Investigation of microbiological processes during long-term storage of grey forest soil samples

I. Malynovska¹, V. Bulgakov² and A. Rucins³*

¹National Scientific Centre, Institute of Agriculture of NAAS of Ukraine, 2 b, Mashinobudivnikiv Str., Chabany vil., Kyiv- Svyatoshin Dist., UA08162 Kyiv Region, Ukraine
²National University of Life and Environmental Sciences of Ukraine,
15 Heroiv Oborony Str., UA03041 Kyiv, Ukraine
³Latvia University of Life Sciences and Technologies, Institute of Engineering and Energetics, Faculty of Engineering and Information Technologies, Ulbroka Research Centre, 1 Instituta Street, Ulbroka, Ropazu Region, Stopinu Municipality, LV2130 Latvia
*Correspondence: adolfs.rucins@lbtu.lv

Abstract:

Investigation of a decrease in the viability of microorganism cells in the soil samples, stored for a long time in an air-dry state, has both theoretical and practical significance since in agrochemistry and the soil science it is a custom to store the soil samples for many years and decades, taking it as an axiom that the properties of these samples remain unchanged. To find out what are the patterns of survival of microorganisms of various ecological-trophic, functional and systematic groups, their viability was studied in samples of gray forest soil, stored for 32 months in an air-dry state. It has been shown that the number of microorganisms of most groups decreases by 42–94 times, the number of polysaccharides-synthesizing microorganisms decreases maximum- by 3,993–18,210 times, depending on the agricultural practices, used in a stationary experiment. the number of spores and cysts decreases. The microorganisms which have the least decrease in the number of colony-forming units of micromycetes and Azotobacter as groups that have forms of surviving unfavourable conditions during storage are spores and cysts. In addition, the physiological and biochemical activity of micromycetes decreases significantly, compared to their activity in the original (initial) fresh soil. During storage the number and share in the total number of melanin-synthesizing micromycetes sharply decreases from 65.8–94.6% to 2.48–5.17%. When storing soil in an air-dry state, the rate of decline in the number of microorganisms depends on the functional affiliation of the group and on agrotechnical techniques that were previously used in the stationary experiments: liming, application of mineral fertilizers, ploughing in the by-products of the predecessor crop in the crop rotation, and the biomass of the sideral crop. The organic matter, ploughed into the soil, promotes the survival of ammonifiers, mineral nitrogen immobilizers, Azotobacter and polysaccharide-synthesizing microorganisms. Ploughing in of crop by-products reduce the number and proportion of melanin-synthesizing micromycetes. Verification of the obtained data, using long-term stored soil samples, is not permissible since microbiological processes occur in the soil during which the soil microbiota consumes the macro- and microelements, present in it, organic and organomineral complexes, including humus.

Key words:

ammonifiers, Azotobacter, micromycetes, number, physiological and biochemical activity, soil, storage

Antennal sensilla in ground beetles (Coleoptera, Carabidae)

A. Ploomi¹, E. Merivee¹, M. Rahi², J. Bresciani³, H. P. Ravn⁴, A. Luik¹ and V. Sammelselg⁵

¹Institute of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014, Tartu, Estonia; e-mail: angela@eau.ee
²Institute of Zoology and Botany, Estonian Agricultural University, Riia 181, 51014 Tartu, Estonia
³Veterinary and Agricultural University, Bülowsvej 13, DK 1870, Frederiksberg C, Denmark
⁴Danish Forest and Landscape Research Institute, Hoersholm Kongevej 11, DK 2970, Hoersholm, Denmark
⁵Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia

Abstract:

The antennal sensilla of male and female ground beetle species Bembidion lampros Hbst., Bembidion properans Steph. and Platynus dorsalis Pont. (Coleoptera, Carabidae) were investigated by using a scanning electron microscope. The filiform antennae of ground beetles consist of the scape, pedicel and 9 flagellomeres. Thirteen different sensillar types were distiguished. These were: four types of sensilla chaetica, two types of sensilla trichodea, six types of sensilla basiconica, pit-organs sensilla coeloconica, and small domes sensilla campaniformia. Sensilla chaetica 4 occur only on the antennae of P. dorsalis, and sensilla trichodea 1 only on the antennae ofBembidion species. No sexual differences in the types of sensilla were found on the antennae of these three species. The possible functions are discussed and three types of sensilla were considered as olfactory, sensilla trichodea 2 and sensilla basiconica 1 and 2. Olfactory sensilla trichodea 2 and sensilla basiconia 1 form clear dorsal and ventral sensillar fields on the flagellomeres, which seems to be common in ground beetles.

Key words: