2000 * XI * 3

K. Annuk.  
  Taimekasvatuslikust katsetegevusest Eestimaal ja Põhja-Liivimaal XIX sajandil ja XX sajandi kahel esimesel aastakümnel. 3. 193
On plant growing experiments in Estonia and Northern Livonia in the 19th century and the first two decades of the 20th century.

Experiments in manors and farmsteads. In the 1st half of the 19th century the fertilizing tests and various other agrotechnical experiments were first performed in manors, later on in numerous farmsteads. Multiple manurial experiments and variety comparison tests have been carried out. Potato and clover emerged as new field cultures.

M. Agur, V. Rosenberg.  
  Kartuli merikloonide resistentsus KVM-le ja selle sõltuvus opereeritava meristeemi lokalisatsioonist taimel 200
Resistance of potato meristimic clones to PVM and it dependence from the localisation of the operated meristem in the plant. The susceptibility/resistance to the potato virus M (PVM) and the intensity of PVM biosynthesis in the meristemic clones of the same cultivar as well as in the meristemic clones regenerated from the meristems operated from different parts of the same plant (apical and lateral buds of shoot, immatural bud of flower) were studied. The named resistance characteristics to PVM in 27 meristemic clones of 4 potato cultivars (Premiere, Eba, Kondor, Vigri) was compared. The differences in the degree of susceptibility and intensity of virus biosynthesis in meristemic clones of the same cultivar, i.e. of genetically homogeneous material, were established. The most resistant meristemic clone-virus combinations for each cultivar studied were selected to get the prospective initial material for seed potato production. The highest relative resistence to PVM was found in meristemic clones Eba 1000, Kondor H, Premiere 356, and Vigri 918.

The dependence of virus resistance of the potato meristemic clones on the location of operated meristem in the plant was established. 13 meristemic clones of four cultivars (Kondor, Eba, Premiere, Varane kollane) have been analysed. All varieties showed the highest degree of the intensity of virus biosynthesis and susceptibility to PVM in the meristemic clones obtained from an apical bud of shoot, and the lowest one in the clones from a lateral bud of shoot. As a source for an initial material for producing seed potato more resistant to PVM, the meristemic clones regenerated from meristems operated from lateral bud of shoot were recommended.

In both experiments the inoculated plants (1st year) and their second generation (2nd year) were analysed. In the 2nd year the degree of the intensity of virus biosynthesis and susceptibility to virus infection were higher than in the 1st year, however, the relative differences between the meristemic clones of the cultivar remained the same.

In our earlier experiments analogous differences in the characteristics of resistance of the potato meristemic clones infected with PVX were established. It means, the differences in susceptibility/resistance and virus biosynthesis intensity in the meristemic clones of the same variety and dependence the degree of these characteristics on the localisation of the operated meristem in the plant is typical at least to two potato viruses (PVM, PVX).

J. Kasesalu, A. Laius, K. Lotman.  
  Dermocystidium’i perekonna parasiitide esinemine ja liigiline koosseis Eesti kalamajandeis ja mõnes looduslikus veekogus 205
The occurrence and species composition of parasites of genus Dermocystid-ium in Estonian fish farms and some natural water bodies. During 1996…1999 3368 fishes from nineteen species were investigated by the mean of complete parasitological dissection in twelve fish farms and in five natural water bodies of Estonia. The cysts of Dermocystidium were found in fish farms on common carp, rainbow trout and roach and in natural water bodies on pike and perch. The Estonian parasite fauna was complemented by four species: on common carp — Dermocystidium cyprini Červinka et Lom, 1974; on pike — Dermocystidium vejdovskyi Jirovec, 1939; on perch — Dermocystidium percae Reichenbach-Klinke, 1950 and on rainbow trout — Dermocystidium species. Of parasitologically investigated common carps 18.4% of them were invaded by the cysts of Dermocystidium cyprini during four wintering periods and in one of the fish farms even 24.6% of fishes were invaded. The highest invasion by the cysts of Dermocystidium cyprini occurred in March when almost a quarter (23.4%) of investigated common carps were invaded. The highest intensity of invasion was also regis-tered in March when 18.7 cysts per fish on an average were recorded. The maximum quantity of cysts per one fish reached up to 78.

Key words: Dermocystidium, parasitological investigation, cyst.

R. Kask.  
  Eesti muldade orgaanilise aine sisalduse ja koostise uurimisest, ajalooline ülevaade 213
Research of the content and composition of organic matter in the Estonian soils: a comprehensive historical survey. A detailed survey of the research history of the content and composition of organic matter in the Estonian soils, carried out at the Institute of Soil Science and Agrochemistry at the Estonian Agricultural University and its forerunners, has been provided in an article by R. Kõlli, I. Lemetti, A. Kanal, and P. Penu (1996). The present article complements that information by relevant studies completed at other research centres, such as the Tooma Experimental Moor Station and its legal successors, the Estonian Agricultural Institute and its forerunners, the Estonian Forest Institute, the Republican Station of Chemicalization and its legal successors, the State Project Institute "Eesti Põllumajandusprojekt", the Department of Soil Science and Agrochemistry at the Estonian Agricultural University.

The publishing history of the most essential studies on the organic matter of the Estonian soils is as follows:

  • The first data on the content of organic matter (Corg) were published by A. Wegesack (1912, for peat soils) and A. Nõmmik (1925, for mineral soils);
  • The humus content of different soils (taxons) is characterised on the example of typical representatives of the taxons – A. Lillema (1958); on the basis of massive testing results, providing the more frequent percentage intervals – A. Piho, R. Kask (1960), and as a result of statistical processing – R. Kask (1975) and State Project Institute "Eesti Põllumajandusprojekt" (Eesti…, 1978, 1985).
  • For the first data on the composition of the humus of mineral soils – G. Šabalina (1960, 1963). Statistically processed material is represented by R. Kask (1970, 1975)
  • The impact of organic matter on various soil characteristics can be found in the following sources, respectively: density (E. Reppo, 1968); bulk density (R. Kask, 1997); water capacity (L. Bergert, 1972, R. Kask, 1975, E. Kitse, 1978); physical and chemical properties (R. Kask, K. Kripson, 1969, R. Kask, 1975);
  • The supply of organic matter in different soils has been studied by E. Kitse, R. Leis (1996) for arable lands, and by R. Kask (1997) for non-arable lands;
  • The changes of organic matter content and supply depending of land use – A. Truu et al. (1969); U. Tomberg (1989); R. Kask et al. (1989, 1992); T. Valgus (1989); R. Kask (1999).
  • The impact of the organic matter content on soil fertility is demonstrated by R. Kask (1975, 1994).
  • For comprehensive regular testing of the humus content of arable lands – Republican Station of Chemicalization; (E. Raudväli, L. Kevvai 1990).
N. Koslov, E. Lepp, V. Lokk, J. Song, T. Kirtsi, T. Järveots.  
  Klamüdioosi epizootoloogia, etioloogia, patogeneesi ja patoloogiliste muutuste uurimine erinevatel loomaliikidel Eestis 219
Investigation of the epizootology, etiology, pathogenesis and pathological changes of chlamydial infection in various species of animals in Estonia. As has been established in chlamydial animals chlamydiae are localized also in the central nervous system – in the brain and spinal cord. On the basis of the investigations of the brain and spinal cord applying the immunofluorescence method chlamydia have been found in cattle, pigs, horses, sheep, rabbits, guinea-pigs, dogs, cats, arctic foxes, caged minks (Mustela vison), white rat, mice, hens, pigeons, elks (Alces alces), wild boars (Sus scrofa), pine martens (Martes martes). Chlamydiosis has been detected also in perinatal and older calves as well as in full-grown cows. Chlamydial infection was most often found in perinatal calves which died before the 7th day of life (52.4%). Cerebral investigations had revealed chlamydiosis also in pigs which died at different ages, in most cases perinatally – stillborn and 1…3-day-old piglets – 84.2%. In piglets which died at an older age and pigs which died at the age of 1…6 month the incidence of chlamydial infection was lower, but still noticeably high – 41.2…55.6%. Chlamydiae were also found in the samples taken from the brain and spinal cord of butchered pigs in abattoirs and carcasses in meat markets.

The occurrence of chlamydiae was also established in the brain and spinal cord of wild animals. Of the eight investigated elks the samples from the spinal cord revealed chlamydiae in six animals (75%), of the five investigated wild boars the samples from the spinal cord of three animals and those from the medulla oblongata of one animal showed the occurrence of chlamydiae (80%), they were also found in the samples from the spinal cord of one pine marten. We were not able to isolate chlamydiae from the brain in cell cultures, neither did we succeed in determining their species. The gross pathology in the calves discussed in the present research did not differ from that published earlier (Koslov, 1996). Chlamydial pathological changes were not observed in pigs, besides, the number of dissected animals was too small to make definite conclusions. In the animals affected by chlamydiae (calves, piglets, a sheep, a cat, elks, wild boars) no gross pathology was observed in the brain or in the spinal cord, however, histological examination revealed scrapie-like vacuolar (spongiform) changes in the brain and spinal cord.

Key words: chlamydiae animals, brain, spinal cord, scrapie-like changes.

E. Lauringson, T. Kuill, H. Vipper, L. Talgre.  
  Mahajäetud põllud biosüsteemis 232
Abandoned fields in biosystem. This research work is based on research as well laboratory work at the Department of Field Crop Husbandry at the Estonian Agricultural University between 1996 and 1999. The main research subjects were the herbage immediately created after cultivation was stopped on abandoned fields, its composition by species, the dynamics and pushing ahead of dominant species, the soils general and developable seed supplies, the placement of this in ploughed layers as well as the amounts and the viability from the effects of phytosynosis.

Along with the interruption of cultivation came a self-regulating blanket of plant coenosis, where from the first growth together of a species with an age of up to 5 years, characterizes those accountable as annual species (38.6…56% of the sum of the plants), relatively sparse plant cover (103…272 stem m-2) and modest density in the numbers of species together (5–10 plants per subject). The results are influenced by the weediness of the crops prior to the cessation of cultivation, the density of species and their frequency. Following grain crops, these species were the most frequent Tripleurosperum inodorum (L.) Schultz-Bip., Polygonum lapathifolium L., Viola arvensis Murr., Vicia hirsuta L., Chenopodium album L. Annual species as well as the perennial species Agropyron repens (L.) Beauv. On weedy hay fields, the first species in frequency were Agropyron repens (L.) Beauv. and Taraxacum officinale Wigg.

On older fields with an age of over 5 years Agropyron repens (L.) Scop. turned out to be dominant of short stemmed and stalked with amounts up to 1712/m-2 (Annikoru, 1999). On many of the research areas, there appeared among the plant coenosis Cirsium arvense (L.) Scop. a center of spreading as well as Artemisia vulgaris L. wide spread. In older phytosynosis this meant that there was a sharpening of competition within and among the different species. The amount of annual species among the plant coenosis had lessened from 5 to 10%. The numbers of weed seeds in ploughed layers (30 cm) were found in numbers of up to 665 600 per m-2 (beach subject), in which up to 50.6% of the seeds taken into account were found on the surface of the soil. The main part of the weed seedbanks were made up of annual species in 1997, 73.6% and in 1998, 72.1% of the total of developing seeds.

In 1997 and 1998, species with a many year longevity dominated our observation fields, annual species’ seeds in the soil. The competitive ability of the dominating species, their adaptability to environmental changes (fertility of the soil, water and air conditions) as well as their correspondence to the species’ biological unusualities caused one-way changes in the plant coenosis as well as the quick replacement of one species with another.

The production of organic material on abandoned fields, it’s placability and dynamics were researched on rowed observation fields. The sum phytomass produced by plant coenosis was made up of stalks’ mass 16.6%, dead plant parts on the surface 14.3%, and rhizomes and roots in the soil, 69.1%. The biggest contributor to the stalk masses was the medium and top layer species Cirsium arvense (L.) Scop., Sonchus arvensus L., and Artemisia vulgaris L., the rhizome and root mass depended mainly on the part of Agropyron repens in phytosynosis.

The high content of sand and gravel in the soil lessened the production of organic material, as well as layers of soil accidentally created when cultivating the soil, and for the lighter soil layers this was achieved by a lasting drought with a high temperature.

The production of organic elements had a positive effect on the fertility of the soil of abandoned fields. The fullest possible realization of this should in the future be a question of research in putting abandoned fields into balance. The research work of 1996–1999 of the actuality and dynamics of plantcoenosis on abandoned fields will enable us to set up the production of effective recultivating technology in the near future.

A. Jerešiūnas, K. Triukas.  
  Toxy-Nil Plus Dry efektiivsus nuumsigade ratsioonis 249
Efficacy of Toxy-Nil Plus Dry in the Diets for Fattening Pigs. Feeding mycotoxin-containing feeds to fattening pigs reduced the growth performance by 3,4% and increased feed consumption per kg gain by 3.3%. Feeding zearalenone-containing feeds caused clinical signs characteristic to this mycotoxin in 1.5 months. Supplementation of diets with Toxy-Nil Plus Dry (1.5 kg/t) increased daily weight gain of pigs by 8.9% and reduced feed consumption per kg gain by 6.8%. The usage of this product did not decrease the carcass and meat quality and was beneficial to the health of pigs fed mycotoxin-containing feeds.

Key words: mycotoxins, fattening pigs, pig feeding.

K. Annuk.  
  Konstantin Regel – Tartu Ülikooli põllumajandusteaduskonna viies õppejõud 255