2004 * XV * 2

V. Geherman, A. Parol.  
  Väetamise mõjust erinevate karjamaakoosluste saagikusele ning rohu söödavusele ja kvaliteedile 67

The influence of fertilisation on yielding ability of different pasture communities, grass quality and edibility by cows. The main objectives were to study the forage legumes (in the mixture with grasses) yielding ability and quality, intake by cows at grazing conditions in sown grassland and in long-term fallow of no fertilisers, mineral and organic fertilisers area. The trial was carried out on the experimental station of EAU on podzoluvisols in 2001–2003. The experiment included 14 treatments: 12 were sown with 4 different grass seed mixtures and 2 treatments was fallow (20 years outside use). In the sowing year (2001) the climate conditions were very favourable for grass seeding and growth (rainfall 430 mm in May-September). The first grazing year (2002) was extremely drought (the rainfall for the growing season was only 186 mm). The next year there were good weather conditions (the total precipitation 475 mm). The established grass sward average density was 3000–6000 tillers per m2 and the same for long-term fallow sward was 2000 tillers per m2. The proportion of legume species in swards at grazing was following: tetraploid red clover cv. Ilte (58–81%), the alfalfa and white clover 47–76% and 37–74%, respectively. The highest annual yields were obtained in puregrass sward (7.7–8.7 t DM ha-1) with mineral fertilisation and with grass-legume mixtures (7.0–7.4 t DM ha-1). The results of the experiment showed that cows eat herbage selectively from the sward. The degree of herbage utilization by cows (% of maximum) was in white clover mixture (75–85%), long-term fallow (74–87%) and red clover (64–78%) swards with mineral fertilisers and non-fertilised. Lowest use of grass by cows was observed in pure grass (17%) and in alfalfa (27%) swards with manure fertilisation in 2002. The biggest amount of herbage eaten by dairy cows per day (13.5 kg DM cow-1) was obtained from the fallow sward. The smallest amount (0.7 kg DM) was from the sward of pure grasses sown on manure fertilisation background. The CP content in grass DM ranged from 7.9 to 20.4%. The highest content of protein was reached with the lucerne treatment in 2003.

Keywords: dry matter, edibility, fresh herbage, grazing, intake, legumes

J. Kadaja.  
  Kartuli produktsiooniprotsessi dünaamiline mudel ja selle rakendused 74
Dynamic model of potato production process and its applications. The method of reference yields is described as a conceptual basis for composing models of agricultural crops. This method considers four yield levels: potential yield (PY), meteorologically possible yield (MPY), actually possible yield (APY) and commercial yield (CY). PY expresses the radiation resources, MPY the agrometeorological or agroclimatic resources and APY the soil resources for cultivation of variety in the units of yield.

This concept is applied in the dynamic model POMOD for modeling potato production process and yield. In present state POMOD allows computing PY and MPY. Model is based on balance equations and takes into consideration photosynthesis, respiration and growth. Photosynthesis is calculated by hourly steps on the basis of distribution of solar radiation inside the canopy. Respiration consists of maintenance respiration and growth respiration. Growth of plant organs is calculated using differential or integral functions of growth. The time step of growth is one day. MPY is calculated taking into account air temperature and soil moisture. The last is computed by the equation of water balance. The model was verified against field observations and data of variety network. Its sensibility was analyzed regarding variations in photosynthesis parameters and the averaging level of meteorological data.

The model has been applied in evaluation of agrometeorological, agroclimatic and radiation resources for potato cultivation in Estonia, other Baltic Republics and Komi (the last at the northern boundary of potato cultivation area). The model has been as basis in working out the method of probabilistic yield forecasts and in evaluation of climate change impact to the potato cultivation, it has been used as instrument for different model experiments.

Keywords: production process, dynamic model, potato, reference yields, growth functions, model applications, PAR, soil water content, temperature.

H. Kaldmäe, A. Olt, M. Vadi.  
  Liblikõieliste heintaimede proteiini lõhustuvusest 90
Protein degradability of legumes. Kinetics of ruminal protein degradability of fresh lucerne and red clover, and that of silage prepared from them, also the effects of legume species, variety and additive on silage degradability were studied. Test silage from hybrid lucerne varieties 'Karlu' and 'Jõgeva 118', and from red clover varieties 'Jõgeva 433', 'Varte', 'Jõgeva 205' and 'Ilte' were conserved into 3-litre jars at early bloom stage. Protein degradability was investigated by the method of in sacco with fistulated cows.

The protein degradability of fresh grass and that of silage from the same material are different. The effective degradability of fresh red clover was 67% and that of red clover silage 75%; the same values for hybrid lucerne were 77% and 85%, respectively.

The effective protein degradability of silages from different lucerne varieties varied from 82 to 85% and that from red clover varieties from 74 to 77% at the same stage of development. A chemical additive slowed down silage protein degradability in the rumen to 16 incubation hours and decreased the effective degradability by 2%, compared to the silage prepared without an additive. Silage protein degradability in the rumen is affected by legume species and to a lesser degree by a variety.

Keywords: legume, silage, protein, degradability, lucerne, red clover.

K. Kask, M. Jalakas.  
  Maguskirsipuu talvekahjustused Rõhu katsejaamas 1998–2003 96
Winter damages of sweet cherry trees at the Rõhu Experimental Station 1998–2003. The sweet cherry breeding programme of the Polli Horticultural Institute of the Estonian Agricultural University resulted in laying down of 19 new selections which were planted into the experiment at the Rõhu Experimental Station. For comparison 4 Estonian cultivars of earlier breeding activities, 1 selection of an amateur breeder of Estonia, and 3 foreign cultivars were also included into the experiment.

The following cultivars (in quotation marks) and selections are dealt with: 'Dönissen's Gelbe Knorpelkirsche' (German origin), 'Leningradskaya Chernaya' (Russian origin), 'Gronkavaya' (Belarus origin), and the Estonian-origins Anne, Eda, Elle, Elo, Eva, Juku, Kadrin, Kalju, Karmel, 'Kristiina', Madissoni Roosa, 'Meelika', Mupi, 'Nord', Piret, Polli Murel, 'Priima', Taki, Tontu, Tõmmu, Nr. 2-2, Nr. 5-1, Nr. 6-1, and Nr. 12-5. All 27 cultivars and selections on the Prunus mahaleb rootstock, were planted in 1998 at the distances 3×4 m. The main differences in winter hardiness were evaluated after a severe 2001/2002 winter damage through (a) the per cent of total destroy (killed trees) and (b) the per cent of trees with entirely healthy trunk and shoots. Conclusive judgement were made in the next autumn (2003), when the aftereffect was apparent. The strongest damages were stated in 'Gronkavaya', Eva, Juku, Kalju, Karmel and Tõmmu. On the contrary, Mupi, 'Nord', Nr. 12-5, Elle, Madissoni Roosa, and 'Leningradskaya Chernaya' demonstrated the best winter hardiness. Two cultivars 'Kristiina' and 'Meelika' of Estonian origin differed in good per cent of overwintered trees with healthy trunk, but in the same time, considerable per cent of trees were killed. Tontu had almost the same result.

Keywords: sweet cherry, winter hardiness of 27 cultivars and selections

K. Kolk, R. Pällin, T. Kärner, O. Oraste.  
  Astelpaju koduaiakultuurina 102
Sea buckthorn as a home garden crop. Sea buckthorn is known as a very rich source of vitamins. In particular, by the concentration of carotene and ascorbic acid (vitamin C) and vitamin E, seabuckthorn berries are among the 5 first foodstuffs. Antioxydative effect of sea buckthorn berries has been observed, even though scientific information about this effect is not complete. The concentration ascorbic acid and carotene in sea buckthorn berries and in juice has been determined during 3 consequtive years, and investigated its dependence on the cultivation area, on the ripening stage, on the size of berries.

Keywords: sea buckthorne, ascorbic acid (vitamin C), karotene

E. Lauringson, H. Vipper, L. Talgre.  
  Agrotehniliste võtete mõju mulla füüsikalistele omadustele 107
The effect of farming techniques on soil physical properties. This research was conducted at the trial fields of the Department of Field Crop Husbandry of the Estonian Agricultural University. The trial was carried out on the moderately moist slightly podzolised sandy clay soils of the experimental field over 16 years (1982–1997). The effect of farming techniques was investigated in three eight-field crop rotation systems (the first round of rotation in 1982–1989, the second in 1990–1997).

Farming techniques are important determinants of soil properties. The soils of south and central Estonia, with their relatively low humus content and poor texture, thicken quickly and are therefore vulnerable to treading. Consequently, short-term measures are insufficient to improve them. The inclusion of mixture of red clover and timothy in crop rotation improved soil hydrophysical properties and increased the share of waterproof aggregates in soil texture. The improvement of texture is attributable first and foremost to the great root mass of mixture of red clover and timothy in the soil. The growth and root mass of mixture of red clover and timothy depended on the depth of autumn ploughing prior to the sowing of the cover crop (barley) (r=0.95**). The effect of crop rotation on soil physical properties was more evident before spring tillage.

The differentiation of soil bulk density in the ploughed layer was most evident in the rotation of cereals. Abundant use of organic fertilisation (in the cereal-potato rotation) and larger amounts of plant litter (in the cereal-mixture of red clover and timothy-potato rotation) ensured higher humus content and more favourable physical properties for the soil.

Loosening with stubble cultivator compared to ploughing ensured better soil hydrophysical properties only in the 0–8 cm soil layer. Water content in the 16–24 cm layer did not differ under different tillage techniques; however, ploughed soil evidenced better aeration.

Keywords: crop rotation, soil tillage, soil bulk density, ploughing, stubble cultivator, loosening.

K. Reidla, A. Lehtla, V. Andrianov.  
  Laserteraapia kasutamisest eksperimentaalsete luumurdude paranemise kiirendamiseks küülikutel 119
The application of laser therapy to accelerate the healing of experimental bone fractures in rabbits. Bone fractures are among the most severe and complicated pathologies, their treatment is long and challenging complications often occur. The stimulation of the bone tissue regeneration is a crucial factor determining the speed of recovery. In the current experimental study, the acceleration of the bone tissue regeneration was stimulated with laser beams by applying laser therapy with laser apparatus Agnis-L01 in rabbits with experimental bone fractures. Laser Agnis-L01 is semi-conductive impulse-laser with emission frequency close to the infrared light. In total 97 rabbits in 10 series were included into the experimental study, experimental pairs were formed – one rabbit received active treatment (experimental animal) and the one served as the control animal (in 1 series an animal served as control for 2 experimental animals). A bone defect was experimentally induced to radius of both experimental and control animals. The healing and recovery was assessed clinically and radiologically. The effect of varying parameters of laser therapy was assessed. Different parameters appeared to produce varying results. The impact of laser Agnis-L01 on the healing and recovery of bone fracture had the best effect when following parameters were applied: impulse power 1,5 W, impulse frequency 200 Hz, modulation frequency 50 Hz, duration of exposure to the laser beams during a session 240 seconds, number of influenced points 5, treatment frequency of 1 session a day, 10 treatment sessions in total. The treatment was initiated on the fourth day after the induction of the fracture. The treatment was effective, and healing and recovery complete in 71,4% of the treated animals, it did not show any effect in 14,3% of the animals and in 14,3% seemed to affect the recovery process negatively.

Keywords: laser-therapy, bone fracture, rabbit.