1998 * IX * 4

O. Saveli.  
  Piima tootmine ja töötlemine on probleemiks 253
H. Jänes, A. Õunmaa.  
  Ploomipuuliigid sordiaretuses 258
Interspecific hybridizations of prunus. Interspecific hybridization between Prunus species is a method for increasing the genetic diversity and genetic resources avail-able for plum improvement. One of the most important selection problem in Estonia is make cultivars with high winter hardness.

This paper gives a brief overview about the most widespread species of Prunus.

Prunus domestica L. plums are hexaploids (2n=48). It is the most widely distributed plum species in Europe. Crane and Lawrence (1936) suggest, that P. domestica orginated as a hybrid between P. cerasifera and P. spinosa. However, several scientists suppose that not all is clear in the origin of Prunus domestica.

Differences in ploidy level between the plum species is the main barrier for interspecific crosses. However, in many cases embryo rescue procedures have been useful in overcoming interspecific hybridization barriers.

P. cerasifera Ehrh. is a diploid (2n=16) and grows both wild and cultivated in Eurasia. It hybridizes easily with other plum species. Many successful crosses were made between P. cerasifera and P. salicina. Cultivars: ‘Kubanskaja Kometa’, ‘Pramen’, ‘Vetraz’, ‘Mara’, ‘Asaloda’ and ‘Vitsba’.

P. spinosa L. is a tetraploid (2n=32). Its growing area is wide: from Western-Siberia and Kaukasus to the Atlantic Coast and from North-America to Mid-Scandinavia. P. spinosa is useful for cold hardness. I. Michurin paid it much attention to P. spinosa, he obtained forms with sweet fruits, which were used as progenitors for a series of new cultivars.
P. salicina Lindl. originated in China. It is a diploid (2n=16). P. salicina hybridizes easily with American plum species. ‘Burbank’, ‘Satsuma’, ‘Abundance’ and ‘Santa Rosa’ were originated by L. Burbank.

P. americana Marsh. is a diploid (2n=16). It is the most widely distributed native plum species in North-America. P. americana Marsh. is reported to carry genes for cold hardness. Estonian cultivar ‘Vikana’ from a cross between ‘Queen Victoria’ and P. americana is a very productive, with large fruits and quite winter-hardy.

R. Kask.  
  Eesti põhiliste haritavate muldade huumushorisondi paksus, selle dünaamika ja mõju mulla viljakusele 264
The thickness of the humus horizon in the main arable soils of Estonia, its dynamics and influence on soil fertility. The thickness of the humus horizon (Aorg-horizon) of Estonian arable soils varies from 10 to 100 cm. The humus horizon is thinner in soils on massive limestone and thicker in deluvial soils. Before 1950 the average thickness of the Aorg-horizon in the main arable soils in Estonia varied from 19 to 27 cm.

Within nearly half a century the thickness of the humus horizon of Estonian light-textured arable soils has increased by a third. The reason lies in a increase in the depth of ploughing and the horizontal displacement of soil particles due to erosion and soil cultivation. Differences in the yield of crops grown on different soils are closely connected with the thickness of the Aorg-horizon, the coefficient r (R) varying from 0,87 to 0,96 (see Table 3).

Considering the relatively rapid increase of the thickness of the Aorg-horizon and its anthropogenic nature it should by no means be recommended for use as an estimate of soil fertility. The influence of the thickness of the humus horizon on soil fertility is sufficiently well reflected in the standard estimates of the taxonomic units of soil classification.

Keywords: the thickness of the humus horizon, arable soil, nonarable soil, dynamics of thickness of arable soil, soil fertility.

R. Kask.  
  Dolomiitsel rähkmoreenil kujunenud muldade omapärast 273
On the specific character of soils formed on dolomite-rich morain. Soils formed on dolomite-rich break-stony morain are distributed across landscape relief similarly to soils formed on limestone-rich break-stony morain. Typically, such soils are found in asso-ciation with leached and podzolized sod-calcareous soils, with a possible addition of residual carbonate sod-podzolic soils and their gleyed forms.

The soils based on dolomite-rich morain are characterised by a relatively higher magne-sium content. Magnesium carbonate is leached more easily than calcium carbonate. In the process of carbonates leaching from the soils on dolomite-rich morain the prevalence of cal-cium over magnesium (CaO : MgO) increases, whereas in the soils on limestone-rich morain it, on the contrary, decreases.

The content of lactate-soluble magnesium in the soils is connected with the total content of dolomite in the parent rock. In Estonia the proportion of soils with a high content of mag-nesium is the largest on the Isle of Saaremaa and in central Estonia where dolomites from the Raiküla and Adavere horizons are found.

Keywords: soil, dolomite-rich morain, limestone-rich morain, sod-calcareous soil, mag-nesium, calcium.

A. Nummert.  
  Instrumentaaluuringute võimalik rakendamine veterinaarias 282
Possibilities for application of instrumental investigation methods in veteri-nary medicine. Instrumental investigations are absolutely necessary both in human and veterinary medicine for proper establishment of diagnoses as well as performing specific treatment. Present study is focused on most important instrumental investigation methods: ultrasonography and fiberoptic endoscopy.

Ultrasonography is one of the most efficient methods in medicine which allows to make proper diagnoses, perform directed needle biopsies and monitor disease dynamics.

Varying success has been reported when ultrasonography was used in veterinary medi-cine by different investigators (W. G. Zoller et al., 1992). Majority of authors recommend to remove hair and apply special gel to minimise air between transducer and skin (L. J. Konde et al., 1984; T. G. Nyland et al., 1985; Nyland et al., 1995). Modern equipment EUB 450 (Hitachi, Japan) allows to use simultaneously liner and convex transducers even without removing hair (I. Kull and A. Nummert, 1996).

Fiberoptic endoscopy is an important invasive method which allows internal visualisa-tion of different organs followed by diagnostic and therapeutic procedures. At present it is the only routine method which allows complex imaging of gastrointestinal and respiratory tracts and is harmless for patients. For this purpose presence of fiberoptic endoscopes, manipula-tion skills as well as good instrument maintenance are needed.

Fiberoptic endoscopy procedures are usually well tolerated and there are no absolute contraindications. Slight premedication and topical anaesthesia are usually sufficient for suc-cessful investigation. Fiberoptic endoscopy allows to collect general visual information about organs, condition of mucosa, pattern of blood vessels as well as nature, localisation and activity of pathological processes. It is possible to collect body fluids and tissue specimens for further microbiological and histological studies by inserting biopsy brushes, needles or forceps via working channel of fiberoptic endoscope. Therefore fiberoptic endoscopy is essential for tumour diagnosis especially in early stages.

Indications for fiberoptic endoscopy in veterinary medicine could be mainly diseases of oesophagus (inflammation, ulcer, foreign bodies). Fiberoptic endoscopy allows to collect general visual information about organs, condition of mucosa, pattern of blood vessels as well as nature, localisation and activity of pathologial processes. It is possible to collect body fluids and tissue specimens for further microbiological, cytological and histological studies by inserting biopsy brushes, needles or forceps via working channel of fiberoptic endoscope. Therefore fiberoptic endoscopy is essential for tumour diagnosis especially in early stages.

Fiberoptic endoscopy could be used also for treatment like local application of drugs, dilatation of stenosis, hemostasis, removal of foreign bodies, etc. Electro-, cryo- or laserther-apy could be used for recanalisation in palliative purposes. Diagnosis and treatment of pathological processes in stomach, duodenum, rectum and colon should be considered as well.

Additional indication for fiberoptic endoskopy in veterinary medicine compared to human medicine could be diagnosis and treatment of endometrial inflammation.

V. Viljasoo.  
  Tehnika Weibulli- ja eksponentjaotusele alluva töövõime määramise metoodika 284
Determining the Weibull and exponentially distributed serviceability of machinery. The determination of machinery serviceability enables to increase its reliability and economic efficiency, to arrange preventive technoservice independent from economic criteria and to fix the level considering the expenses on technoservice and maintenance. The determined serviceability levels enable to define qualitative level of operating machinery, the ratio of defects and failures. The given serviceability levels, calculated by achieved technoservice or restored serviceability maintenance will enable to prognosticate its reliability indices. Thus a greater stress will be put on the quality of technoservice. The given methods can be applied for solving practical problems in reliability of work.
K. Annuk  
  Esmased muljed “Eesti Põllumajandusentsüklopeedia” ehk EPE 1. köitest 290
K. Annuk  
  Akadeemilise Põllumajanduse Seltsi tegevusest 292