Forest fires and vegetation during the Holocene in central Yakutia, eastern Siberia     

Fumitaka Katamura  Masami Fukuda  Nikolai P. Bosikov  Roman V. Desyatkin 《Journal of Forest Research》2009,14(1):30-36

In order to investigate the relationship between vegetation change and fire history in the Siberian boreal forest, fossil pollen and charcoal from two lakes in central Yakutia, eastern Siberia, were analyzed. The vegetation change inferred from the pollen analysis was similar to that found in previous research in the region. Open larch forest covered this region during the late Glacial and early Holocene periods. Later, during the mid-Holocene, Scots pine expanded its range. The low levels of charcoal in the lake deposits represent surface forest fires, suggesting that the present-day surface fire regime has been taking place since at least 6,500 calibrated years before the present (cal yr BP) and that stand-replacing fire has not occurred during the Holocene. Larch and Scots pine forests, which are characterized by surface fire regimes, have been predominant since the early Holocene.  相似文献   

Persisting soil drought reduces leaf specific conductivity in Scots pine (Pinus sylvestris) and pubescent oak (Quercus pubescens)     

Sterck FJ  Zweifel R  Sass-Klaassen U  Chowdhury Q 《Tree physiology》2008,28(4):529-536

Leaf specific conductivity (LSC; the ratio of stem conductivity (K(P)) to leaf area (A(L))), a measure of the hydraulic capacity of the stem to supply leaves with water, varies with soil water content. Empirical evidence for LSC responses to drought is ambiguous, because previously published results were subject to many confounding factors. We tested how LSC of similar-sized trees of the same population, under similar climatic conditions, responds to persistently wet or dry soil. Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) trees were compared between a dry site and a wet site in the Valais, an inner alpine valley in Switzerland. Soil water strongly influenced A(L) and K(P) and the plant components affecting K(P), such as conduit radius, conduit density and functional sapwood area. Trees at the dry site had lower LSC than trees with the same stem diameter at the wet site. Low LSC in trees at the dry site was associated with a smaller functional sapwood area and narrower conduits, resulting in a stronger reduction in K(P) than in A(L). These observations support the hypothesis that trees maintain a homeostatic water pressure gradient. An alternative hypothesis is that relatively high investments in leaves compared with sapwood contribute to carbon gain over an entire season by enabling rapid whole-plant photosynthesis during periods of high water availability (e.g., in spring, after rain events and during morning hours when leaf-to-air vapor pressure deficit is small). Dynamic data and a hydraulic plant growth model are needed to test how investments in leaves versus sapwood and roots contribute to transpiration and to maximizing carbon gain throughout entire growth seasons.  相似文献   

AHAS Trp574Leu substitution in Raphanus sativus L.: screening,enzyme activity and fitness cost          下载免费PDF全文

Roman B Vercellino  Claudio E Pandolfo  Gabriela Breccia  Miguel Cantamutto  Alejandro Presotto 《Pest management science》2018,74(7):1600-1607

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Creep feeding effects on male Nellore calves influencing behavior and performance of their dams     

Leandro Soares Martins  Mário Fonseca Paulino  Luciana Navajas Rennó  Edenio Detmann  Daniel Mageste de Almeida  Roman Maza Ortega  Deilen Paff Sotelo Moreno  Javier Enrique Garces Cárdenas 《Tropical animal health and production》2017,49(8):1669-1676

The objective of the present study was to evaluate the effect of different schemes of calves’ supplementation in a creep feeding system, on the behavior of Bos indicus calves and dams, and also the influence of the calves’ supplementation on dams’ performance. Forty-eight Nellore male calves (147 ± 7 kg body weight and 3 months of age) in the suckling phase and their dams (476 ± 9 kg and 6 years of age) were studied in a completely randomized design. The experiment was divided into two periods of 71 days. The treatments were 5- and 10-g supplement dry matter (DM)/kg BW day offered in periods 1 and 2, respectively (5S/10S); 10- and 5-g supplement DM/kg BW day offered in periods 1 and 2, respectively (10S/5S); 7.5-g supplement DM/kg BW day in both periods 1 and 2 (7.5S); and mineral mix ad libitum in both periods 1 and 2 (MM). No differences (P < 0.05) in body condition score (BCS), final body weight (FBW), and average daily gain (ADG) were found in dams’ performance. Calves from MM treatment spent more time (P < 0.05) grazing than the supplemented calves from 5S/10S and 10S/5S treatments, in the first period. No difference in suckling time was found between the treatments (P > 0.05) in the first evaluated period. Calves from 10S/5S treatment spent more time suckling and less time eating supplements (P < 0.05) than 5S/10S treatment animals, in the second evaluated period. Dams of MM treatment’s calves had more idle time and lower grazing time when compared with the mothers of calves from 5S/10S and 10S/5S treatments. It was concluded that different schedules of Nellore calves’ supplementation on pasture do not affect their mothers’ performance, and supplementation decreases the grazing time of calves in the suckling phase.  相似文献   

Prediction of pest pressure on corn root nodes: the POPP-Corn model     

Annika Agatz  Roman Ashauer  Paul Sweeney  Colin D. Brown 《Journal of pest science》2017,90(1):161-172

A model for the corn rootworm Diabrotica spp. combined with a temporally explicit model for development of corn roots across the soil profile was developed to link pest ecology, root damage and yield loss. Development of the model focused on simulating root damage from rootworm feeding in accordance with observations in the field to allow the virtual testing of efficacy from management interventions in the future. We present the model and demonstrate its applicability for simulating root damage by comparison between observed and simulated pest development and root damage (assessed according to the node injury scale from 0 to 3) for field studies from the literature conducted in Urbana, Illinois (US), between 1991 and 2014. The model simulated the first appearance of larvae and adults to within a week of that observed in 88 and 71 % of all years, respectively, and in all cases to within 2 weeks of the first sightings recorded for central Illinois. Furthermore, in 73 % of all years simulated root damage differed by <0.5 node injury scale points compared to the observations made in the field between 2005 and 2014 even though accurate information for initial pest pressure (i.e. number of eggs in the soil) was not measured at the sites or available from nearby locations. This is, to our knowledge, the first time that pest ecology, root damage and yield loss have been successfully interlinked to produce a virtual field. There are potential applications in investigating efficacy of different pest control measures and strategies.  相似文献   

Insecticidal and repellent activity of selected essential oils against of the pollen beetle, Meligethes aeneus (Fabricius) adults     

Roman Pavela 《Industrial Crops and Products》2011,34(1):888-892

The essential oils from 9 aromatic plants were tested on repellency and mortality of Meligethes aeneus adults. All the tested essential oils caused high mortality of M. aeneus adults in the tarsal tests. The lethal doses after 6 h exposure were ranged between 197 and 1508 μg cm⁻². Essential oils obtained from Carum carvi and Thymus vulgaris were most efficient where LD₅₀ was estimated as 197 and 250 μg cm⁻², respectively.Repellency declined in all the essential oils as a function of time. The longest persistence time was determined for essences obtained from C. carvi and T. vulgaris where significantly the highest repellent index of 65.6% and 63.8%, respectively, was determined. Repellent index lower than 15% was determined for the remaining essential oils.  相似文献   

Comparison of iatrogenic transmission of Anaplasma marginale in Holstein steers via needle and needle-free injection techniques     

Reinbold JB  Coetzee JF  Hollis LC  Nickell JS  Riegel CM  Christopher JA  Ganta RR 《American journal of veterinary research》2010,71(10):1178-1188

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Four New Sulfated Polar Steroids from the Far Eastern Starfish Leptasterias ochotensis: Structures and Activities     

Timofey V. Malyarenko  Olesya S. Malyarenko  Natalia V. Ivanchina  Anatoly I. Kalinovsky  Roman S. Popov  Alla A. Kicha 《Marine drugs》2015,13(7):4418-4435

Three new sulfated steroid monoglycosides, leptaochotensosides A–C (1–3), and a new sulfated polyhydroxylated steroid (4) were isolated from the alcoholic extract of the Far Eastern starfish Leptasterias ochotensis. The structures of compounds 1–4 were established by extensive nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESIMS) analyses and chemical transformations. Although the isolated compounds did not show any apparent cytotoxicity against melanoma RPMI-7951 and breast cancer T-47D cell lines, leptaochotensoside A (1) demonstrated inhibition of T-47D cell colony formation in a soft agar clonogenic assay at nontoxic doses. In addition, this compound decreased the epidermal growth factor (EGF)-induced colony formation of mouse epidermal JB6 Cl41 cells. The cancer preventive action of 1 is realized through regulation of mitogen-activated protein kinase (MAPK) signaling pathway.  相似文献   

Impact of Stolbur Phytoplasmas on Potato Tuber Texture and Sugar Content of Selected Potato Cultivars     

Kerstin Lindner  Norbert U. Haase  Marinela Roman  Erich Seemüller 《Potato Research》2011,54(3):267-282

Potato stolbur is a phytoplasmal disease that seriously affects yield and tuber quality in South Eastern Europe, Russia and the Mediterranean areas. In 2007 and 2008, field experiments were carried out to determine stolbur resistance of processing potato cultivars at Sannicolau Mare (Romania) by determining consistency and concentration of reducing sugars (fructose and glucose), sucrose and phytoplasmas in potato tubers. In both years, non-symptomatic potato tubers showed sucrose levels in the range of 3,000 mg kg⁻¹ fresh weight (FW). In contrast, sucrose concentrations were up to 11,820 mg kg⁻¹ FW in 2007 and 19,560 mg kg⁻¹ FW in 2008 in tubers showing severe symptoms. These high values severely affect suitability of tubers for processing as sucrose serves as substrate for the formation of reducing sugars that are the limiting factor in fried potato production for Maillard-related discolouration. The cultivars examined differed considerably in susceptibility to stolbur disease. Whereas cvs. ‘Courage’ and ‘Lady Rosetta’ showed high numbers of diseased tubers and high sucrose concentrations, ‘Lady Claire’ had a lower incidence of symptomatic tubers and lower sucrose concentrations. However, fully resistant cultivars were not observed. Across all cultivars examined, phytoplasmal concentration was significantly higher in symptomatic tubers than in non-symptomatic ones.  相似文献   

Drought stress tolerance in common bean: what about highly cultivated Brazilian genotypes?     

C. C. Dipp  J. A. Marchese  L. G. Woyann  M. A. Bosse  M. H. Roman  D. R. Gobatto  F. Paludo  K. Fedrigo  K. K. Kovali  T. Finatto 《Euphytica》2017,213(5):102

Drought stress on reproductive stages constitute a major problem for common bean (Phaseolus vulgaris L.) production because it affects flowering and pod-filling processes which are highly drought-sensitive. In this study, we used a greenhouse experiment to evaluate the response to drought stress in ten highly cultivated Brazilian genotypes in response to moderate intermittent drought during flowering and pod-filling periods (R7 and R8 stages). Morphological, biochemical, physiological and agronomic traits were used to identify tolerant cultivars and elucidate their strategies to cope this stress. The drought intensity index for the experiment reached 0.63. The cultivar IAC Imperador can be defined as a tolerant cultivar, presenting the lowest grain yield reduction (43%) and a reduced drought susceptibility index (0.65). This cultivar elevated their level of proline in roots under stress, which allowed the osmotic adjustment and the maintenance of an intermediate stomata closure during the day, which maintained the intrinsic WUE stable in NS and DS conditions. In addition, this cultivar was able to mobilize the assimilated carbon for the production of pods and grains, evidenced by the high harvest index and the high grain filling index. In this way, IAC Imperador can be used as a check in breeding programs to identify and select lineages with drought tolerance in common bean.  相似文献