The drought response of landraces of wheat from the northern Negev Desert in Israel

Summary Diverse landraces of wheat, collected from the semi-arid (150 to 250 mm of total annual rainfall) Northern Negev desert in Israel were considered as a potential genetic resource of drought resistance for wheat breeding. These materials were therefore evaluated for their reponses to drought stress in agronomical and physiological terms. Up to 68 landraces, comprising of Triticum durum, T. aestivum, and T. compactum were tested in two field drought environments, in one favourable field environment, under post-anthesis chemical plant desiccation which revealed the capacity for grain filling from mobilized stem reserves, under a controlled drought stress in a rainout shelter and in the growth chamber under polyethylene glycol (PEG)-induced water stress. Biomass, grain yield and its components, harvest index, plant phenology, canopy temperatures, kernel weight loss by chemical plant desiccation, growth reduction by PEG-induced drought stress and osmotic adjustment were evaluated in the various experiments.Landraces varied significantly for all parameters of drought response as measured in the different experiments, which was in accordance to their documented large morphological diversity. Variation in grain yield among landraces under an increasing drought stress after tillering was largely affected by spike number per unit area. Kernel weight contributed very little to yield variation among landraces under stress, probably because these tall (average of 131 cm) landraces generally excelled in their capacity to support kernel growth by stem reserve mobilization under stress. Yield under stress was reduced with a longer growth duration of landraces only under early planting but not under late planting. Landraces were generally late flowering but they were still considered well adapted phenologically to their native region where they were always planted late.Landraces differed significantly in canopy temperature under drought stress. Canopy temperature under stress in the rainout shelter was negatively correlated across landraces with grain yield (r=0.67^**) and biomass (r=0.64^**) under stress. Canopy temperature under stress in the rainout shelter was also positively correlated across landraces (r=0.50^**) with canopy temperature in one stress field environment. Osmotic adjustment in PEG-stressed plants was negatively correlated (r=–0.60^**) with percent growth reduction by PEG-induced water stress. It was not correlated with yield under stress in any of the experiments. In terms of yield under stress, canopy temperatures and stem reserve utilization for grain filling, the most drought resistant landrace was the Juljuli population of T.durum.     

Genotypic and environmental variation in crop yield. A method of estimating the interdependence of the components of yield

Summary Because yield components do not behave as independent attributes the conclusions derived from simple yield analyses are of limited value in plant breeding programmes. By calculating a function W of the variances and covariances of the yield components, it is possible to estimate, on a scale from 0 to 1, the degree to which the variations in yield components were independent of one another in any given experiment. By this approach examples of almost complete compensation among the components (W = 0), of mutual independence of the components (W = 0.5), and of additivity of the components (W = 1.0) have been discovered in original data and in the literature. Reasons, and possible applications for these findings are discussed. Investigations into the sampling properties of W are reported in an appendix.     

冰温贮藏对山西不同产地玉露香梨挥发性有机物的影响

为了解冰温贮藏对不同产地玉露香梨挥发性有机物影响的差异性,采用气相离子迁移谱技术对山西省3个产地(隰县、原平、清徐)玉露香梨贮藏前后的挥发性有机物进行分析,以期为提升贮后果实风味品质提供数据参考。结果表明:通过气相离子迁移谱检测出玉露香梨采后主要挥发性有机物有酯类、醛类、醇类、酮类、酸类、呋喃类及其他未定性物质;其中酯类、醛类物质的相对含量占比达38.31%~39.10%。3个产地玉露香梨采后特征风味物质分别为:隰县玉露香梨为丙酸乙酯、丁酸乙酯、乙酸丙酯、(E)-2-己烯醛、2-甲基丙醛、壬醛等,原平玉露香梨为丙酸己酯、乙酸戊酯、丁酸己酯、己醛、3-戊酮、正己醇等,清徐玉露香梨为2-甲基丁酸甲酯、丁酸乙酯、乙醇、3-戊酮和异丁酸等。冰温贮藏后,3个产区玉露香梨果实的酯类物质含量有不同程度下降,醛类、醇类和酮类物质含量增加。其中隰县玉露香梨醛类物质相对含量较高,清徐玉露香梨酮类物质相对含量较高。根据风味物质的主成分分析,可将贮藏前后及3个产地玉露香梨进行有效区分。     

小麦产量构成因素的双列杂交分析

利用千粒重和每穗粒数有一定差异的7个冬小麦品种为亲本,按Griffing双列杂交法Ⅱ配制21个杂交组合,研究了小麦2个产量构成因素——千粒重和每穗粒数的遗传。结果表明,扬麦11千粒重和宁麦9号每穗粒数的一般配合力最好,且宁麦9号具有控制每穗粒数较多的显性基因。千粒重的遗传符合加性-显性-上位性模型。每穗粒数的遗传符合加...     

全有机营养液基质袋栽优质西瓜品种的筛选

【目的】研究全有机营养液基质袋栽条件下不同品种西瓜产量与品质的差异,筛选适宜全有机营养基质袋式栽培模式的西瓜品种。【方法】以14个西瓜品种(红小玉、苏梦907-099、苏梦RS66-57、小兰、苏梦907-126、苏梦907-032、早佳84-24、苏创5号、苏创4号、苏创907-145、苏创907-124、苏创907-144、苏创907-147、苏梦6号)为研究对象,其中苏梦6号同时用基质袋栽和土壤栽培方式,其他品种用基质袋栽方式,比较不同品种西瓜产量、果形指数、果皮厚度、单果质量等商品性状,中心可溶性固形物、边际可溶性固形物、可溶性总糖、还原糖、维生素C、可溶性蛋白含量等营养风味品质,以及挥发性物质含量、特征香气成分等芳香特性,通过顶空固相微萃取-气相色谱-质谱联用技术提取和分析不同品种西瓜挥发性物质成分,依据相对气味活度值筛选各品种西瓜关键香气成分,采用系统聚类法对西瓜品种进行分类,基于AHP-熵权法结合博弈论原理对不同西瓜品种品质进行综合评价。【结果】在全有机营养液基质袋式栽培条件下,苏创907-147产量最高,达54 125 kg/hm²;苏梦6号果皮最薄,仅4.18 mm;苏梦6号中心可溶性固形物、边际可溶性固形物及维生素C含量最高,分别为13.53%,11.37%,30.06 μg/g;从不同西瓜品种中共检测出114种挥发性物质,苏创907-145和苏创907-147中相对含量最高的分别是反,顺-2,6-壬二烯醛和十一醇,其余品种中均以顺-3-壬烯-1-醇相对含量最高;检测到的挥发性化合物包括醇类、醛类、烯类、酮类、烷类、呋喃类、酯类、其他类8大类,苏创907-145中醛类化合物相对含量最高,其余品种均以醇类化合物相对含量最高;苏梦RS66-57、小兰和苏创907-145挥发性物质成分较为特殊;苏创907-145中反,顺-2,6-壬二烯醛（黄瓜味）对总体风味贡献最高,早佳84-24、苏创907-144、苏创907-147、苏梦6号（土壤栽培）中顺,顺-3,6-壬二烯醛（瓜味、清香、稍有奶香）对总体风味的贡献最高,其余品种中贡献最高的为顺-3-壬烯-1-醇（清香、动物脂味）;苏创907-124香气最浓郁,芳香化合物总含量和关键香气成分总含量分别达到744.03和498.26 mg/kg,且香味独特。利用组合赋权法对不同品种进行综合打分,得分最高的为苏梦6号（基质袋栽方式）。【结论】供试14个西瓜品种中,苏梦6号最适宜进行全有机营养液基质袋式栽培。     

蔗渣堆沤过程的变化特征与“有效C／N比值”的应用研究

本研究测定不同堆沤时限蔗渣（新鲜和堆沤３，６，９及１２个月蔗渣）的理化性质，详细探讨蔗渣堆沤后的变化特征；并用分离的各蔗渣组分和多种纯无氮有机物来调节沙培系统的Ｃ／Ｎ比值，进行微生物夺取速效氮强度的模拟试验，查明了蔗渣中各组分和多种纯无氮有机物对微生物的有效性，确定蔗糖，淀粉，半纤维素和纤维素是微生物有效（速效）的碳源，而木质素是无产（迟效）的碳源。从而提出以“有效Ｃ／Ｎ比值”代替以往人们常用的“     

小麦品种产量与产量因素通径分析

通过对９４个不同品种小麦在渭北地区干旱条件下的试验数据,分类建立小麦产量与产量因素的回归关系,并做了通径分析。结果表明,在分类小麦的关系中,穗粒数对产量的总影响和直接影响都最大。     

福建青冈林不同恢复阶段植物生活型特征的研究

对福建青冈林各演替阶段的群落内植物成分特征的研究表明，各群落均以高位芽植物占优势，并有较大比例的藤本高位芽植物；各群落的生活型谱相似，说明它们相互之间的密切联系。小型叶植物、革质叶植物均占种数的一半以上，群落A、C、D、E内阴性植物的含量最大，而群落B内的阳性植物比例最高。     

豆蚜种群消长的主成分分析

运用主成分分析法(PCA),分析了室内繁蚜过程中豆蚜种群消长的主要因素。结果表明,影响豆蚜种群消长的主要因素有三类,分属三个主成分。第一主成分的特征根为3.34,是营养属性,对豆蚜种群消长的影响主要在繁蚜后期;第二主成分特征根为3.02,是生长率属性,主要在繁蚜中期起作用;第三主成分特征根为2.25,主要在繁蚜初期起作用。     

刺槐数量性状的主成分分析及分类

刺槐20个数量性状主成分分析研究结果表明:前5个主成分累计贡献率达85.93％,数量性状可分为4大类群,类群内部因子是正相关,类群之间因子是负相关或不相关。根据主成分因子负荷量及其主要指标组合,至少可看出5个因子对立木的作用。采用相关系数矩阵进行分类,优于用协方差矩阵进行分类。