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81.
The objective of this study was the calculation of winter chill for fruit trees in the Meckenheim fruit growing region for all winters since 1958 and the evaluation of long-term trends in response to global warming. A further objective was the comparison of three winter chill models, the Chilling Hours Model (Chilling Hours??CH), the Utah Model (Chill Units??CU) and the Dynamic Model (Chill Portions??CP) with respect to temporal trends and seasonal variation in chilling intensity. To meet these objectives, about 120,000 hourly temperature measurements from Klein-Altendorf were correlated with daily temperature extremes. From this relationship, a long-term record of 466,000 hourly temperature data was constructed and used to calculate winter chill between 1st October of each year and three dates of the following year for all winters since 1958/1959. On average over all years, 955 CH, 1160 CU and 58.0 CP had accumulated in the Meckenheim fruit growing region by 1st January, 1356 CH, 1527 CU and 77.3 CP by 1st February, and 1727 CH, 1883 CU and 96.1 CP by 1st March. Coefficients of variation varied between 14 and 16% for the Chilling Hours Model, between 18 and 19% for the Utah Model and between 9 and 10% for the Dynamic Model. In spite of significant warming of the site, no clear long-term trends were detected. Due to the structure of the winter chill models, which do not consider freezing temperatures as chilling-effective, the highest chilling was not registered in the coldest winters, but rather when average temperatures between early December and late February were between 2 and 6°C. The coldest winter on record (1963/1964; mean winter temperature of ??4°C) had by far the lowest winter chill total, and chilling during the more recent cold winters 2009/2010 and 2010/2011 was also below average. Only very pronounced warming reduced winter chill, with the warmest winter on record (2006/2007; mean winter temperature of 7.1°C) accumulating less winter chill than slightly cooler winters. As long as such extreme temperatures remain exceptional, fulfilment of chilling requirements of local apple and cherry cultivars should not become critical. It is important to note, however, that substantial knowledge gaps exist in the field of fruit tree dormancy, which will have to be closed, before more reliable projections of future fulfilment of chilling requirements can be made. 相似文献
82.
Peschiutta María Laura Achimón Fernanda Brito Vanessa Daniela Pizzolitto Romina Paola Zygadlo Julio Alberto Zunino María Paula 《Journal of pest science》2022,95(3):1037-1056
Our aim was to perform a qualitative review and a meta-analysis with 57 scientific articles (108 assays) published from 1 January 2000 to 31 June 2021 dealing with fumigant toxicity of essential oils (EOs) against Sitophilus zeamais. The studies were obtained from four electronic databases: Web of Science, SCOPUS, PubMed, and Google Scholar. The survey comprised 107 plant species belonging to 26 different families. Lethal concentration values (LC50) of EOs were included in a random-effect model, and two subgroups were defined: “until 24 h” and “more than 24 h”. The EOs more frequently evaluated were those belonging to Lamiaceae (20.18%), Asteraceae (17.43%), Apiaceae (9.17%), and Rutaceae (6.42%). The global mean value was 21.37 (CI95 16.84–27.12), while the summary mean values of the subgroups were 41.45 (CI95 31.10–55.26) for “until 24 h” and 8.45 (CI95 5.72–12.48) for “more than 24 h”. Most species belonging to Apiaceae, Lamiaceae, Asteraceae, and Schisandraceae reported the highest insecticidal effects with mean values that ranged from 1.31 to 27.39 for “until 24 h” and from 0.57 to 5.31 for “more than 24 h”. Additionally, the toxicity of the most effective EOs was discussed by addressing their chemical composition and their major pure compounds chemical features.
相似文献83.
84.
Michael?Mielewczik Michael?Friedli Norbert?KirchgessnerEmail author Achim?Walter 《Plant methods》2013,9(1):30
Background
We present a novel method for quantitative analysis of dicot leaf expansion at high temporal resolution. Image sequences of growing leaves were assessed using a marker tracking algorithm. An important feature of the method is the attachment of dark beads that serve as artificial landmarks to the leaf margin. The beads are mechanically constricted to the focal plane of a camera. Leaf expansion is approximated by the increase in area of the polygon defined by the centers of mass of the beads surrounding the leaf. Fluctuating illumination conditions often pose serious problems for tracking natural structures of a leaf; this problem is circumvented here by the use of the beads.Results
The new method has been used to assess leaf growth in environmental situations with different illumination conditions that are typical in agricultural and biological experiments: Constant illumination via fluorescent light tubes in a climate chamber, a mix of natural and artificial illumination in a greenhouse and natural illumination of the situation on typical summer days in the field. Typical features of diel (24h) soybean leaf growth patterns were revealed in all three conditions, thereby demonstrating the general applicability of the method. Algorithms are provided to the entire community interested in using such approaches.Conclusions
The implementation Martrack Leaf presented here is a robust method to investigate diel leaf growth rhythms both under natural and artificial illumination conditions. It will be beneficial for the further elucidation of genotype x environment x management interactions affecting leaf growth processes.85.
The objective of the MSc project was to improve fruit quality, i.e. fruit firmness, colour and size, by mechanical blossom thinning. Ten-year-old slender spindle apple cv. ‘Gala, Mondial’ trees at Campus Klein-Altendorf near Bonn, Germany with an intense flowering of 7–8 on the 0–9 scale were blossom-thinned on 21 April 2009; unthinned trees served as control. Rotor speeds were 360 rpm or 420 rpm at 5 or 7.5 km/h tractor speed using the new mechanical thinning device developed at the University of Bonn in 2004–2006. Therein, a vertical mast supports three horizontal rotors, whose vertically rotating tines remove excessive flowers; the device was mounted on the front three point hitch of the tractor with the following results:
- Mechanical thinning reduced the number of apple fruit from 18 per branch section in the un-thinned control, 12–13 in the medium to 8 fruit in the strongest thinning (420 rpm, 5 km/h).
- Similarly, the number of singlets (one fruitlet/flower cluster) nearly doubled from ca. 2 per branch in the control to 3–4 after mechanical thinning, as intended.
- The natural June drop after mechanical thinning resembled that in the un-thinned control.
- Mechanical thinning increased fruit mass by 20 g—48 g relative to the un-thinned control.
- Mechanical thinning with 420 rpm increased the portion of premium fruit >?70 mm (class I) by 43?% (7.5 km/h) and 63?% (5 km/h); combined mechanical and hand-thinning yielded the largest portion of fruit >?70 mm (70?%), but with a dramatic loss in yield (55?%).
- Mechanical and manual thinning improved the portion of well coloured fruit (75–100?% coloured) (78–98?%) when compared to the un-thinned control fruits with 55?%, probably due to selective removal of shaded fruits from the inner tree canopy.
- Overall, mechanical thinning alone gave better results than hand thinning alone or its combination with hand-thinning in cv. ‘Gala’; mechanical thinning waived the need for hand thinning in this experiment.
- Mechanical thinning improved fruit firmness from 9.4 kg/cm2 in the un-thinned control to 10.4 kg/cm2.
- Neither vegetative growth nor subsequent fruit drop were stimulated by this type of mechanical thinning.
- The risk of both alternate bearing and over-sized fruit was waived due to the variety employed.
- An economic evaluation showed a net profit of € 220/ha in the weak (420 rpm—7.5 km/h) aνô € 1,844/ha in the intermediate (360 rpm—5 km/h), but a net loss of € 1,120/ha (420 rpm—5 km/h) for the strongest thinning treatment, assuming a cost of € 120/ha for the mechanical treatment and a saving of € 200 for reduced hand thinning.
86.
Philipp Olias Anne Meyer Robert Klopfleisch Michael Lierz Bernd Kaspers Achim D Gruber 《Veterinary research》2013,44(1):10
Pigeon protozoal encephalitis (PPE) is an emerging central-nervous disease of domestic pigeons (Columba livia f. domestica) reported in Germany and the United States. It is caused by the apicomplexan parasite Sarcocystis calchasi which is transmitted by Accipter hawks. In contrast to other members of the Apicomplexa such as Toxoplasma and Plasmodium, the knowledge about the pathophysiology and host manipulation of Sarcocystis is scarce and almost nothing is known about PPE. Here we show by mRNA expression profiling a significant down-modulation of the interleukin (IL)-12/IL-18/interferon (IFN)-γ axis in the brains of experimentally infected pigeons during the schizogonic phase of disease. Concomitantly, no cellular immune response was observed in histopathology while immunohistochemistry and nested PCR detected S. calchasi. In contrast, in the late central-nervous phase, IFN-γ and tumor necrosis factor (TNF) α-related cytokines were significantly up-modulated, which correlated with a prominent MHC-II protein expression in areas of mononuclear cell infiltration and necrosis. The mononuclear cell fraction was mainly composed of T-lymphocytes, fewer macrophages and B-lymphocytes. Surprisingly, the severity and composition of the immune cell response appears unrelated to the infectious dose, although the severity and onset of the central nervous signs clearly was dose-dependent. We identified no or only very few tissue cysts by immunohistochemistry in pigeons with severe encephalitis of which one pigeon repeatedly remained negative by PCR despite severe lesions. Taken together, these observations may suggest an immune evasion strategy of S. calchasi during the early phase and a delayed-type hypersensitivity reaction as cause of the extensive cerebral lesions during the late neurological phase of disease. 相似文献
87.
Achim E. Gau Mostafa Koutb Markus Piotrowski Klaus Kloppstech 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(7):703-711
Leaves of apple (Malus domestica cv. Elstar) were infected with a cloned isolate of the apple scab Venturia inaequalis. The intercellular washing fluid (IWF) of these plants was collected and the variation in the composition of proteins in the IWF was analysed by SDS-PAGE and two-dimensional gel electrophoresis during and after the infection with V. inaequalis, the causal agent of apple scab. The subsequent analysis of induced proteins by electron spray ionization quadrupole time of flight mass spectroscopy revealed the presence of -1,3-glucanase, chitinase, thaumatin-like protein and a cysteine-like protease in M. domestica leaves infected by V. inaequalis. These results were confirmed by immunoblotting with antibodies against some of these proteins. Moreover, a non-specific lipid transfer protein was identified in uninfected leaves: the amount declined to a non-detectable level within the first week after infection by V. inaequalis. The analysis of the IWF of M. domestica cv. Remo, bearing resistances to apple scab, powdery mildew and fire blight, showed a protein pattern comparable to that of the IWF from V. inaequalis infected leaves from cultivar Elstar indicating the constitutive production at least of some of the pathogenesis-related proteins in the resistant cultivar. 相似文献
88.
Carl Fedtke Brigitte Depka Otto Schallner Klaus Tietjen Achim Trebst Detlef Wollweber Heinz‐Jürgen Wroblowsky 《Pest management science》2001,57(3):278-282
The new bleaching herbicidal compound N,N‐diethyl‐N‐(2‐undecynyl)amine (NDUA) is identified here as an inhibitor of lycopene cyclase and is compared with the known cyclase inhibitors N,N‐diethyl‐N‐[2‐(4‐chlorophenylthio)ethyl]amine (CPTA) and N,N‐diethyl‐N‐[2‐(4‐methylphenoxy)ethyl]amine (MTPA). HPLC separation of chloroplast pigments shows lycopene accumulation in NDUA treated tissue. Variation in chain length of the undecynylamine moeity of NDUA from 7 to 21 C atoms reveals an optimum of 11 to 14 C atoms for herbicidal activity. A series of seven further analogues of NDUA and CPTA reveals the structural elements necessary for inhibition of lycopene cyclase. The effect of NDUA derivatives on photosynthesis has been studied in Chlamydomonas reinhardtii. Photosynthesis is highly sensitive, particularly towards the C14 and longer chain length analogues at nanomolar concentrations. It is shown that the breakdown of photosynthesis by NDUA is due to interference with the turnover of the D1 protein of the photosystem II reaction centre that requires the continous biosynthesis of the two reaction‐centre β‐carotene moieties in the reassembly phase. The D1 protein disappearance is most marked under strong light conditions. The depletion of photosystem II occurs before total pigment bleaching. This newly recognized mechanism in herbicidal activity is also the basis for the mode of action of other lycopene cyclase inhibitors as well as phytoene desaturase inhibitors. © 2001 Society of Chemical Industry 相似文献
89.
90.
Lena Gustafsson Mårten Berglind Anders Granström Achim Grelle Gunnar Isacsson Petter Kjellander 《Scandinavian Journal of Forest Research》2019,34(4):234-253
Deepened knowledge on response of biota and ecological processes following fire is essential for a future with warmer climate and more disturbances. In 2014 the first mega-fire (13,100 ha) for at least a century in Scandinavia hit south-central Sweden, in a production forest landscape shaped by clearcutting forestry. Ecological dynamics is followed in >20 projects from universities, authorities and citizen science initiatives, rapidly accumulating substantial amounts of data. We outline projects and summarize their results during the first four years, demonstrating a rapid succession of fungi, lichens, vascular plants, birds, mammals, ticks, butterflies, beetles, and drastically altered carbon dynamics. We characterize forest operations including regeneration measures and point to patterns in pest and pathogen infestations. 8,000 ha is set aside for natural succession, with the rest harvested and managed for forest production, offering excellent opportunities for studies on salvage logging effects, already evident for birds. We demonstrate a strong regrowth of deciduous trees, and the protected part will in some decades likely develop into the largest deciduous-dominated area in boreal north Europe outside Russia. Continued studies of biodiversity and ecological processes are urgent for this unique area. 相似文献