不同调制工艺对烘烤过程中烟叶致香物质的影响

为研究烟叶致香物质在烘烤过程中的变化,提高致香物质含量,以‘K326’为材料,研究了4种调制工艺（A香气前体物质中度转化、致香物质中度积累型,B香气前体物质中度转化、致香物质高度积累型,C香气前体物质深度转化、致香物质中度积累型,D香气前体物质深度转化、致香物质高度积累型）对烘烤过程中烟叶致香物质含量的影响。结果表明,下部和中部烟叶致香物质含量最高值出现在烘烤过程的后期阶段,上部烟叶致香物质含量最高值出现在烘烤的前期阶段。下部烟叶采用D调制工艺可以减少致香物质的损失,采用A调制工艺烘烤结束时致香物质含量最高;中部烟叶采用B调制工艺可以减少致香物质的损失,且烘烤结束时致香物质含量最高;上部烟叶采用A调制工艺可以减少致香物质的损失,采用C调制工艺烘烤结束时致香物质含量最高。     

采收时间对烤烟烟叶中性致香物质和感官质量的影响

采用烤箱对成熟度一致的烤烟烟叶进行烘烤,通过对不同采收时间的烤烟烟叶中性致香物质含量和感官质量的分析,对烤烟烟叶成熟采收的外观标准进行量化,以期寻找能够提高香气质、量的烤烟成熟外观标准,为烤烟生产提供理论支撑。结果表明：各部位烟叶外观标准为：下部叶在移栽后60-65d,叶龄在45-50d,叶尖微黄,主脉1/3-1/2、支脉3-5对变白,叶片下垂程度达到1.19-1.20,茎叶夹角70°-75°;中部叶推迟到移栽后95d,叶龄达在65d,叶面黄中带青,主脉2/3以上、支脉8-9对变白,叶片下垂达到1.30,茎叶夹角70°,有成熟斑和焦尖现象;上部叶在115d后采收的烟叶,叶龄在75d以上,叶面几乎全黄,主支脉全白,叶面下垂程度达到1.54以上,茎叶夹角达到75°,有成熟斑和焦尖现象。达到此成熟标准时采收,烤后烟叶中性致香物质含量较高,感官质量评价得分较高,香气质较好,香气量较足。     

白肋烟不同叶位叶片中性香气成分和生物碱含量的变化

以白肋烟达白1号非烟碱转化株为材料,在2种留叶数（每株18,24片）条件下研究了不同叶位叶片晾制后生物碱和中性香气成分含量的变化。结果表明,烟碱和仲胺类生物碱含量均随叶位增高而增加,少留叶烟株不同部位生物碱含量均高于多留叶烟株,且上下部位间变幅相对较小。中性香气成分含量呈现不同变化趋势,少留叶烟株各叶位巨豆三烯酮含量高于多留叶烟株,且表现为随叶位升高而增加,多留叶烟株巨豆三烯酮含量以中部叶最高,上部叶含量呈显著降低。其他质体色素降解产物,除β-大马酮含量以中部及偏下部位烟叶较高外,一般表现为随叶位升高而增加。西柏烷类降解产物茄酮含量以中部叶含量较高,多留叶烟株各部位叶片,特别是上部叶茄酮含量高于少留叶烟株。苯丙氨酸降解产物苯乙醛和苯乙醇含量随叶位升高而显著增加。     

云南与津巴布韦烤烟致香物质含量差异研究

【研究目的】为明确云南与津巴布韦烤烟在致香物质方面的差距，指导云南部分替代进口烤烟的研究和生产，提高烟叶质量，特进行此项试验。【方法】采用比色法测定了烟叶多酚总量，索式提取法测定石油醚提取物，硫酸甲酯、三氯甲烷萃取法测定多元酸和高级脂肪酸，水蒸汽-二氯甲烷同时蒸馏萃取、GC/MS-内标定量检测挥发性香气物质；并分类分析比较了云南与津巴布韦烤烟的多酚总量、石油醚提取物、多元酸、高级脂肪酸及挥发性香气物质等烟草致香物质含量的差异。【结果】结果表明云南烤烟各部位烟叶的石油醚提取物、芳香氨基酸降解的香气物质超过津巴布韦烤烟，多酚、高级脂肪酸则低于津巴布韦烤烟；上部烟叶的西柏烷类香气物质高于津巴布韦烤烟，多元酸、类胡萝卜素降解的香气物质、梅拉德反应的香气物质则低于津巴布韦烤烟；中部和下部烟叶的多元酸、类胡萝卜素降解的香气物质、梅拉德反应的香气物质高于津巴布韦烤烟，而西柏烷类香气物质则低于津巴布韦烤烟。云南与津巴布韦烤烟在致香物质方面的差距，主要表现在上部烟叶的柠檬酸、油酸、巨豆三烯酮、金合欢基丙酮、β-二氢大马酮、二氢猕猴桃内酯、糠醇、糠醛等致香物质含量低于津巴布韦烟叶。【结论】云南与津巴布韦烤烟的致香物质差异比较明显，上部烟叶致香物质含量明显不如津巴布韦。     

氮用量对烟叶质体色素及中性香气基础物质的影响

质体色素及中性香气基础物质是影响烤烟香气质量的重要因素。为了采取合理的氮肥调控措施提高烤烟香气质量,研究了不同氮用量条件下8306和K326两个烤烟基因型叶片质体色素及中性香气基础物质的变化,结果表明:烟草鲜烟叶叶绿素和类胡萝卜素含量随氮用量增加而增加,随烟草生育期推进而减少,与K326相比,高香气基因型8306叶片叶绿素含量较低,而类胡萝卜素含量较高。不同基因型烤后烟叶中性香气基础物质总量,随氮用量增加8306的含量升高,K326的含量降低,在基因型间则表现为8306的含量高于K326的含量。8306和K326两个烤烟基因型,成熟期鲜烟叶类胡萝卜素含量与烤后烟类胡萝卜素降解产物呈极显著正相关关系。     

有机初烤烟叶中性致香物质特征分析

采用同时蒸馏萃取法、内标法和气相色谱—质谱联用法(GC/MS)技术,以常规烟叶作对照,研究了有机初烤烟叶中性致香物质组分及其含量.结果表明:有机烟叶和常规烟叶中性致香物质的种类基本相同,但含量却有较大差异,且部位间也有明显的差异,在所测定的28种主要中性致香物质中,总量均表现为上部叶＞下部叶＞中部叶;有机烟叶除上部叶中苯丙氨酸类致香物质略低于常规烟叶外,类胡萝卜素类、类西柏烷类、棕色化产物类致香物质和中性致香物质总量在3个部位均高于有机烟叶,其中,以中部叶提高幅度最大.     

湖南与河南烤烟烟叶中挥发性致香物质的对比分析

[目的]将湖南与河南两省烤烟中的中性香气成分的含量进行对比,以明确两省烤烟在致香物质方面的差异,从而为探讨两省卷烟风格差异的形成原因提供一定的依据。[方法] 采用美国HP5890Ⅱ-5972气质联用仪定性、内标定量法。[结果]结果表明,在所测出的中性致香成分中,湖南B2F烤烟质体色素类,美拉德反应产物等香气物质总量均比河南烤烟高,而湖南C3F烤烟中的新植二烯,美拉德反应产物和苯丙氨酸类香气物质总量却低于河南同等级烤烟。[结论]湖南与河南烤烟的中性致香物质差异比较明显,河南烟叶致香物质总量明显低于湖南。     

南雄烟区主栽烤烟品种成熟期丙二醛含量变化规律研究

通过对南雄烟区不同烤烟品种成熟过程中活体、离体烟叶丙二醛含量及其变化规律分析,揭示不同烤烟品种烟叶的成熟度与丙二醛含量及其变化的规律相关性差异。结果表明:(1)大田状态下,上部烟叶,‘K326’丙二醛含量随时间呈"S"型变化,‘粤烟97’、‘粤烟98’丙二醛含量随时间呈类指数型变化,采收时MDA含量分别为21.35、18.75、20.59μmol/g;中部叶,3个烤烟品种均呈类指数型变化,采收时烟叶MDA含量为19.74、12.55、12.98μmol/g。(2)离体状态下,上部烟叶,‘K326’丙二醛含量随时间呈类指数型变化,‘粤烟97’和‘粤烟98’呈"S"型变化;中部烟叶,3个烤烟品种均呈"S"型变化。(3)离体烟叶MDA含量在短时间内达到大田状态下成熟采收时的含量水平,而离体后上、中部烟叶MDA含量均呈现"S"型变化趋势,当达到采收值时正好处于离体烟叶"S"型变化趋势的拐点,即离体烟叶MDA含量变化到达拐点之前与大田状态下MDA含量的变化趋势一致。研究表明不同烤烟品种在烤烟成熟过程中丙二醛含量及其变化规律可以指示其成熟度。     

烟草对氮吸收利用的研究

本文采用＾１５Ｎ示踪研究烟草对氮的吸收分布，结果表明烟草的积累量中部叶片＞上部叶片＞下部叶片，而全氮、蛋白态氮、烟碱氮的相对含量均呈上部叶＞中部吉＞下部叶的规律；无论全氮含量还是含氮化合物，它们与其中肥料氮组成比例间的关系都有一致的表现。     

烤烟品种‘K326’不同部位适宜成熟度采收研究

采用田间试验研究了烤烟‘K326’ 品种不同部位成熟采收的标准。结果表明,烤烟品种‘K326’下部叶在5成熟时采收表现较好,香气量足,浓度高,杂气和刺激性均较小;中部叶8成采收,烘烤质量最好,颜色鲜亮、油分多,单叶重较重;上部叶在9成黄时采收的表现最好,香气量足,杂气和刺激性均低。试验结果对烤烟品种‘K326’的种植及提高其产质量具有重要意义。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.