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581.
Summary Thirteen cultivars were tested for presence ofPhoma exigua var.foveata in stems and green leaves. The frequency of segments yielding the pathogen increased with time during the growing season
and varied between cultivars from 13 to 36% and their distribution pattern was irregular. There were significant differences
between cultivars to this symptomless invasion of the green shoots. The value of such cultivar differences depends on the
interpretation of the importance of stem inoculum in carrying the disease to the next tuber generation.
Zusammenfassung Es wurden 13 Kartoffelsorten auf das Vorhandensein vonPhoma exigua var.foveata in Stengeln und grünen Bl?ttern untersucht. Pflanzknollen, die nach künstlicher Infektion faulten, wurden im Feld ausgepflanzt; nach 5, 12 und 17 Wochen wurden pro Sorte vier Stengel mit Bl?ttern nach dem Zufallsprinzip ausgew?hlt, wobei jeder Stengel eine Pflanze repr?sentierte. Die Stengel wurden gewaschen, getrocknet und in 5 cm-Segmente geteilt. Nach Oberfl?chensterilisation wurden die Segmente und die Blattschnitte in Petrischalen auf ein selektives Agarmedium gebracht, das zur F?rderung der Pyknidienentwicklung Paraquat enthielt.P. exigua var.foveata wurde auf Malzextraktagar bestimmt, der Thiophanatmethyl und Chloramphenicol enthielt. Die Sorten reagierten unterschiedlich auf die Infektion, wie an der Anzahl der Schnitte, die das Pathogen lieferten, zu ersehen ist. Die Nachweish?ufigkeit war am niedrigsten bei der ersten und am h?chsten bei der letzten Probenahme (Tab. 2). Die mittleren Prozentwerte varierten von 13% bis 36%, die Reihenfolge war zwischen den Jahren ?hnlich (Tab. 1). Das Verteilungsmuster der Schnitte, die das Pathogen lieferten, war unregelm?ssig; es wurde überall in Stengelschnitten und Bl?ttchen vom oberirdischen Trieb nachgewiesen und in nur wenigen F?llen auch in Stengelsegmenten unterhalb der Bodenoberfl?che (Tab. 3). Die Werte zeigen, dass die Anf?lligkeit der Sorten zur symptomlosen Invasion der grünen Triebe differiert. Inwieweit in dieser Phase des Lebenszyklus des Pilzes eine Resistenzauslese lohnend ist, h?ngt von der m?glichen Bedeutung des Stengelinokulums als Quelle für die Infektion der Knollennachkommenschaft ab. Es war mit dieser Untersuchung nicht beabsichtigt, Fragen, die sich auf die Ausbreitung des Pilzes beziehen, zu beantworten; ein besseres Verst?ndnis der Biologie dieses Krankheitserregers ist aber entscheidend zur rationalen Anwendung der Ergebnisse in der Pflanzenzüchtung.
Résumé La présence dePhoma exigua var.foveata dans les tiges et les feuilles vertes est étudiée sur treize variétés de pommes de terre. Des tubercules de semence pourris après contamination artificielle, sont plantés au champ. Après 5, 12 et 17 semaines, 4 tiges avec les feuilles de chaque variété sont prélevées au hasard, chaque tige représentant une plante. Les tiges sont lavées, séchées et coupées en segments de 5 cm. Après une stérilisation de surface les segments et des sections de folioles sont placés en boites de pétri sur un milieu sélectif à base d'agar contenant du paraquat afin de favoriser le développement des pycnides.Phoma exigua var.foveata est identifié sur malt agar contenant du thiophanate-méthyl et chloramphenicol. Les variétés répondent différemment à l'infection, comme le montre le nombre de sections hébergeant le pathogène. La fréquence de détection est la plus faible à la première date d'échantillonnage et la plus élevée à la dernière (tableau 2). Le pourcentage moyen varie entre 13 et 36%, le classement est similaire entre les années (tableau 1). La distribution du pathogène hébergé par les échantillons est irrégulière. Il est détecté sur des sections de tiges et des folioles au dessus du sol et dans quelques cas sur des segments de tiges en dessous de la surface du sol (tableau 3). Les données montrent que la sensibilité des variétés à l'infection des parties aériennes est variable. L'intérêt d'une sélection à la résistance pour cette phase du cycle du champignon dépend de l'importance potentielle de l'inoculum sur tige en temps que source de contamination des tubercules-fils. Cette étude n'a pas pour but d'expliquer la dissémination du champignon, mais une meilleure connaissance de la biologie du pathogène est fondamentale pour une application rationnelle des résultats de la multiplication variétale.相似文献
582.
583.
The aim of this study was to understand the off-axis tensile properties of the developed two dimensional multistitched multilayer E-glass/polyester woven nano composites. It was found that the specific off-axis tensile strength of unstitched structure was higher than that of the machine stitched structure due to stitching caused filament breakages. But it was slightly lower than that of the machine stitched/nano structure. In addition, the specific off-axis tensile strength of machine stitched/nano composite structure was slightly higher than that of the machine stitched structure. When the nano silica material in the unstitched E-glass/polyester composite structure increased, the off-axis specific tensile strength and the modulus of the unstitched/nano structures increased whereas, the off-axis specific tensile strain of the unstitched/nano structures decreased. The damaged areas of the unstitched/nano structures increased, when the nano silica material in the unstitched E-glass/polyester woven composite structures increased. The failures under the off-axis tensile load of the stitched or stitched/nano structures were confined at narrow area due to the multistitching. On the other hand, it was observed that the off-axis failure of unstitched/nano or stitched/nano woven E-glass/polyester composite structures showed more brittle behavior. 相似文献
584.
Seeds of Butea monosperma administered as crude powder (CP) at doses of 1, 2 and 3 g/kg to sheep naturally infected with mixed species of gastrointestinal nematodes exhibited a dose and a time-dependent anthelmintic effect. The maximum reduction of 78.4% in eggs per gram of feces (EPG) was recorded on day 10 after treatment with 3 g/kg. Levamisole (7.5 mg/kg), a standard anthelmintic agent, exhibited 99.1% reduction in EPG. 相似文献
585.
The importance of demographic niches to tree diversity 总被引:1,自引:0,他引:1
Condit R Ashton P Bunyavejchewin S Dattaraja HS Davies S Esufali S Ewango C Foster R Gunatilleke IA Gunatilleke CV Hall P Harms KE Hart T Hernandez C Hubbell S Itoh A Kiratiprayoon S Lafrankie J de Lao SL Makana JR Noor MN Kassim AR Russo S Sukumar R Samper C Suresh HS Tan S Thomas S Valencia R Vallejo M Villa G Zillio T 《Science (New York, N.Y.)》2006,313(5783):98-101
Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site. This allowed us to test the prediction that demographic differences facilitate species richness, as suggested by the theory that a tradeoff between high growth and high survival allows species to coexist. Contrary to the prediction, the most diverse forests had the least demographic variation. Although demographic differences may foster coexistence, they do not explain any of the 16-fold variation in tree species richness observed across the tropics. 相似文献
586.
Nazir Muhammad Mudasser Oneeb Muhammad Ayaz Muhammad Mazhar Bibi Fehmeeda Ahmad Atif Nisar Waheed Abdul Sajid Muhammad Afzal Sultan Muhammad Tauseef Yasin Ghulam Lindsay David S. 《Tropical animal health and production》2017,49(5):1081-1084
Tropical Animal Health and Production - Infection with the Apicomplexan parasite Neospora caninum occurs in domestic and wild animals worldwide. This parasite causes significant economic losses in... 相似文献
587.
588.
Abdul Qayyum Abdul Razzaq Yamin Bibi Sami Ullah Khan Kashif Sarfraz Abbasi 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(4):283-290
Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of ?8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes. 相似文献
589.
Abdul Khaliq M. Kaleem Abbasi Imtiaz Hussain 《Archives of Agronomy and Soil Science》2018,64(5):640-653
This study provided an insight on improving soil-plant micronutrients availability in response to poultry manure (PM), wheat milling residues (WMR) and urea N (UN) and their integration in wheat–soybean cropping system. The treatments were: control; poultry manure full, PM100; wheat milling residues full, WMR100; urea N full, UN100; PM half and WMR half, PM50+WMR50; UN50+PM50; UN50+WMR50; UN50+PM25+WMR25. All amendments were added at the rate or equivalent to 100 kg total N ha–1. Results indicated that the integrated treatments increased Cu, Fe, Mn and Zn uptake of wheat by 35.7–103%, 48.4–111.1%, 85.2–267.0% and 33.8–128.2%, respectively over control. In soybean the corresponding increase in micronutrient uptake (Cu, Fe, Mn and Zn) was 18.3–60.3%, 27.5–87.4%, 14.1–54.6% and 13.2–58.0% in integrated treatments. The post-harvest soil analysis indicated 2 to 3-fold increase in micronutrient content with highest values in PM100 i.e., 2.66 mg kg?1 for Cu, 14.41 mg kg?1 for Fe, 18.58 mg kg?1 for Mn and 2.44 mg kg?1 for Zn, respectively. The results showed that the PM either alone or in integrated with WMR and UN can be an effective management strategy for improving micronutrient content of soil–plant. 相似文献
590.
Sherwin Chan Kit Lee Abu Bakar Rosenani Che Fauziah Ishak Azni Idris Khairuddin Abdul Rahim Andreas Meyer-Aurich 《Archives of Agronomy and Soil Science》2017,63(12):1711-1724
Converting oil palm empty fruit bunches into biochar is an alternative waste management method and has strong potential to improve N fertiliser use efficiency in agriculture. The aim of this study was to determine the effectiveness of oil palm empty fruit bunch biochar (EFBB) in improving recovery of 15N-labelled nitrogen fertiliser by maize (Zea mays L.) and leaching of mineral N and K. An experiment was conducted in a mini-lysimeter system with randomised complete block design layout and six replications under controlled environment in a rain shelter. Each mini-lysimeter was filled with 20 kg of sandy loam soil before adding EFBB (0, 5, 10 and 20 Mg ha?1). The N source used was (15NH4)2SO4 at 80 kg N ha?1 (2 at% 15N excess). Maize was irrigated to induce leaching every 4 days. Maize plant and soils were sampled 58 days after sowing (tasselling stage). Application of EFBB significantly reduced cumulative leachate volume and mineral N leaching. Soils applied with EFBB significantly improved 15N fertiliser recovery in maize and dry matter weight. This study shows that EFBB has the potential to be applied on highly weathered acidic soil as an amendment to improve fertiliser efficiency and crop growth. 相似文献