids content, contents of individual sugars and organic acids) was evaluated in the study. High leaf area to fruit (LA:F) ratios influenced significantly darkest fruit color, higher fruit mass, higher total soluble solids content and higher ratio between sugars and acids, which corresponded to better ripening stage. Contents of glucose, fructose and sorbitol, but not sucrose, sum of individual sugars, and the content of malic acid differed significantly among fruit of the different treatments. Fruit of the most advanced maturity stage (treatment 3:1) had the highest quality. Each day of improved L:F ratio counts towards better sweet cherry fruit quality. The results show that low L:F ratio influenced prolonged ripening process and delayed fruit maturity of ‘Lapins’ sweet cherry.     

平贝母鳞茎离体培养研究

以MS为基本培养基,添加不同的激素配比进行平贝母鳞茎离体培养对比试验。结果表明:生长素NAA对形成愈伤组织有主导作用,添加量以0.6 mg/L较为合适,6-BA和KT对促进芽分化都能起主导作用,6-BA以0.4 mg/L为好,KT以1.0 mg/L为好,在生根阶段,添加2.0 mg/L的IBA较为理想。