Field resistance to late blight of four indian potato cultivars

Summary The nature and extent of field resistance to late blight, and the effect of plant age and inoculum level on resistance components and host attributes, were studied on the Indian potato cultivars Kufri Chandramukhi, Kufri Jyoti, Kufri Badshah and Kufri Sherpa. Latent period, infection efficiency, colonization rate and sporulation were found to operate in cvs Kufri Jyoti, and Kufri Badshah. Based on component analysis cv. Kufri Jyoti was similar to or sometimes more resistant than Kufri Badshah. No correlation was observed between any of the host attributes and resistance to late blight, except that the erect canopy of Kufri Badshah was associated with its slow blighting rate. At high inoculum, colonization rate and total sporulation were increased but infection efficiency was decreased.     

小麦品种里勃留拉和咸农4号持久抗条锈性特点分析

通过测定甘肃陇南持久抗条锈性小麦品种里勃留拉、咸农4号对小麦条锈病流行小种条中32号苗期、成株期的抗性,探讨和分析了它们持久抗条锈性的特点。结果表明,里勃留拉、咸农4号在苗期和成株期对条中32号均表现感病,在苗期抗性组分潜伏期、孢子堆密度、产孢强度、产孢期等指标上,里勃留拉与咸农4号和高感对照品种辉县红明显不同,咸农4号与辉县红基本相当。在成株期病害田间流行速率、病情指数、千粒重损失率等指标上,里勃留拉显著低于咸农4号和辉县红,咸农4号亦明显低于辉县红。里勃留拉和咸农4号的持久抗条锈性机理有所不同。     

高油玉米群体油分、蛋白质和淀粉含量近红外分析模型的构建

以BHO高油玉米F2∶3家系为材料,应用主成分空间和傅里叶变换近红外光谱分析技术,采用偏最小二乘回归法(PLS),建立了测定高油玉米子粒的油分、蛋白质和淀粉含量的近红外校正模型。预处理分别采用一阶导数 矢量归一化、一阶导数 多元散射校正及直线相减等方法,主成分维数分别为5、9、9。验证分析表明,所建立的油分、蛋白质和淀粉含量的校正模型的校正和预测效果最好,其校正决定系数(R2cal)分别为0.950、0.973、0.976,交叉验证决定系数(R2cv)和外部验证决定系数(R2val)在0.918～0.948,各项误差(RMSEE、RMSECV、RMSEP)在0.305%～0.721%。结果表明,所建立的高油玉米完整子粒品质性状三成分模型的准确度和精确度均较高,可以满足高油玉米群体大量样品无损品质分析的需要。     

Artificial Neural Network Modelling of Leaf Water Potential for Potatoes Using RGB Digital Images: A Greenhouse Study

Plant water status information of potato (Solanum tuberosum L. cv. Russet Burbank) is needed at the farm level for irrigation scheduling. This research investigated the feasibility of using a 5-megapixel digital camera to determine the leaf water potential (Ψ_L) of potato plants by capturing red, green, blue (RGB) digital images in the visible region of the electromagnetic spectrum. A greenhouse experiment was conducted in containerized cv. Russet Burbank potato plants subjected to five soil nitrate-nitrogen (N) levels and four soil water content levels. An artificial neural network (ANN) model, built with RGB images, RGB image transformations, RGB vegetation indices, and principal components analysis, found that for the validation data set, the measured Ψ_L and predicted Ψ_L results were from common populations. Other results showed: (1) a linear trend between soil nitrate-N levels and leaf reflectance in the G image band, (2) that the RG image bands were more suitable than the B image band for classifying leaf pigment from leaf shadow and leaf damage, (3) soil nitrate-N interacted with leaf greenness, affecting Ψ_L prediction, and (4) some image variables were more important than others in the ANN model. Although this greenhouse research shows promise, further field-based research is required to validate the selection of input neurons used and also validate the use of ANN modelling to determine Ψ_L at the plant canopy level with cv. Russet Burbank and other cultivars. In addition, an image acquisition method needs to be developed to obtain periodic representative sample coverage over a field.     

The physico-chemical properties of the seed and seed oil ofJatropha gossipifolia

The physico-chemical properties of the seed and seed oil ofJatropha gossipifolia were assessed by standard methods. The seed contains 35.8% crude oil of iodine value 107.25, 13.40% protein, 9.25% fibre, 30.32% carbohydrate and 6.0 g/kg saponins. The fatty acid composition of the seed oil was determined by GC-MS. Caprylic, myristic, palmitoleic, palmitic, oleic, stearic, linoleic, vernolic, arachidic, behenic and lignoceric acids were found.     

挥发性风味物质在碳水化合物中释放与保留的研究进展

风味的优劣逐渐成为食品能否得到消费者青睐的重要参考指标。碳水化合物作为食品主要营养成分之一,已被发现其对食品中挥发性风味化合物的保留与释放会产生显著的影响。本文综述了碳水化合物与风味化合物的作用方式,并分别从碳水化合物、风味化合物2种角度对挥发性风味物质在碳水化合物基质中释放与保留的影响因素进行了阐述,以期为风味物质在碳水化合物基质中的可控释放提供科学依据和参考。     

高温胁迫下糙米短期储藏气味指纹图谱变化规律的动态分析

【目的】探讨高温胁迫下短期储藏时间内糙米气味指纹图谱变化规律性,为糙米品质劣变的快速检测提供参考。【方法】以17.0%水分含量的新鲜糙米随机等分成6组进行储藏,采用顶空进样方式,分别结合气相色谱质谱联用技术（gas chromatography-mass spectrometry,GC-MS）和气相离子迁移谱技术（gas chromatography-ion mobility spectrometry,GC-IMS）,对高温储藏环境（40℃、相对湿度70%）中0、5、10、15、20和25 d的糙米挥发性化学成分及GC-IMS指纹图谱进行对比分析,并结合动态主成分和统计学方法进行数据分析。【结果】GC-MS定量分析表明,在新鲜糙米顶空气体成分中共检测出42种挥发性成分（GC-MS匹配度>85%）,主要由醛类、醇类、烃类组成,含量占比超过85%。高温短期储藏15 d后,正己醛含量从初始的（81.09±0.53）μg·kg^-1显著上升至（185.18±15.71）μg·kg^-1,储藏25 d时,又急剧下降至（12.89±0.72）μg·kg^-1（P<0.01）。部分物质如苯甲醇、1-辛烯-3-醇、苯乙烯等在储藏过程中被检出。结合GC-IMS方法,乙酸丙酯对应的气味挥发性色谱分离离子迁移信号随储藏时间延长而逐渐降低,可以作为糙米高温储藏期的重要标识物质。动态主成分降维处理后表明,基于GC-IMS气味指纹图谱可以区分不同储藏时间的糙米样品。与GC-MS相比,GC-IMS在糙米挥发性醇类、酮类等挥发性物质定性识别方面优势较为明显。【结论】GC-MS和GC-IMS技术结合气味指纹图谱的主成分分析可以对高温胁迫下短期储藏糙米的挥发特性进行有效的定性与定量分析,为高温环境下不同储藏阶段糙米样品的准确区分和糙米储藏新鲜度的判定提供技术参考。     

陕西秦巴烟区6年间烤烟主要化学成分含量的分布特征研究

通过检测和分析烟叶化学成分,探讨陕西秦巴烤烟品质状况,为选择优良品种和配套技术改善烟叶质量提供依据。于2012-2017年,从陕西秦巴烟区重点植烟县采集了197个烤烟样品,对烤烟烟碱、总氮、还原糖、总糖、钾、氯和淀粉等7个化学成分指标的含量分布特征进行了分析。结果表明,氯和淀粉的变异系数远高于其他成分。由偏度值可看出,秦巴烟叶中各化学成分频率分布基本上属于左偏型。不同年份之间的各指标均差异显著,其中2012年各指标明显高于其他年份。总氮、还原糖以及钾含量、氮碱比在不同品种之间差异显著,其中云烟97的钾含量为2.21%,还原糖含量为24.54%,均显著高于其他四个品种。总氮、还原糖、总糖、钾、两糖比在不同地区之间显著差异。不同部位烟碱、氮、总糖、钾含量差异显著。烟碱、总氮、还原糖、总糖、钾在烟叶中的浓度符合正态分布;氮碱比、糖碱比符合对数正态分布。烟碱、总氮、还原糖、钾在烤烟中符合国际型优质烟的概率为80.96%、91.27%、16.01%、75.84%。总体而言,陕西省秦巴烟区整体质量较好,尤其是烟碱和总氮的含量较为符合国际型优质烟标准,云烟97的化学成分协调性优于其他品种,根据不同烟区和不同部位烟叶的烟叶化学成分分布特征,采取技术措施进一步提高其协调性。     

丹参醇提物的抗菌作用研究

从丹参中提取醇溶性成分,采用微量稀释法探究丹参醇提物与8种抗生素联合对五种菌的体外抗菌活性。结果表明：丹参醇提物单独用药抑菌效果不佳,而与其他抗生素连用均展现不同抑菌效果;与头孢噻肟钠连用,使抑菌效果提高了6倍。浓度处于0.5 mg·mL^-1时控制效果最佳,肺炎克雷伯菌的菌丝生物量减少13倍左右。研究结果可为丹参醇提物的临床应用提供参考。     

广薯 87 鲜薯 和蒸薯挥发性风味成分分析

[目的]研究广薯87在蒸制前后挥发性风味成分的变化情况,为鲜食型甘薯风味物质改良提供参考.[方法]采用顶空固相微萃取(HS-SPME)和气相色谱-质谱联用仪(GC-MS)技术对广薯87鲜薯及蒸薯的挥发性风味成分进行比较和分析.[结果]广薯87鲜薯检测出71种挥发性物质,主要包括醛类(40.52％)、萜类(16.18％)、杂环类(15.17％)、醇类(11.59％)、酯类(7.94％)、芳烃类(4.49％)、酮类(1.62％)化合物等;蒸薯检测出69种挥发性物质,主要包括醛类(47.36％)、芳烃类(21.39％)、萜类(10.33％)、卤代烃类(7.07％)、醇类(3.24％)、酮类(2.64％)、酯类(2.61％)化合物等.其中,鲜薯及蒸薯中相对含量最高的挥发物均为苯乙醛,含量分别为16.78％、19.92％,但蒸煮前后相对含量差异不显著.对所检测出的挥发代谢物进行差异筛选,共筛选出47种差异明显的代谢产物.上调的代谢物有14种,下调的代谢物有33种,其中上调倍数最高的化合物为氯乙酸2-苯乙基酯,上调倍数为4.4;下调倍数最高的化合物为2-丙基-1H-咪唑,下调倍数高达13.49.[结论]结合相对含量及差异分析,广薯87蒸制后相对含量显著上升的主要挥发物成分为2,4-二叔丁基苯酚和氯乙酸2-苯乙基酯,是最有可能构成广薯87蒸薯特征风味的挥发物.