Natural enemies and seasonal abundance of the blackmargined aphid (Monellia caryella) in pecan orchards in Israel

The blackmargined aphid,Monellia caryella (Fitch), exhibited a seasonal pattern with early and late peaks of the population in pecan orchards at Newe Ya’ar in the Yizre’el Valley. A similar pattern was not observed at Kibbutz Sede Eliyyahu in the Bet She’an Valley, where there was a single peak, late in the season. The occurrence of natural enemies indicated that spiders and lacewing eggs were the predators most commonly associated with population fluctuations of the aphid. In most cases the rate of increase of the blackmargined aphid was highest late in the season.     

薄壳山核桃种质资源的开发利用

结合薄壳山核桃的自然分布和世界发展现状,综述了其在我国引种的历史与发展,并根据薄壳山核桃的特点,结合华东地区社会、经济、生态的需求,提出了其产业化发展的模式。     

AdaBoost classifiers for pecan defect classification

One of the constraints in the adoption of machine vision inspection systems for food products is low classification accuracy. This study attempts to improve pecan defect classification accuracy by using machine learning classifiers: AdaBoost and support vector machine (SVM). X-ray images of good and defective pecans, 100 each, were segmented and features were extracted. Twenty classification runs were made to adjust parameters and 300 classification runs to compare classifiers. The Real AdaBoost classifier gave average classification accuracy of 92.2% for the Reverse water flow segmentation method and 92.3% for the Twice Otsu segmentation method. The Linear SVM classifier gave average classification accuracy of 90.1% for the Reverse water flow method and 92.7% for the Twice Otsu method. Computational time for the classifiers varied by two orders of magnitude: Bayesian (10⁻⁴ s), SVM (10⁻⁵ s), and AdaBoost (10⁻⁶ s). AdaBoost classifiers improved classification accuracy by 7% when Bayesian accuracy was poor (less than 89%). The AdaBoost classifiers also adapted well to data variability and segmentation methods. A minimalist AdaBoost classifier, more suitable for real time applications, using fewer features can be built. Overall, the selected AdaBoost classifiers improved classification accuracy, reduced classification time, and performed consistently better for pecan defect classification.     

不同品种美国山核桃叶绿素荧光特性的比较

研究了不同品种美国山核桃的叶绿素荧光特性和光合效率,旨在为其优良品种选择和高效栽培提供科学依据。以8个美国山核桃品种为试材,田间测定了其叶绿素荧光参数及叶片基本性状。结果表明,不同品种间的PSⅡ原初光能转化效率(primarily photochemical efficiency ofphotosystem Ⅱ,Fv/Fm)、PSII潜在活性(potential activity of photo-systemII,Fv/F0)、非光化学猝灭系数(non-photochemical quenchingcoefficient,qN)均存在显著或极显著差异,其中金华1号、UM9-82个品种的Fv/Fm值分别为0.809、0.796,Fv/F0值分别为4.266、3.910,均显著高于其它品种,表现出良好的光合性能;光合量子产额(effective quantum yield of photosystem Ⅱ,Yield)和光化学猝灭系数(photochemical quenching coefficient,qP)未达显著差异。不同品种叶片比叶重和叶绿素含量及各组分均存在显著差异。相关分析表明,叶绿素及各组分含量与Yield均呈显著或极显著负相关。据此,湖南地区要引种外地具有优良光合性能的美国山核桃作为栽培品种时,在供试8个品种中,金华1号、UM9-82个品种可为首选品种。     

山核桃破壳机的设计

设计了一种基于挤压方式的山核桃破壳机械。特殊设计的螺旋碾桶和轧辊配合,实现山核桃破壳。选择轧楞倾角、碾桶螺距和轧辊转速为正交试验的3个因素,并通过极差分析和方差分析,确定轧楞倾角为15°、轧辊转速20 r/m in和碾桶螺距为2倍栅格宽度为其最优组合。试验结果表明,该设备破壳率99.4%、碎仁率为0.6%,改善了破壳质量,并提升了山核桃破壳机械化生产水平。     

薄壳山核桃优良品种及其特性研究

薄壳山核桃品种繁多,笔者搜集并整理了大量品种的特性数据,并选取几个与栽培密切相关的重要特性在本文中分述。主要从原产地分布、开花类型、果熟期、坚果品质、始果年龄、丰产稳产性、抗病性以及适宜地区等方面对美国山核桃品种进行概述,并分别举例。     

薄壳山核桃良种试验初报

薄壳山核桃品种——马汉、威斯顿、特贾斯、钟山25号、肖肖尼的引种试验表明:5个品种在江苏泗洪地区生长结果正常,果实经济性状好,坚果具有个大、壳薄、出仁率高等特点,因而这5个薄壳山核桃品种适合在江苏淮北地区推广。     

A rapid method to monitor fungicide sensitivity in the pecan scab pathogen, Fusicladium effusum

Commercial production of pecans in the southeastern U.S. relies on fungicide applications to control scab, caused by Fusicladium effusum. Under intense disease pressure, 10–15 applications may be made per season and the potential development of fungicide resistance is a major concern. A rapid method was developed to determine sensitivity of the pathogen to protectant chemicals based on conidia germination, and to fungicides active on post-appressorial pathogen stages based on micro-colony growth. This method uses conidia transferred directly from lesions to fungicide-amended media. Using this method, sensitivity profiles were determined for isolates from three non-treated orchards with little or no fungicide use histories and from 33 commercial orchards in 2008 with a history of fungicide use. Compared to the non-treated orchards, significant reductions in in vitro sensitivity were detected in 20 orchards to fentin hydroxide, in 4 orchards to dodine, in 6 orchards to thiophanate-methyl and in 20 orchards to propiconazole. The novel methodology will be useful for monitoring fungicide sensitivity of F. effusum populations and evaluating resistance management programs in commercial pecan orchards.     

Changes in ultraviolet-B and visible optical properties and absorbing pigment concentrations in pecan leaves during a growing season

UV-B (280–320 nm) and visible (400–760 nm) spectral reflectance, transmittance, and absorptance; chlorophyll content; UV-B absorbing compound concentration; and leaf thickness were measured for pecan (Carya illinoensis) leaves over a growing season (April–October). Leaf samples were collected monthly from a pecan plantation located on the Southern University Horticultural Farm, Baton Rouge, Louisiana. The leaf spectral reflectance and transmittance were measured from 280 to 760 nm using a high-accuracy UV-Vis spectroradiometer with an integrating sphere. The spectral absorptance was calculated based on the reflectance and transmittance percentages. Total UV-B absorbing compounds concentration (A_{280–320 nm} (cm⁻²)), chlorophyll content, and leaf thickness were related to the leaf optical properties. The patterns of the spectral distributions of optical properties over the growing season, effects of leaf age on the measured parameters, and their relationships were determined. Leaf optical properties were significantly affected by leaf age and the effects were more dramatic in the visible spectral region than in the UV-B region. Within the UV-B spectral region, leaf reflectance ranged between 4.27% (April) and 8.29% (July), transmittance between 0.01% (June) and 0.05% (April), and absorptance between 91.70% (July) and 95.68% (April). Within the visible spectral region, leaf optical properties changed significantly with the wavelength and leaf development. The visible spectral reflectance and transmittance had maxima at 555 nm and minima at 680 nm, and increased sharply afterwards. The highest visible spectral reflectance and transmittance occurred in the newly developed leaves, whereas the visible spectral absorptance increased with leaf maturation. Leaf chlorophyll content, thickness, and UV-B absorbing compound concentration significantly increased during leaf development (April–July). Correlation and regression analyses indicated that leaf chlorophyll content was a strong predictor of the green light reflectance, transmittance, and absorptance. The strongest predictors of UV-B reflectance were leaf thickness and leaf UV-B absorbing compound concentrations.     

不同品种薄壳山核桃光合及快速叶绿素荧光诱导动力学特性

以‘Pawnee’、‘Mahan’、‘Stuart’、‘Kanza’和‘Jinhua’5个薄壳山核桃品种结果树为研究对象,对其光合特性及快速叶绿素荧光诱导动力学特性差异进行了研究。结果表明,不同品种薄壳山核桃的光合特征参数存在一定差异,‘Stuart’光合能力最弱,‘Mahan’和‘Pawnee’的光合能力及对光环境的适应能力均大于其它品种,但‘Mahan’对弱光的利用能力较弱;‘Mahan’暗呼吸速率最低,有利于光合产物的积累,‘Stuart’暗呼吸速率最高,消耗较多光合产物;对光合基本指标及其光响应特性的分析结果表明,气孔导度、蒸腾速率及瞬时羧化效率是影响净光合速率的重要因素,其中瞬时羧化效率对净光合速率有更直接显著的影响;相较于其它品种,‘Pawnee’抗旱能力较差,而‘Jinhua’抗旱能力较强;JIP-测定结果中,‘Stuart’质体醌容量(Sm)及电子传递活性较大,其各相荧光信号较弱,热耗散的能量较少,导致用于电子传递的能量较多,‘Kanza’的这些特性与‘Stuart’相反;品种间性能指数存在显著差异,‘Stuart’光合机构性能最优,‘Kanza’则较差;综合光合能力及光反应阶段的指标,发现5个薄壳山核桃品种中‘Stuart’光反应活性最大,但其光合能力最弱,可能和气孔限制因素、暗呼吸作用较强及光合机构形成的同化力较多地用于氮、硫同化等其它的代谢有关。