Vegetation Period (vegetation + period)

Distribution by Scientific Domains


Selected Abstracts


Structure and diversity of Gram-negative sulfate-reducing bacteria on rice roots

FEMS MICROBIOLOGY ECOLOGY, Issue 2-3 2001
Daniel Scheid
Abstract Specific PCR assays were used to amplify the 16S rRNA genes of the Desulfobacteriaceae and the Desulfovibrionaceae from extracted environmental DNA from rice roots. 16S rDNA-based community patterns of the Desulfobacteriaceae were generated via terminal restriction fragment length polymorphism analysis from rice roots and compared with bulk soil. The molecular fingerprints showed no significant difference between rice roots and bulk soil, but changes during the vegetation period. 16S rDNA clone libraries and sequencing showed that the predominant terminal restriction fragments represented distinct phylogenetic groups. The 16S rDNA clone sequences of the Desulfobacteriaceae fell in the phylogenetic radiation of Desulfonema and Desulfosarcina or grouped within the Desulforhabdus,Syntrophobacter assemblage. Three of the latter sequences were closely affiliated with the MPN isolate EZ-2C2 from rice roots. All Desulfovibrionaceae 16S rDNA clone sequences, with one exception, were affiliated with the MPN isolate F1-7b from rice roots. The clustering of the clone sequences and the close phylogenetic affiliation with isolates from MPN enrichments from the same habitat in two cases indicated that these sequence clusters may represent predominant Gram-negative sulfate reducers on rice roots. Quantification of the bacterial abundances was accomplished by rRNA dot blot hybridization. In total the Gram-negative sulfate reducers accounted for approximately 2,3% of the total rRNA content. The relative rRNA abundance of the Desulfobacteriaceae was, at 1.4%, higher than that of the Desulfovibrionaceae (0.5%). [source]


Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash in northern Sweden

FOREST PATHOLOGY, Issue 6 2006
J. Witzell
Summary Survival and vitality of Gremmeniella abietina on Pinus sylvestris slash was studied in northern Sweden during 2003 and 2004. Once a month between September 2003 and April 2004, two to three trees were cut down and debranched. Shoots with pycnidia were sampled at the felling date and then at every consecutive month. The percentage of germinated conidia from each shoot was calculated after 24, 48 and 72 h incubation. The vitality of G. abietina pycnidia in the slash remained high the whole period. Intact pycnidia were found on slash several months after the time of conidial sporulation, which indicates that new pycnidia may be produced on dead pine branches. Sampling of shoots from slash on 13- to 18-month-old clear-cuts showed conidial germination capacity as high as in pycnidia collected in fresh slash. Due to survival of G. abietina in slash it is recommended to postpone planting of P. sylvestris seedlings in northern boreal areas to the third vegetation period after sanitary clear-cuts. Résumé La survie et la vitalité de Gremmeniella abietina dans des rémanents de Pinus sylvestris ont étéétudiées dans le nord de la Suède pendant les années 2003 et 2004. Une fois par mois entre septembre 2003 et avril 2004, 2 ou 3 arbres ont été abattus et ébranchés. Des pousses avec pycnides ont étééchantillonnées à la date d'abattage et les mois suivants. Le pourcentage de conidies germées a été calculé pour chaque pousse après 24, 48 et 72 heures d'incubation. La vitalité des pycnides de G. abietina dans les rémanents est restée élevée tout au long de la période. Des pycnides intactes ont été trouvées dans les rémanents plusieurs mois après la période de sporulation conidienne, ce qui suggère que de nouvelles pycnides peuvent être produites sur des branches mortes de pin. Des échantillonnages de pousses dans des rémanents de coupes rases réalisées 13,18 mois plus tôt ont montré une capacité de germination des conidies aussi élevée que dans les pycnides collectées dans des rémanents fraîchement coupés. Du fait de la survie de G. abietina dans les rémanents, il est conseillé de reporter la plantation des semis de P. sylvestris dans les zones septentrionales boréales à la troisième saison de végétation après les coupes sanitaires. Zusammenfassung Das Überleben und die Vitalität von Gremmeniella abietina auf Schlagabraum von Pinus sylvestris wurde in den Jahren 2003 und 2004 untersucht. Zwischen September 2003 und April 2004 wurden in jedem Monat einmal 2,3 Bäume gefällt und entastet. Zum Zeitpunkt des Fällens und in jedem folgenden Monat wurden Triebe mit Pyknidien gesammelt. Von jedem Trieb wurde die Keimrate der Konidien nach 24, 48 und 72 Stunden Inkubation bestimmt. Während der gesamten Beobachtungsdauer blieb die Vitalität der Pyknidien im Schlagabraum hoch. Mehrere Monate nach der Sporulation wurden intakte Pyknidien gefunden, ein Hinweis darauf, dass möglicherweise neue Pyknidien auf den toten Kiefernzweigen gebildet wurden. Auf dem Schlagabraum von 13,18 Monate alten Kahlschlägen war die Keimfähigkeit der Konidien ähnlich hoch wie bei Pyknidien von frischem Schlagabraum. Aufgrund des langen Überlebens von G. abietina in Schlagabraum wird für die nördlichen borealen Gebiete empfohlen, nach phytosanitären Kahlschlägen P. sylvestris -Sämlinge erst in der dritten Vegetationsperiode zu pflanzen. [source]


Colonization of beech leaves by two endophytic fungi in northern Japan

FOREST PATHOLOGY, Issue 2 2000
N. Sahashi
Summary Leaves of Japanese beech (Fagus crenata) were collected monthly during the vegetation period at five sites in the Tohoku district in Japan to isolate endophytic fungi. Leaves were also collected only once at two additional sites. Two endophytic fungi were dominant, a Discula species and a sterile mycelium. This result strongly suggests that these two fungi are generally associated with leaves of the Japanese beech at different sites. At most sites the isolation frequency of Discula sp. was greatest in June and gradually decreased from July to October whereas the isolation frequency of the sterile mycelium increased during the vegetation period and remained at a high isolation frequency in October. Spores of Discula sp. were released for a very short time in late May, just after the disappearance of the snow cover on the forest floor. These spores may be important for the infection of newly sprouting leaves. [source]


Organic fertilizers derived from plant materials Part II: Turnover in field trials

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006
Torsten Müller
Abstract Our aim was to investigate two different organic fertilizers derived from plant materials (OFDP) with respect to their nitrogen (N) and carbon (C) turnover in field trials planted with small radish (Raphanus sativus L. var. sativus) and white cabbage (Brassica oleracea L. convar. capitata var. alba) or fallow. The two fertilizers investigated were coarse seed meal of yellow lupin (Lupinus luteus L.) and coarse meal of castor cake (Ricinus communis L.). Under cool spring conditions, the soil turnover of yellow lupin,seed meal was slightly enhanced compared to castor-cake meal. During the vegetation period of the vegetables, N added with both fertilizers was metabolized more or less completely by soil microorganisms. Due to similar efficiencies of the fertilizers tested, no significant difference could be found in the N uptake of plants. From this point of view, yellow lupin,seed meal, which can be produced by farmers themselves, has the potential to replace the widely used castor-cake meal. Considerable amounts of N may remain in the field after fertilization with OFDPs either as mineral N or as easily mineralizable organic N. This N should be utilized immediately by a succeeding crop to avoid leaching losses. [source]


Effect of sowing date and straw mulch on virus incidence and aphid infestation in organically grown faba beans (Vicia faba)

ANNALS OF APPLIED BIOLOGY, Issue 2 2009
H. Saucke
Abstract The effect of sowing date on aphid infestation and the incidence of aphid-transmitted viruses were investigated in organically managed, small-scale field experiments with two faba bean cultivars over 3 years (2002,04). As an additional factor, straw mulch was applied in 2 of the 3 years shortly before the start of vector activity in May. Virus incidence was determined using enzyme-linked immunosorbent assay and immunoelectron microscopy. Aphid flight activity was monitored using standard yellow water traps. Bean colonising aphids were assessed throughout the vegetation period by counting the number of plants infested with Acyrthosiphon pisum, Megoura viciae and Aphis fabae. Pea enation mosaic virus and bean yellow mosaic virus were the most abundant aphid-transmitted viruses, being detected in 22,54% and 9,69%, respectively, of the total number of virus-infected plants analysed per year. Further aphid-transmitted viruses found in faba bean were bean leaf roll virus, beet western yellows virus, clover yellow vein virus (in 2002) and soybean dwarf virus (in 2004). A. pisum was the predominant aphid species colonising faba bean plants. Early sowing compared with late sowing led to a significant reduction of the total virus incidence in faba bean in all 3 years. However, significantly decreased levels of A. pisum colonisation as a result of early sowing were observed only in 1 year and one cultivar. Irrespective of sowing date, straw mulching had no significant effects on virus incidence and aphid colonisation. Compared with late sowing, early sowing significantly increased bean yield in all 3 years and kernel weight in 2 years, whereas straw mulching had no effect on yield. [source]


Evaluation of Transgenic Poplars Over-Expressing Enzymes of Glutathione Synthesis for Phytoremediation of Cadmium

PLANT BIOLOGY, Issue 6 2002
A. Koprivova
Abstract: Recently, phytoremediation of soils polluted with heavy metals has received a lot of attention. Since glutathione (GSH) and its derivatives (e.g., phytochelatins) play a major role in plant defence against environmental pollutants, we tested the effects of over-expression of bacterial genes for GSH synthesis in poplar on cadmium accumulation. A pilot experiment with CdCl2 in hydroponics revealed that poplars over-expressing ,-glutamylcysteine synthetase (,-ECS) accumulated significantly more Cd in root tissue than wild type or glutathione synthetase over-expressing poplars. To test the partitioning of Cd in different organs, poplar lines over-expressing ,-ECS in the cytosol and in chloroplasts were treated with 0.2 mM CdCl2 in hydroponics. Significant amounts of Cd were translocated to leaves, but significant differences in Cd accumulation were not observed between transgenic and wild type plants. To evaluate these lines for large-scale phytoremediation of cadmium, plants were treated with 2 mM Cd in soil. Over a four-week period, the poplar plants were able to accumulate up to 5.3 mg Cd. Most remarkably, in young leaves of both transgenic lines, Cd was accumulated to concentrations 2.5 - 3 times higher than in the wild type. The increased allocation of cadmium to the young leaves represents a potentional advantage for the phytoremediation process using the same plants over several vegetation periods. The use of transgenic poplar lines with enhanced glutathione production capacity seems to be of particular advantage in highly polluted soils. [source]