微波真空干燥对铁皮石斛品质特性影响的研究

本研究以新鲜铁皮石斛为原料,采用微波真空干燥方法干燥,通过测定铁皮石斛的多糖含量、色泽、多酚氧化酶（PPO）、水分分布状态、组成氨基酸以及多酚的DPPH?和?OH清除率,研究微波真空干燥对铁皮石斛品质特性的影响。结果表明：相比于新鲜样品,当微波强度为9 W/g,干燥后样品的多糖含量最高可达52.21%;氨基酸分析仪分析结果表明,微波真空干燥后铁皮石斛的总游离氨基酸和风味氨基酸含量显著提高。在微波强度9 、12 、15 W/g下,微波真空干燥的铁皮石斛的PPO活性分别在干燥16、12、6 min后不再存在,表明微波真空干燥能够在较短时间内钝化铁皮石斛的PPO活性,且微波强度越大时间越短。干燥过程的非酶促褐变主要由Maillard反应引起。低场核磁共振结果表明,自由水驰豫时间T₂₃和A₂₃均显著降低。自由基清除能力研究结果表明,铁皮石斛多酚仍具有较强的羟基自由基清除能力。通过观察干燥后样品的微观结构发现,随着微波功率密度的增大,样品孔状结构受到更严重破坏,微波强度越大,铁皮石斛的复水特性越好。     

Growth,yield and water productivity of dry direct seeded rice and transplanted aromatic rice under different irrigation management regimes

Sustainability of traditionally cultivated rice in the rice-wheat cropping zone (RWCZ) of Pakistan is dwindling due to the high cost of production, declining water resources and escalating labour availability. Thus, farmers and researchers are compelled to find promising alternatives to traditional transplanted rice (TPR). A field study was conducted in Punjab, Pakistan, in 2017 and 2018 to explore the trade-offs between water saving and paddy yield, water productivity and economics of two aromatic rice varieties under dry direct seeded rice (DDSR) and TPR. The experiment was comprised of three irrigation regimes on the basis of soil moisture tension (SMT) viz., continuous flooded (>−10 kPa SMT), alternate wetting and drying (AWD) (−20 kPa SMT) and aerobic rice (−40 kPa SMT), maintained under TPR and DDSR systems. Two aromatic rice verities: Basmati-515 and Chenab Basmati-2016 were used during both years of study. In both years, DDSR produced higher yields (13–18%) and reduced the total water inputs (8–12%) in comparison to TPR. In comparison to traditional continuous flooded (CF), AWD under DDSR reduced total water input by 27–29% and improved the leaf area index (LAI), tillering, yield (7–9%), and water productivity (44–50%). The performance of AWD with regard to water savings and increased productivity was much higher in DDSR system as compared to AWD in TPR system. Cultivation of DDSR with aerobic irrigation improved water savings (49–55%) and water productivity (22–30%) at the expense of paddy yield reduction (36–39%) and spikelet sterility. With regard to variety, the highest paddy yield (6.6 and 6.7 t ha⁻¹) was recorded in DDSR using Chenab Basmati-2016 under AWD irrigation threshold that attributed to high tiller density and LAI. The economic analysis showed DDSR as more beneficial rice establishment method than TPR with a high benefit-cost ratio (BCR) when the crop was irrigated with AWD irrigation threshold. Our results highlighted that with the use of short duration varieties, DDSR cultivation in conjunction with AWD irrigation can be more beneficial for higher productivity and crop yield.     

Role of basidiomycete fungi in the grapevine trunk disease esca

Phaeomoniella chlamydospora and wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known esca pathogens. However, the effect of their mixed infections and the sequence of infection on disease development is unclear. To determine the effects of single and co-inoculations on symptoms, potted Vitis vinifera ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha and the novel species Tropicoporus texanus. Basidiomycetes were isolated from vines with foliar symptoms of esca in California and Texas. In sequential co-inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations. Plants inoculated with P. chlamydospora either alone or in combination with a basidiomycete (in any sequence) did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, the appearance of large brown lesions, coupled with the absence of this wood symptom from control plants, suggests that C. radians, F. langloisii and T. texanus are pathogenic. Foliar symptoms resembling those of esca in the field (marginal and/or interveinal scorching, combined with red and/or yellow discoloration) were statistically more frequent among plants inoculated with F. polymorpha or T. texanus, either simultaneously or following P. chlamydospora, compared to single inoculations. Sequential co-inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.     

短轮伐期桉树人工林个体林木特征研究

利用广东高要和广西扶绥两地14个2~10年生桉树林分样地共287株样木,研究短轮伐期桉树人工林个体林木特征指标,并比较现有广西良种桉二元带皮和去皮材积公式估算个体林木材积的准确性,分析不同年龄、林分和径阶林木的出材率。结果表明:带皮和去皮林木的胸高形数为0.504±0.004 2和0.529±0.004 4、实验形数为0.410±0.002 4和0.427±0.002 7、形率为0.657±0.003 4和0.690±0.003 6、高径比为1.22±0.017和1.43±0.019。用广西良种桉二元带皮和去皮材积公式估算单株林木带皮和去皮材积与实际材积高度相关(r>0.99),但估算值普遍偏低,平均分别小3.7%和21.0%;尤以用带皮材积公式估算去皮材积比用去皮材积公式估计要准确,平均只小2.3%。如以6年生以上样地和尾径4 cm以上的去皮林木为实际出材,5个相关样地林分平均出材率为(73.3±4.31)%,最小为54.6%,最大为81.5%。     

CCA木材防腐剂活性成分检测方法比较试验

文章介绍了CCA木材防腐药剂中CuO、CrO3、As2O5等活性成分的常规化学分析方法,并与仪器分析方法进行了比较。结果表明,常规化学分析与仪器分析的结果相接近,两者之间的偏差很小,不需做修正便可应用于工业生产上。     

干制方法对枇杷叶总酚、黄酮等成分及抗氧化活性的影响

研究不同干制方法对枇杷叶总酚、黄酮等成分和抗氧化活性的影响,给生产实践提供技术依据和理论参考,以成熟枇杷叶作为试验材料,采用热风烘干（35℃、50℃、65℃、80℃）、自然晒干和阴干方式进行干制处理,用70%乙醇超声浸提,测定其黄酮、总酚、多糖含量及抗氧化活性。结果表明,不同干制条件下枇杷叶总酚、黄酮、多糖含量及抗氧化活性存在差异,其中阴干条件下所测成分含量及抗氧化活性最高,热风烘干条件下随着温度的升高,试验所测成分含量及抗氧化活性呈下降趋势。阴干可以较大程度地保留枇杷叶总酚、黄酮等成分及其抗氧化活性。在以干燥枇杷叶为原料,以总酚、黄酮等成分和抗氧化性为主的生产利用方面,应以阴干方法进行干制处理。     

火力楠人工林木材物理力学性质的研究

为掌握火力楠人工林木材的性质,为其木材利用提供科学指导,对火力楠人工林木材的主要物理力学性能指标进行了测定分析。结果表明,火力楠人工林木材的基本密度、气干密度以及全干密度平均分别为0.531、0.641 g·cm^-3和0.596 g·cm^-3,弦向、径向和体积气干干缩率平均分别为3.9%、2.7%和6.5%,对应的干缩系数平均分别为0.346%、0.239%和0.576%,差异干缩为1.444,属密度适中、干缩性小的一类木材;木材端面、弦面和径面硬度平均分别为5 989、4 847 N和4 829 N,抗弯强度、弹性模量、顺纹抗压以及冲击韧性平均分别为117.2 MPa（3级）,10.61 GPa（3级）、57.8 MPa（3级）和55 kJ·m^-2（2级）,综合强度达175 MPa,综合品质系数达3 295.7×10⁵ Pa,属高等级材。     

小径木梯形板锯刨机结构设计与研究

针对目前市面上加工小径木的机器加工精度低、效率不高、出材率低等问题,分析提高小径木梯形板出材率、加工效率及加工精度的设计方法,通过新的设计方法制定了新的加工工艺。结合工艺分析设计了小径木梯形板锯刨机的总体结构,可以对小径木梯形板进行锯切、粗刨、精刨加工。在对其核心组件锯切组件与刨削组件的加工原理进行分析的基础上,设计了锯切组件结构与刨削组件结构。通过导入锯切主轴SolidWorks的三维模型,利用ANSYS对其锯切主轴进行静力学分析,得到锯切主轴的应力、应变和变形云图,其中最大应力值为7.435 MPa、最大应变值为0.042 316 mm/m、最大变形量为0.002 178 8 mm,其强度、刚度及变形量均在许用范围内,仿真验证了锯切主轴的设计的合理性。     

木醋液在农业病虫草防控中的应用研究进展

为了开发木醋液作为优质生物农药的应用价值,本文归纳了不同原材料制作的木醋液在细菌真菌病害、病毒病、根结线虫病、害虫和杂草防除中的应用研究案例。总结了木醋液分别在病虫草防治中的作用：在适当浓度下,对真菌、细菌和根结线虫皆能有效抑制;作为助剂也能用于防治植物病毒病;对害虫具有驱避作用,浓度高时,直接的毒杀效果也很明显;对于作物田的部分杂草种类,木醋液具有被开发为生物除草剂的潜能。同时简单介绍了木醋液对有害生物的作用机理,指出了木醋液作为生物农药具有原材料来源广泛、广谱有效、环境友好、不易导致抗性发展等特点,其作为生物农药具有极大的应用价值。最后指出,在今后应用研发中应分馏纯化、组合复配木醋液产品,实现机制研究和产品标准化的综合目标。     

热风干燥温度对脱水白萝卜品质的影响

以"长春大根"白萝卜品种为试材,采用50、60、70、80、90、100℃的热风干燥处理1 cm×1 cm×10 cm的白萝卜条,研究热风干燥温度对脱水白萝卜品质的影响。结果表明,干燥温度为70℃时,脱水速率较快,脱水白萝卜色泽较白,感官品质、食用品质和复水性均较好,VC保留率较高。其次,干燥温度60℃时,脱水速率较慢,形态轻微变形、皱缩,食用品质略差。干燥温度低至50℃时,VC的保留率有所提高,但干燥时间延长,感官及食用品质均有所下降。干燥温度超过80℃后,干燥时间未显著缩短,脱水白萝卜褐变加重,感官品质、食用品质和复水性均变差,VC损失增加。