浅析海南芒果产业发展的现状和对策

芒果已成为海南支柱性的热点水果之一，成为振兴农村经济、脱贫致富的一项重要产业，但海南芒果产业在发展中存在的问题，束缚了海南芒果产业的可持续发展。现分析海南芒果产业发现的现状及存在的问题，并提出有关对策。     

国内外芒果科技发展现状与趋势

从遗传育种与栽培、病虫害防治、采后处理、深加工开发等方面，综述了近年来国内外芒果产业的科技发展现状，提出了芒果产业未来发展趋势。     

海南芒果产业可持续发展对策

从海南省芒果产业化发展的轨迹分析了海南省芒果的品种现状和果品优势,指出了芒果产业化发展中亟待解决的问题,并探索了一些解决问题的对策。     

正交优化芒果SRAP扩增体系及引物筛选

利用正交实验设计,对芒果SRAP-PCR反应的5因素(Mg2+、dNTPs、模板DNA、引物和Taq DNA聚合酶)4水平的扩增效果进行研究,确立适合芒果SRAP-PCR反应的最佳体系。总体积25μL的SRAP-PCR优化的最佳反应体系中含有:2.5μL 10×buffer、20 ng模板DNA、2.5 mmol/L Mg2+、0.2 mmol/L dNTPs、0.4μmo1/L Primer、Taq DNA聚合酶1.5 U。并运用该体系从153对引物组合中初步筛选出50对SRAP引物组合。建立的SRAP标记可为芒果遗传多样性、分子标记及辅助育种等提供研究基础。     

芒果蒂腐病菌对芒果采后乙烯释放和ACC含量的影响

测定芒果蒂腐病菌(Botryodiplodia theobromae)对芒果果实乙烯代谢的影响,结果表明:B.theobromae在芒果果肉培养基上不产生乙烯,但是B.theobromae代谢活动能诱导芒果果肉中产生大量的1-氨基环丙烷-1-羧酸(ACC),导致芒果快速释放乙烯,随着发病程度增加和贮藏期延长,乙烯释放速率快速增加。高浓度乙烯使芒果果肉快速软化,在25℃条件下,果实在发病后3～5 d就完全腐烂。     

浅谈永德芒果产业现状、问题与发展对策

简述云南永德芒果的栽培历史和产业现状,分析了目前芒果产业发展中存在的问题,提出促进产业发展的对策。     

蓟马复合种在芒果植株上的空间分布和理论抽样

为弄清蓟马在芒果植株上的空间分布格局,确定芒果蓟马监测及防控的抽样技术和方法,分别于芒果嫩梢期和扬花期,调查芒果植株不同冠层蓟马虫数。结果表明：不同地区芒果园蓟马的为害程度差异较大。芒果植株不同冠层均有蓟马分布为害,芒果花期取中、下层花穗,嫩梢期取中、上层叶片能较准确反应出植株的受害情况。芒果蓟马的分布型受种群密度的影响,密度低时为均匀分布,密度高时为聚集分布;聚集程度随密度升高而增大,个体间相互吸引。利用聚集均数分析聚集原因,发现芒果蓟马的聚集主要是由蓟马自身的习性和环境共同作用引起的。应用Iwao理论抽样原理,建立了芒果扬花期及嫩梢期的抽样模型：N =（8.8543/m +0.2098）t ²/D ²和N = (1.8462/m +0.1513)t ²/D ²。     

芒果产量与气象条件关系初探

芒果原产于印度,我国的广东、福建、台湾和四川等省均有大面积栽培,芒果肉质香甜、营养丰富、药用价值高,既可鲜食又可制成蜜饯、罐头、果干、果酱、果醋和果酒等,是名贵的热带水果.进一步搞好芒果生产,对发展农村经济有着十分重要的意义.多年来,芒果生产普遍存在着开花不结果、产量不稳定的问题,严重影响了芒果生产的发展.为了探讨芒果生产中影响产量的     

第二届厄瓜多尔国际芒果大会成功召开

2008年8月26～27日,由中国热带农业科学院主办、攀枝花市农林科学院承办的“农业部948项目晚熟芒果现场展示暨产业交流会”在四川省攀枝花市成功举办。中国热带农业科学院、海南大学、云南省农科院、广西亚热带作物研究所、福建省农科院、四川省农科院、攀枝花市农林科学院的专家、学者和攀枝花市芒果企业代表出席了会议,并就“948”项目晚熟芒果实施进展和计划进行了现场交流。参会代表就芒果产业发展问题作了专题报告,同时对攀枝花市混撒拉芒果基地和金河芒果基地进行了现场考察,并对生产中存在的问题进行了现场指导。     

干热河谷退化山地芒果园间种和翻压柱花草的效应研究

试验设计3个处理,第一个处理是在芒果(Mangifera indica Lour.)行间种植热研5号柱花草(Stylosanthes guianensis cv.Reyan No.5),观测芒果单作样地与芒果-柱花草间种样地土壤全氮、有机质和有机碳含量;第二个处理是在芒果-柱花草间种样地,在芒果树冠滴水线内翻压热研5号柱花草,观测芒果树下翻压与未翻压柱花草土壤营养成分、芒果生长量和产量及柱花草的鲜草产量,其主要目的是探讨果园间种柱花草的技术以及对土壤肥力与果树产量的影响;第三个处理是在芒果-柱花草间种样地,在芒果树冠滴水线内翻压农家肥,观测芒果树下翻压与未翻压农家肥芒果生长量和产量。试验结果表明：(1)芒果行间种植柱花草,间种样地土壤肥力得到改善,土壤全氮、有机质和有机碳增幅均高于芒果单作样地;(2)芒果树下翻压柱花草后土壤全氮、有机质和有机碳、芒果株高、冠幅、地径和产量均高于未翻压芒果株;(3)芒果树下翻压柱花草和农家肥处理的芒果株高、冠幅、地径和产量均高于未翻压芒果株;(4)试验为区域林果园间种牧草提供技术支撑和理论依据。     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

The Trichoderma koningii aggregate species

The morphological concept of Trichoderma koningii is found to include several species that differ from each other in details of phenotype (including conidium morphology, growth rate) and biogeography. Phylogenetic analysis utilizing partial sequences of the translation-elongation factor 1 alpha (tef1), as well as fragments of actin and calmodulin genes, indicate that phenotypic characters typical of T. koningii evolved independently in three well-separated main lineages. Combined molecular and phenotype data lead to the development of a taxonomy with the recognition of twelve taxonomic species and one variety within the three lineages. These lineages include: (1) T. koningii and T. ovalisporum and the new species T. caribbaeum var. caribbaeum, T. caribbaeum var. aequatoriale, T. dorotheae, T. dingleyae, T. intricatum, T. koningiopsis, T. petersenii and T. taiwanense; (2) the new species T. rogersonii and T. austrokoningii, and (3) the new anamorph T. stilbohypoxyli.Trichoderma koningii s. str. is an uncommon species restricted to Europe and eastern North America; T. caribbaeum var. aequatoriale, T. koningiopsis, and T. ovalisporum were isolated as endophytes of trunks of Theobroma species in tropical America, and T. ovalisporum from the woody liana Banisteropsis caapi in Ecuador; T. koningiopsis is common in tropical America but was isolated also from natural substrata in East Africa, Europe and Canada, and from ascospores in eastern North America, and as an endophyte in Theobroma species; T. stilbohypoxyli, originally described as a parasite of Stilbohypoxylon species in Puerto Rico, is found to be more common in the tropics, besides an endophytic isolate from Fagus in U.K. The additional new species are known almost exclusively from their teleomorphs. Isolates of T. ovalisporum and T. koningiopsis may have biological control potential. A morphophenetic key and a set of tools for molecular species identification were developed.Taxonomic novelties:Trichoderma austrokoningii/Hypocrea austrokoningii Samuels & Druzhinina sp.nov., T. caribbaeum var caribbaeum/H. caribbaea Samuels& Schroers sp.nov., T. caribbaeum var. aequatoriale Samuels & H.C. Evans var.nov., T. dingleyae/H. dingleyae Samuels & Dodd sp.nov., T. dorotheae/H. dorotheae Samuels & Dodd sp.nov., T. intricatum/H. intricata Samuels & Dodd sp.nov., T. koningiopsis/H. koningiopsis Samuels, C. Suarez& H.C. Evans sp.nov., T. petersenii/H. petersenii Samuels, Dodd & Schroers sp.nov., T. rogersonii/H. rogersonii Samuels sp.nov., T. stilbohypoxyli Samuels & Schroers sp.nov., T. taiwanense/H. taiwanensis Samuels & M.L. Wu sp.nov.     

La pourriture fongique des tubercules de pomme de terre en atmosphère contrôlée

Résumé Fusarium culmorum et, dans une moindre mesure,F. avenaceum, F. sambucinum, Colletotrichum coccodes etCylindrocarpon sp. ont été isolés de tubercules entreposés en atmosphère contr?lée (AC) et atteints de pourriture grave. Des expériences d'inoculation de tubercules avec 10 espèces ou variétés fongiques et conservation en AC à 8 et 10°C ont montré que: 1) les champignons non pathogènes en atmosphère normale (ex.:Cylindrocarpon sp.) le devenaient en AC, 2) ceux qui étaient faiblement pathogènes en atmosphère normale étaient nettement plus virulents en AC (ex.:F. culmorum), 3) les espèces ou variétés virulentes en conditions d'air normales (Fusarium sulphureum etPhoma exigua var.foveata) ne provoquaient pas de pourriture plus grave en AC et leur activité pouvait même être légérement freinée.

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Summary The extensive rotting of tubers which occurred during storage trials in controlled atmospheres has led to a mycological and pathological study of the rots. The most frequently isolated species wasFusarium culmorum althoughF. avenaceum, F. Sambucinum, Coletotrichum coccodes and aCylindrocarpon sp. were also present. Tubers of cvs Bintje and Ulla were inoculated with 19 isolates of 10 fungal species or varieties associated with rotting of stored tubers (Table 1). The tubers were incubated at 8 or 10°C in normal or controlled (2% O₂:1% CO₂, 2% O₂:6% CO₂, 2% O₂:12% CO₂, 6% O₂:6% CO₂) atmospheres and the extent of rotting was determined a month later (Tables 2 and 3 and Fig. 2). Species which were weakly virulent in a normal atmosphere (variousFusarium spp. andPhoma exigua var.exigua) were clearly more aggressive in the controlled atmosphere and this was especially evident in the case ofF. culmorum. Species ot pathogenic in a normal atmosphere under experimental conditions (Colletotrichum coccodes, Cylindrocarpon sp.,Phoma eupyrena) caused rotting in the controlled atmosphere. The two species which were virulent in a normal atmosphere (F. sulphureum andP. exigua var.foveata) were also virulent in the controlled atmosphere and in some cases the extent of rotting was even less. As a general rule, rotting caused by weakly virulent fungi was greater in both cultivars in the controlled than in a normal atmosphere.

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Zusammenfassung Eine starke F?ulnis von in Kontrotrollierter Atmosph?re gelagerten Kartoffelknollen veranlasste eine mykologische und pathologische Untersuchung. Der am h?ufigsten isolierte Pilz warFusarium culmorum. F. avenaceum, F. sambucinum, Colletotrichum coccodes undCylindrocarpon sp. wurden ebenfalls bestimmt. Neunzehn St?mme von 10 Pilzsorten oder-Arten welche bei Lagerf?ulnis vorkommen (Tab. 1) wurden auf Knollen der Sorten Bintje und Ulla inokuliert. Die Lagerung wurde bei 8 oder 10°C under Normalbedingungen oder kontrollierter Atmosph?re durchgeführt (2% O₂:1% CO₂, 2% O₂:6% CO₂, 2% O₂:12% CO₂, 6% O₂:6% CO₂). Der F?ulnisgrad (Abb. 1) wurde nach einem Monat bonitiert. Die Ergebnisse sind in den Tabellen 2 und 3 dargestellt und in der Abb. 2 illustriert. Unter in Normalbedingungen nur schwach virulente Arten (verschiedeneFusarien undPhoma exigua var. exigua) waren deutlich aktiver in kontrollierter Atmosph?re. Dies was besonders der Fall fürF. culmorum. Pilze, die im Versuch unter Normalbedingungen nicht pathogen waren (Colletotrichum coccodes, Cylindrocarpon sp., Phoma eupyrena), haben unter kontrollierter Atmosph?re Sch?den verursacht. Hingegen werden die beiden unter Normalbedingungen sehr pathogenen Arten (F. sulphureum undP., exigua var.foveata), durch kontrollierte Atmosph?re wenig beeinflusst. Es wurde sogar in einigen F?llen eine gewisse Verringerung des F?ulnisbefalls beobachtet. Ganz allgemein haben die getesteten kontrollierten Bedingungen die Entwicklung der Pilzf?ulnis an beiden Kartoffelsorten gef?rdert, speziell durch Pilzarten, welche unter Normal-bedingungen wenig Sch?den verursachen.

     

传统绿肥贵州山地景观化利用潜力评价

为了促进贵州观光农业与生态环境的协调发展,本研究对传统绿肥贵州山地景观化利用潜力进行评价。以贵州主要种植的传统绿肥光叶苕子（Vicia villosa var.）、紫云英（Astragalus sinicus L.）、箭筈豌豆（Vicia sativa L.）、肥田萝卜（Raphanus sativus L.）、山黧豆（Lathyrus cicera L.）、油葵（Oil-sunflower）、二月兰[Orychophragmus violaceus （L.） O.E. Schulz]为研究对象,分析其花朵时空分布特征、花朵视觉特性等景观效益,以及各绿肥作物的生长特性及养分效益。二月兰的开花时间最早,随后是肥田萝卜、山黧豆、紫云英,接着是光叶苕子、箭筈豌豆,而油葵是夏季绿肥,初花期为6月中旬,花穗期17~43 d,花期长短表现依次为二月兰>肥田萝卜>油葵>光叶苕子>紫云英>山黧豆>箭筈豌豆。花朵分布高度为油葵150~200 cm、肥田萝卜75~95 cm、二月兰与光叶苕子及箭筈豌豆25~50 cm、紫云英和山黧豆15~25 cm。单株花朵数光叶苕子最多。单朵花面积油葵最大。单株花面积光叶苕子最大。结合观光与保育目标,可利用绿肥作物打造2—3月间的二月兰蓝紫色花海,3—4月间的紫云英紫红色花海、肥田萝卜白色花海,4月间的光叶苕子紫色花海,6—7月间的油葵黄色花海,以丰富贵州观光休闲农业的观光色调,延长观光时间,实现观光品牌的多样化。     

Étude comparée des capacités infectieuses des différentes espèces ou variétés deFusarium responsables de la pourriture sèche des tubercules de pomme de terre

Résumé La capacité infectieuse de 5 espèces ou variétés deFusarium responsables de la pourriture des tubercules est étudiée.F. roseum var.sambucinum possède la capacité infectieuse la plus importante.F.r. var.arthrosporioides etF.r. var.culmorum sont, à l'inverse, caractérisés par une capacité infectieuse faible, ils ne produisent des pourritures qu'à des doses élevées de spores et sont rapidement limités par la cicatrisation. Enfin,F. solani var.coeruleum etF.r. var.graminearum possèdent un comportement intermédiaire. Le niveau de ‘virulence’ des 5Fusarium apprécié sur 9 cultivars, est identique mais leur niveau ‘d'agressivité’ varie; ils sont doués d'une agressivité non-spécifique (l'ensemble desFusarium provoque sur un cultivar déterminé, le même niveau de maladie) ou spécifique (une espèce ou variété deFusarium possède un comportement déterminé sur un cultivar qui ne correspond pas à celui des autresFusarium). Il est traité dans la discussion-conclusion de l'apport de ces résultats dans un programme de sélection vis-à-vis des Fusarioses.

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Summary The objective of this study is to confirm the infective potential of 5 species or varieties ofFusarium causing dry rot in potato tubers (F. roseum var.sambucinum (F.r. samb.), F. solani var.coeruleum (F.s. coer.), F. roseum var.arthrosporioides (F.r. arth.), F. roseum var.culmorum (F.r. culm.) andF. roseum var.graminearum (F.r. gram.)) in relation to different factors: inoculum level, wound type, time taken for wound healing, physiological age of tubers and cultivar. At low inoculum levels, certainFusarium can be highly aggressive, for exampleF.r. samb. and to a lesser extentF.s. coer. andF.r. gram., whereas others (F.r. arth. andF.r. culm.) can initiate a rot only when the inoculum level is high (Fig. 1 and Table 1). With respect to wounding (Tables 2 and 3),F.r. samb. causes extensive lesions regardless of wound type in contrast to the otherFusarium which do so only when the wounds are deeper than 2 mm. The reaction of the differentFusarium to wound healing is variable (Fig. 2). Some(F.r. culm. andF.r. arth.) are usually not affected whereas with others infection is arrested after a longer healing time: 8 days in the case ofF.s. coer. andF.r. samb. and longer withF.r. gram. Wound healing reaction can modify the relative ranking order of cultivars; a cultivar classified as resistant to aFusarium in the absence of healing can find itself grouped with the less resistant ones after wound healing probably because of a rate of healing lower than that of the other cultivars (Table 4). Behaviour of the different species and varieties ofFusarium is not affected differently by the physiological age of tubers; disease level is lower in young than in older tubers (Table 5). Moreover, cultivar reaction is more pronounced on young than on older tubers.

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Zusammenfassung Das Ziel dieser Studie ist es die Infektionskapazit?t von fünf Arten oder Sorten des für die Trockenf?ule der Kartoffelknollen verantwortlichenFusarium zu pr?zisieren (F. roseum var.sambucinum (F.r. samb.), F. solani var.coeruleum (F.s. coer.), F. roseum var.arthrosporioides (F.r. arth.), F. roseum var.culmorum (F.r. culm.) undF. roseum var.graminearum (F.r. gram.)) im Bezug auf diverse Faktoren: Inokulumdosis, Art der Verletzung, Wundheilungsdauer, physiologisches Alter der Knollen und Sorte. GewisseFusarium zeichen sich schon bei einer schwachen Dosis durch eine erh?hte Agressivit?t aus; dies ist der Fall fürF.r. samb. und mit verminderter St?rke, fürF.s. coer. undF.r. gram., die anderen hingegen (F.r. arth. undF.r. culm.) k?nnen nur bei gr?sseren Dosen von Impfstoff zu einer F?ule führen (Abb. 1 und Tab. 1). Was die Verletzungen betrifft (Tab. 2 und 3) provoziertF.r. samb. gr?sseren Schaden bei jeglicher Art von Verletzung im Gegensatz zu den anderenFusarium die nur bei einer Mindesttiefe der Verletzungen von 2 mm zu einer starken erkrankung fürhren. Im Bezug auf die Wundheilung sind unterschiedliche Reaktionen der verschiedenenFusarium zu beobachten (Darstellung 2); gewisse sind selten begrenzt (dies ist der Fall fürF.r. culm. undF.r. arth.), andere kommen nach einer l?ngeren Wundheilungszeit zum Stillstand: 8 Tage fürF.s. coer. undF.r. samb. oder noch l?nger fürF.r. gram. Die Vernarbungsreaktion kann das ungef?hre Sortenklassement ver?ndern; eine für ein Fusarium wenig empfindliche Sorte kann zu den Empfindlichsten geh?ren durch ihres Verhalten bei der Wundheilung, wenn ihre Vernarbungszeit l?nger dauert als die anderer Sorten (Tab. 4). Die verschiedenen Arten oder Sorten desFusarium reagieren auf gleiche Weise was das physiologische Alter der Knollen betrifft. Der Krankheitsbestand ist auf jüngeren Knollen schw?cher als auf ?lteren (Tab. 5). Weiter ist das Verhalten der verschiedenen Sorten deutlicher bei den jungen Knollen als bei alten.

     

Aktivitätsverteilung polysaccharid- und proteinabbauender Enzyme bei Kartoffelfäule-Erregern der GattungFusarium

Zusammenfassung Es wurde versucht, die unterschiedlichen Ausbreitungsmechanismen der beiden Lagerf?uleerregerFusarium coeruleum undFusarium sulphureum physiologisch-biochemisch teilweise aufzukl?ren Alle Isolate vonF. coeruleum undF. sulphureum vermochten Pectinmethylesterasen (PME). Polygalacturonasen (PG), Cellulasen und Proteasen zu bilden. Die Synthese der PME erfolgte bei beiden Pilzen konstitutiv und wurde durch Substratzusatz erheblich gesteigert.F. coeruleum bildete auch PG konstitutiv, nicht jedochF. sulphureum. Die Cellulase-Synthese erfolgte bei beiden Pilzen konstitutiv, die der Protease bevorzugt konstitutiv. Die Kulturdauer beeinflusste die Syntheserate der Enzyme unterschiedlich. PME und PG vonF. coeruleum zeigten im Gegensatz zuF. sulphureum keinen Aktivit?tsabfall innerhalb von 39 Tagen. Die Cellulase-Synthese des ersteren Pilzes stieg bis zum 18. Tag an, um dann langsam abzufallen, die des letzteren fiel nach starker Aktivit?t bei 3 Tagen nach 6 Tagen stark ab, um dann aber wieder über den gesamten Zeitraum stetig anzusteigen. Anders verhielt sich die Protease-Synthese, die beiF. coeruleum mit ca. 21 Tagen ihr Optimum erreichte.

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Summary In vivo,Fusarium coeruleum grows intercellularly andF. sulphureum intracellularly. The possible relationship between this and the activity of various enzymes has been investigated. All isolates ofF. coeruleum andF. sulphureum were able to produce pectinmethylesterases (PME), polygalacturonases (PG), cellulases and proteases. Both fungi synthesized PME constitutively, more being produced if substrate was added. PG was formed constitutively only byF. coeruleum. Cellulase synthesis was constitutive in both fungi and protease synthesis mainly constitutive (Fig. 2). The PME activity ofF. coeruleum was influenced by the N-source. inorganic N-compounds being more effective than organic in this respect. Peptone from casein was found suitable for PG activity. In contrast to the proteases, cellulase activity. In contrast to the proteases, cellulase activity was not greatly influenced by the N-source. The PME and PG ofF. coeruleum showed no loss of activity up to 39 days. The cellulase activity of this fungus increased up to 18 days and then declined. The cellulase activity ofF. sulphureum rose to a high level on the 3rd day. decreased after 6 days but increased again between the 9th and 39th day. Protease activity inF. coeruleum reached a maximum in 33 days and inF. sulphureum in 21 days (Table 2).

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Résumé II a été essayé d'éclaircir en partie par la voice de procédés physiologico-biochimiques le mécanisme différent de la propagation durant la conservation des deux agents de pourritureFusarium coeruleum etFusarium sulphureum. Touslesisolats deF.coeruleum etF. sulphureum ont été capables de développer des pectines-méthylestérases (PME), polygalacturonases (PG), cellulases et protéases. Pour les deux champignons, la synthèse de PME a été réalisée de manière constitutive et sensiblement activée par l'adjonction de substrats.F. coeruleum élabore aussi le PG de manière constitutive, contrairement à F. sulphureum. La synthèse de la cellulase fut constitutive pour les deux champignons, celle de la protéase fut de préférence constitutive (fig. 2). Le taux de la synthèse des enzymes varie pendant la duréc de la culture. Contrairement àF. sulphureum, les PME et PG deF. coeruleum n'ont pas diminué leur activité durant 39 jours. La synthèse de la cellulase deF. coeruleum s'est accrue jusqu'au 18e jour pour régresser ensuite lentement, celle deF. sulphureum, après une intense activité durant les 3 premiers jours, a fortement diminué pendant 6 jours puis a augmenté de fa?on continue jusqu'à la fin de la période. La synthèse de la protéase a évolué différemment; pourF. coeruleum, elle a atteint son optimum après 21 jours environ (tableau 2).

     

Cytoplasmic substitution inSolanum. II. Tuber characteristics of reciprocal backcross progeny

Summary Recurrent backcrosses (BC) were used to introduce nuclear factors ofS. tuberosum L. ssp.tuberosum into the cytoplasm of Andean potatoesS. tuberosum ssp.andigena (Juz. and Buk.) Hawkes andS. phureja Juz. and Buk. Each generation BC was produced in reciprocal directions to test the effect of cytoplasmic substitution on yield. This report analyses tuber number, tuber weight, and tuber length of BC₂ and BC₃ substitution into ssp.andigena cytoplasm and BC₂ and BC₂ substitutions intoS. phureja cytoplasm. Direction of cross had no consistent significant effect on yield components of ssp.andigena substitution lines. InS. phureja reciprocal progenies direction of cross was responsible for significant differences of some reciprocal sets. When there were significant differences the higher yield usually occurred when ssp.tuberosum was the pistillate parent, but in some progenies when ssp.tuberosum was the pistillate parent the yield was significantly lower than in the reciprocals. It is suggested that differences between reciprocals resulted from chromosomally encoded gene action, resulting from maternal and/or paternal effects, rather than cytoplasmic factors. Authorized for publication as paper No. 7494 in the Journal Series of The Pennsylvania Agriculture Experiment Station.     

Biochemical and morphological characterization of potato clones differing in their resistance to late blight

Summary Morphological and biochemical parameters that could be involved in resistance to late blight were studied in non-infected and in infected potato hybrids resulting from a cross betweenSolanum phureja, resistant toPhytophthora infestans, and a susceptibleSolanum tuberosum. Some morphological differences between resistant and susceptible hybrids, indicating a positive correlation between stem diameter and phloem thickness in the stem and resistance toP. infestans, were observed. The lignin content in the leaves of the resistant hybrid rose upon infection byP. infestans. In the leaves of the susceptible hybrid, a diminution of the lignin content could be observed upon infection byP. infestans. In the same context, peroxidasic activity raised upon infection byP. infestans in both resistant and susceptible hybrids. Further characterization of the hybrid clones based on the polymorphism of peroxidases was attempted using isoelectric focusing.     

Comparison of resistance toFusarium spp. of glasshouse-and field-grown tuber progenies of potato

Summary Field-grown tubers of 22 progenies ofSolanum tuberosum L. generated in a crossing programme involving seven parents differing in resistance toFusarium coeruleum Lib. ex Sacc. andF. sulphureum Schlect. (=F. sambucinum Fuckel, teleomorphGibberella pulicaris (Fr.) Sacc.) were wound-inoculated with a cornmeal + sand culture of each pathogen. Parental genotypes were also included. The mean lesion size of each progeny was compared in 2 years of tests, as well as with published data on glasshouse-grown tubers. ForF. coeruleum there was a high correlation between years as well as with the glasshouse data, but no such correlations were apparent withG. pulicaris. Furthermore, parental and GCA values, as well as progeny means and mid-parent scores, also correlated highly forF. coeruleum but not forG. pulicaris. Glasshouse-grown tubers of 11 wildSolanum spp. were also inoculated with both pathogens. Some resistance to one or other, or both, was apparent, particularly inS. chacoense.     

Variations in chemical characteristics and pulpability within jute plant (Chorcorus capsularis)

The differences in morphological and chemical characteristics and pulpability of core and bark fiber of jute at different position, top, middle and bottom were studied. The fiber length at the middle part of both bark and core was longer than the top and bottom part. With increasing height from bottom to top lignin content is decreased and α-cellulose content increased. The bark had higher α-cellulose and lower lignin than core. The bark produced nitrobenzene oxidation products with larger syringaldehyde/vanillin (S/V) ratios than the core. The yields of nitrobenzene oxidation products in bark were higher than core. The analysis of neutral sugars suggested that xylose is the predominant sugar of hemicellulose in both bark and core. The bark had higher glucose and lower xylose as compared to core. Under identical conditions of pulping, bark gave higher pulp yield and lower kappa number than core. The bark pulp showed better bleachability than core pulp. The higher tensile index in core pulp and higher tear index in bark pulp were observed.