河西走廊苹果梨生态气候适应性与区划研究

试验研究表明河西走廊由于生态气候的不一致性,苹果梨具有明显的地域分布和时间特征,并表现出不同生长习性和品质属性,因气象要素分布的不均衡性,苹果梨生长发育年际间亦存在一定差异。甘肃省民乐县园艺场苹果梨果实生长发育动态呈“S”型曲线增长,据此计算出7月上旬至8月中旬果实生长率(CGR)最大,是果实膨大关键期,果实膨大适宜温度为15～21℃,全生育期需稳定通过≥7℃年积温2300～2800℃,品质形成期(9月上旬～10月上旬)要求凉爽的气候,在适温范围内日较差大,光照充足,有利于可溶性固形物含量的积累和着色,品质好。并依据影响苹果梨产量和品质的主要气象制约因子将河西走廊划分为5个气候适生区。     

基于疲劳损伤理论的果品振动损伤模型表征

疲劳振动是导致果品运输机械损伤的主要原因之一。基于Palmgren-Miner理论,结合果品振动损伤特征与外界振动激励的相关性,提出果品振动疲劳累积损伤模型与模型参数确定方法。以梨果实为研究对象,进行多种工况下的疲劳损伤振动与临界疲劳损伤振动试验,获得了水晶梨的振动疲劳常数;同时依据梨果实分级标准中的优等品损伤面积临界值,得出梨果实损伤激励加速度阈值,试验结果与理论分析吻合性高。研究结果为进一步认识果品振动疲劳损伤机理、进行果品振动缓冲包装提供了技术基础。     

不同果袋对苹果梨品质的影响

选择6种不同类型的果袋对苹果梨果实进行套袋处理,研究了套袋对果实品质的影响。结果表明,套袋改善苹果梨果实外观品质,果面光亮、洁净、着色好、果点变小且不明显;但套袋也会使苹果梨果实的内在品质有所降低,果实硬度、可溶性固形物含量、可溶性总糖含量、Vc含量降低。在6种果袋类型中,编号为D-1和D-5果袋处理的果实综合品质最佳。     

外源乙烯处理对黄冠梨果皮褐变和货架期品质的影响

为了避免黄冠梨果实在低温贮藏（0 ℃左右）条件下果皮褐变的发生,该研究采用5、20和100 μL/L外源乙烯对黄冠梨进行贮前处理,以0 ℃贮藏下无外源乙烯处理作为对照组,以采后恒温至30 ℃、逐步降温至0 ℃处理作为程序降温组。通过外源乙烯处理组与对照及程序降温组的对比,探讨采后外源乙烯处理对黄冠梨果皮褐变与果实品质的影响。结果表明,不同浓度的外源乙烯处理均能完全抑制褐变的发生,且表皮无伤害,而程序降温组的发病指数为10%,对照组则高达37.6%。货架期结束时（6 d）外源乙烯处理组的果实硬度与对照组差异显著（P < 0.05）。外源乙烯各处理组果实含水率均高于对照及程序降温组（P < 0.05）,利用低场核磁共振技术检测发现对照组自由水含量最高,5和100 μL/L外源乙烯处理组自由水含量较低。与对照组和程序降温组比较,外源乙烯处理对黄冠梨果实中可溶性固形物、可滴定酸、可溶性糖和抗坏血酸等果实品质指标都能起到提高或者维持的效果,其中5 μL/L处理浓度的效果较优。研究结果表明,贮前外源乙烯处理是一种既能抑制黄冠梨果皮褐变又能保持果实货架期品质的高效、简便的技术。     

基于随机森林算法和气象因子的砀山酥梨始花期预报

准确预报始花期是制定砀山酥梨花期管理措施和赏花活动方案的重要基础。该研究利用1983—2018年砀山酥梨始花期的定位观测物候数据和平行观测的气象资料,采用线性趋势法,揭示始花期演变趋势;采用相关分析,筛选影响始花期的关键气象因子,依据不同预报日期构成特征变量集;采用随机森林算法（Random Forest, RF）,自3月11日开始预报到3月25日终止预报,每日训练1个预报模型。结果表明,1）1983－2018年始花期呈极显著提早发生趋势,每10 a约提前2.750 d（P＜0.001）。2）16个逐日气象预报模型中,共计有200个气象因子与始花期早迟密切相关,相关系数在0.469～0.789之间;各气象预报模型的训练集与测试集的平均正确率（Nd）分别为92.9%和75.5%、平均均方根误差（RMSE）分别为1.693～2.870和2.240～7.237、平均决定系数（R2）分别为0.891和0.701。3）2019年试验预报中,提前15 d准确预报出当年始花期。该文研究表明RF在梨树始花期逐日气象预报中有一定业务应用潜力,预报准确率基本满足气象服务需求。     

高压脉冲电场对鲜榨梨汁的杀菌效果及其对产品品质的影响

为了采用非热杀菌技术以生产高质量的果汁,研究了高压脉冲电场（PEF）对梨汁的杀菌效果及其对产品品质的影响。结果表明,当电场频率、电场强度和处理时间、温度分别为200 Hz、30 kV/cm和240 μs、10℃时,梨汁中接种的大肠杆菌、酿酒酵母的数量分别下降4.6、2.7个数量级。温度具有辅助杀菌效应,相同频率和场强下处理时间200 μs,当样品温度从10℃上升致40℃时,大肠杆菌致死率提高了1.4个数量级,酿酒酵母致死率提高了2.0个数量级,未接种鲜榨梨汁的细菌致死率提高了2.0个数量级,霉菌酵母致死率提高了1.0个数量级。PEF处理后梨汁理化性质、营养成分比热处理更接近原样。气相色谱－质谱（GC-MS）对梨汁风味物质进行检测的结果表明,梨汁中含量最多的挥发性风味物质为酯类,与传统热处理相比,PEF处理对梨汁风味物质的影响较小。因此脉冲电场不仅有较好的杀菌作用,并且最大限度地保证了梨汁的品质。     

不同新型作用机制杀菌剂对梨树主要病菌毒力及防治流程应用

 为明确多种新型作用机制杀菌剂与引起梨树褐斑病、黑星病、白粉病等病原菌的有效对靶关系及制定梨树主要病害防治流程,采用菌丝生长速率法、离体叶片法与田间药效方法研究新型杀菌剂对靶标病原菌的毒力、对靶标病害的防效及其田间有效应用,建立替代梨树主要病害传统化学杀菌剂的防治流程技术。结果显示,双胍三辛烷基苯磺酸盐在离体叶片法下对褐斑病的防效大于85%,田间药效验证3次用药后7 d防效大于85%、30 d防效大于80%、90 d防效仍大于60%,兼治轮纹病菌其毒力EC₅₀值均小于1 μg·mL^-1。双胍三辛烷基苯磺酸盐、辛菌胺醋酸盐、吩嗪α-2羧酸在离体叶片法下对黑星病防效大于90%且毒力EC₅₀值小于1 μg·mL^-1;田间药效验证1次用药后7 d防效大于80%、30 d防效仍大于75%。噻肟菌酯、硝苯菌酯、丙硫菌唑在离体叶片法下对白粉病的防效大于85%;田间药效验证3次用药后7 d铲除效果大于70%、30 d仍大于60%。丙硫菌唑对黑斑、轮纹病菌毒力EC₅₀值均小于1 μg·mL^-1;吩嗪α-2羧酸同时对褐斑、黑斑、轮纹病菌毒力EC₅₀值小于1 μg·mL^-1。针对梨树主要病害发生期,选用新型杀菌剂替代传统杀菌剂制定防治技术流程,其综合防效达到88.94%。不同新型作用机制杀菌剂在防治梨树主要病害上的应用,能够降低抗药性产生,同时达到有效防治的目的。     

蜜梨NFC果汁清咽功能评价的动物试验研究

为了评价蜜梨NFC果汁的清咽功能,通过大鼠棉球植入、大鼠足趾肿胀、小鼠耳廓肿胀3种动物模型试验,研究不同剂量的蜜梨NFC果汁对大鼠肉芽肿重、大鼠足趾肿胀率、小鼠耳廓肿胀率和动物体重增长的影响。结果表明,与阴性对照组(CK)相比,高剂量组(T3)大鼠肉芽肿净量减少23.47%,差异极显著;T3致炎后2、4 h和中剂量组(T2)致炎后4 h的大鼠足趾肿胀率分别减少14.5%、20.4%和16.5%,且差异显著;T2、T3小鼠耳廓肿胀率分别减少24.1%和27.8%,差异显著;而高、中、低3个剂量组的大鼠或小鼠体重增长量在试验期间均无显著差异。因此,大鼠棉球植入、大鼠足趾肿胀和小鼠耳廓肿胀试验结果均为阳性,且蜜梨NFC果汁对大鼠或小鼠的正常生长无影响,表明蜜梨NFC果汁动物试验结果为阳性,具有清咽功能。研究结果可为蜜梨清咽功能的开发利用提供参考依据。     

Field testing of different synthetic attractants for mass trapping of common European cockchafer (Melolontha melolontha [L.], Coleoptera,Scarabaeidae) adults

Between 2012 and 2014, we tested the efficacy of different synthetic attractants for the purpose of massive trapping of common European cockchafer adults (Melolontha melolontha). The research took place in three different locations in Slovenia (Otlica, ?rni Vrh nad Idrijo, Cesta nad Ajdov??ino) during flight periods of adult beetles. In the period 2013–2014, we used, on the basis of the preliminary test results (2012), the following chemicals: toluquinone, cis–3–hexen–1-ol, ethyl acetate, toluquinone?+?cis–3 hexen–1-ol, and ethanol as a control. M. melolontha adults were most abundant in the location ?rni Vrh nad Idrijo; the traps in this location caught 18 times more of them than those in the first location and more than six times more than those in the third location. Male insects accounted for 73 to 87% of the trapped specimens. We confirmed the highest efficiency of cis–3–hexen–1-ol in 2013 (43.25?±?0.08 males/trap), as well as in 2014 (15.00?±?0.14 males/trap). On the basis of the trapped adult common European cockchafers and the simple economic analysis of applying different synthetic substances for attracting them, we found that independent application of cis-3-hexen-1-ol is the most efficient and cost-effective option for attracting the studied insect pest. Consequently, we recommend it as an attractant in the traps for massive trapping of adult common European cockchafers.     

Reliability of an expert-based runoff and erosion model: Application of STREAM to different environments

During the last decades, the European loess belt has been confronted with a significant increase in environmental problems due to erosion on agricultural land. Spatially distributed runoff and erosion models operating at the catchment scale are therefore needed to evaluate the impact of potential mitigation measures. Expert-based models offer an alternative solution to process-based and empirical models, but their decision rules are only valid for the local conditions for which they have been derived. The STREAM model, which was developed in Normandy (France), has been applied in two Belgian catchments having a similar soil texture, as well as in a catchment of southern France differing by soil, land use and climate characteristics. The performance of hydrological models can be assessed for instance by calculating the Nash–Sutcliffe efficiency criterion (E_NS). When applied to Belgium, the model results are satisfactory to good after an adaptation of the decision rules (0.90 < E_NS < 0.93 for runoff predictions and 0.85 < E_NS < 0.89 for erosion predictions). Given the important environmental differences between Normandy and southern France, the model rules were also adapted for application in the latter environment. Unfortunately, the quality of runoff predictions was insufficient to simulate erosion in southern France. In conclusion, STREAM is a reliable model providing satisfactory runoff and erosion predictions in the regions where hortonian overland flow dominates. Nevertheless, an adaptation of decision rules based on local multi-scale (plot, field, catchment) data is needed, before running the model. STREAM can then serve as a decision support tool to design for instance flood control measures.