Blueberry cultivation is becoming more and more popular in Latvia, and several commercial plantations have been established recently. Highbush blueberries (Vaccinium corymbosum L.) are perennial and can grow without replanting for 50 years; therefore a choice of soil and its preparation have a great role. This article summarizes results of research carried out in commercial blueberry plantation established in 2004 on loamy Haplic Cambisol. Soil properties, especially reaction and organic matter content, initially were not suitable for blueberry cultivation, therefore deep tillage and application of soil conditioner (acid sphagnum peat) were done before planting and similar peat mulch was applied every second year. Berry yield of 4 blueberry cultivars, soil properties and the nitrogen, phosphorous and potassium content in growing plant leaves were determined. The obtained results showed that sphagnum peat is an effective material for lowering of soil pH in plant root layer (0 – 40 cm). Data about plant nutrient content in topsoil and subsoil as well as in growing plant leaves will help to develop criteria for soil fertility assessment and diagnosis of plant nutrition.

The American cranberry (Vaccinium macrocarpon Ait.) is a perspective and marketable crop both in Latvia and foreign markets, but berries are affected by rot in storage. The aim of the study was to detect the incidence level of cranberry fruit rot at the beginning of storage period in different places in Latvia. In 2007 - 2011, two hundred sound berries (out of 1000) were randomly collected by hand along a diagonal from five different cranberry plantations from locations all over Latvia. Berries were kept in plastic bags for a month and refrigerated at +7 °C. At the end of November, berries were sorted and rotten berries were separated from the sound ones. Over the period of 2007 - 2011, the incidence of storage rot reached 12 - 15% at the end of November, with an upwards trend observed every year, but the hot and rainy summer of 2010 significantly reduced the quality of fruit in storage, peaking on the average 33% of decayed berries. The incidence of fruit rot varied among the inspected cranberry plantations, but a tendency was observed that older plantations produced more rotting fruit and incidence of the disease was 12 - 50% after a month’s storage in the oldest plantation. The application of fungicides during the vegetation season did not affect development of post-harvest rot. Storage rot was a problem in the cranberry samples from all inspected plantations in Latvia, and in future the incidence of fruit rot is expected to increase.

The rowanberries (Sorbus aucuparia L.) are small orange-red fruits of a rowan tree and belong to the family Rosaceae. These berries have been described as an important source of flavonoids, and their antioxidant activity affects reactive oxygen species and lipid peroxidation; therefore they are suitable for production of health-food products. The ripe wild rowanberries have traditionally been used for jellies and jams, but their use as a food ingredient has been less popular because of their bitter taste. Sweeter and less astringent than wild rowanberries are different cultivars of sweet rowanberries and hybrids with other species. The aim of the current research was to determine physical and chemical parameters and sensory properties of rowanberry marmalades. The experiments were carried out in the Faculty of Food Technology of Latvia University of Agriculture. The purees of wild rowanberry and six different rowanberry cultivars were chosen for the production of marmalades. Chemical, physical and sensory indices of the product – moisture, total carotenoids, tannins, colour, hardness and intensity of sensory properties (flavour, colour, bitterness) – were determined as quality indicators. The results showed large variability in the physical and chemical parameters between the marmalades of different rowanberry cultivars and hybrids. The sensory evaluation of marmalades from rowanberry cultivars ‘Moravica’, ‘Mitchurinskaya krasnaya’, ‘Sorbinka’ and hybrid of rowanberry × hawthorn ‘Granatnaya’ showed that the degree of liking was from “neither like nor dislike” to “like moderately”, and marmalades from wild rowanberry, S. aucuparia var. sibirica and hybrid of rowanberry × pear ‘Alaya Krupnaya’ – from “dislike moderately” to “dislike slightly”.

One of the causes of cardiovascular diseases and overweight problem is a high consumption of sweets. Sugar is traditional food sweet matter. A change of sugar may therefore both change the perception of texture of products. The aim of the research was to evaluate properties of agar-agar jellies prepared with Jerusalem artichoke (Helianthus tuberosus L.) syrup (JAS). Soluble dry matter of experimental samples was determined by Mettler Toledo Refracto, separated sugars - by liquid chromatography, and acidity of jellies - by titration with 0.1 M NaOH. The measurements of pH were made by pH-meter Jenway 3510. Determination of vitamins B1 and B2 was made by the AOAC Official Method 986.27 and 970.65. Texture of samples was determined by using a Texture Analyser (Model TA.XT Plus; Stable Micro Systems), by cylindrical probe (P/25). Colour of jellies was evaluated by using Colour Tec-PCM. The results showed that soluble dry matter decreased from 64.5˚ Brix to 57.5˚ Brix, sucrose decreased by 6%, the acidity increased from 7.2 to 17.8˚, and pH values ranged between 3.8 and 4.5. The hardness of the samples decreased from 50.66N to 40.05N by increasing of added JAS concentration. Adding JAS in jelly, the content of vitamins B1 and B2 increased. Lightness “L” fluctuated between 24.26 and 14.60 with increase JAS concentration. The research suggests that different percents of Jerusalem artichoke syrup could be used as sugar substitute. The product becomes healthier, but the gels obtain a darker colour. Therefore it is recommended to look for other version to improve the colour of experimental jellies.

The quality and nutritional value of milk and dairy products are considerably influenced by the stability of its constituents. The aim of the present study was to evaluate the possibility of enhancing oxidative stability of cow’s milk fat and vitamin B2 using carrots and palm oil feed supplement CAF 100 as sources of natural antioxidants in cow feed. Milk samples were collected after 25-day period of feed supplementation. The intensity of riboflavin losses during its photo oxidative degradation in sunlight was measured by the fluorometric method. A slight and significant (p is less than 0.05) difference in higher vitamin B2 stability was seen in carrot-supplemented group (TG1) milk, where the losses of vitamin B2 were by 3.01% less compared to CG (CG). The oxidative stability of butter oil samples stored in 60 °C temperature was analyzed by peroxide value (PV) method. The oxidative stability of samples initially affected by light from both trial groups was significantly (p is less than 0.05) higher compared to CG showing the good potential of the cow diet enrichment with carotenoid additives. The longest induction period (larger than 14 days) was observed in CAF-100- supplemented (TG2) cow milk fats, which can be explained by carotenoids and tocopherol presence and its possible synergism in fat protection. The induction periods of the TG1 and CG were 12.03 and 10.97 days, respectively.

The aim of study was to investigate porcine circovirus-2 (PCV2) impact on the morphological sight of pig lymph nodes. The research was carried out in 2010. Three Latvian farms were investigated (from Latgale and Kurzeme) and thirty 5-15 weeks old pigs with clinical signs of Postweanig Multisystemic Wasting Syndrome were selected and observed. Four lymph nodes from each animal for histological and immunohistochemical investigations were taken. Thirty structural parameters of a lymph node were detected on histological slides: visualization of follicle structure, lymphocyte depletion and amount of histiocytic cell infiltration. As a result, changes in lymph nodes with PCV2 antigen were detected in all these structural parameters: increasing amount of PCV2 antigen in pig lymph nodes, but the greatest changes were in the follicles structure in lymph node. The increased amount of PCV2 antigen in lymph node; significantly decreases the amount of lymphocytes and increases the amount of histiocytes in them. Porcine circoviruss-2 in lymph node basically distributes from the lymph node cortex into the medulla, as well the amount of PCV2 antigen in lymph node also increased.

In order to perceive the pressure oscillation in the hydraulic hitch-system of the tractor and oscillation of the whole tractor aggregate at different loads on the hitch-system, a physical model is used. Changing the position of weight on physical implement boom, different moments of inertia were obtained and the appropriate load on the hydraulic hitch-system hydro cylinder. Results of driving experiments on the artificial roughness road present the maximum pressure peak of 220 bar in the tractor hydraulic system when weight was placed on further position, and the driving speed was 8 km hE-1 and tyre pressure was 1.2 bar. At the driving speed of 11.2 km hE-1 and with the same tyre pressure, the hydraulic system pressures reached up to 212 bar. On the weight on the middle position of boom, pressure in the hydraulic hitch-system reached 172 bar at the driving speed of 7.8 km hE-1 and tyre pressure of 1.2 bar, but at the driving speed of 11.2 km hE-1 and at the same tyre pressure, the hydraulic system pressures reached 165 bar. If the weight was placed on nearest position, pressure in the hydraulic hitch-system reached only 85 bar at the driving speed of 7.8 km hE-1 and tyre pressure - 1.2 bar, but at the driving speed of 11.2 km hE-1 and at the same tyre pressure, it was 98 bar. The investigation of the physical tractor-implement model allows the determination of the conformity of the physical model with real harrow implement.

Heterobasidion spp. is an important pathogen in the Northern Hemisphere, causing root and butt rot mainly in conifers. Norway spruce (Picea abies (L.) Karst.) is one of the most common tree species infected by Heterobasidion spp. In Latvia, 22.9% of Norway spruce stumps are infected. Heterobasidion spp. decreases timber quality, but what impact it has on Norway spruce growing in understory of dominant stand is not known. The aim of the study was to evaluate incidence of Heterobasidion spp. on understory Norway spruce in Myrtillosa forest type and impact on radial growth of trees. In autumn of the year 2011 in a sample plot located in forests of Kalsnava district a total number of 258 trees were examined for presence of Heterobasidion spp. Results showed that 54% of examined trees were rotted. In 30% of trees Heterobasidion spp. was detected. It is concluded that Heterobasidion spp. does not impact radial growth on understory Norway spruce trees.

In the 30ies of the 20th century stump extraction was identified as one of the most prospective technologies of forest sector to secure deliveries of solid biofuel. Now we are returning to the same challenges having the same targets – to secure energy independence and competitiveness of forest sector. MCR 500 is the prototype of combined stump extraction and mounding bucket for caterpillar excavator produced in Latvia by the LSFRI Silava and engineering company Orvi SIA. The device is made for extraction of stumps with diameter up to 50 cm. Additional benefit of the device is its ability to prepare soil for the forest regeneration by making mounds. The article summarizes results of productivity trials of stump extraction using the MCR 500 head and following forwarding of the material. Data from earlier studies are used to characterize comminution and road transport of stumps and chips. In total 3.5 ha were extracted during the studies. A harvested amount of stumps was estimated using biomass equations. It will be updated in further comminution studies. Average stock of extractable biomass (stumps and coarse roots) on the experimental sites was 28 tons ha-1. Productivity of stump extraction was 2.4...3.4 tons per efficient hour. Consumption of efficient time for scarification of soil was 3.4...4.3 hours per ha. Forwarding took 30 min per load (2.6 tons per efficient working hour). Prime cost of chips according to biomass equations is 9.78 Ls LV mE-3, according to expert judgement based harvested stock is 6.38 Ls LV mE-3.

The added value of woodworks is determined by the surface quality because it is the first one seen and evaluated by the client. In the production process it is quite problematic to evaluate woodworks surface quality because of large production capacity, and the processed material can be instrumentally tested with a definite time shift. In production most frequently the surface quality is evaluated visually, which is not quite precise. At the same time during the mechanical processing of wood noise is caused by cutting tools as they gradually wear out. The same reasons influence the increase of noise and the quality of woodwork surface. The essence of the problem is to analyze the registered increase of the noise level at a definite workplace and simultaneously follow the surface quality of the processed material – roughness and wear-out of the cutting instrument. The objective of the paper is to research the method of the noise level data collecting and application in order to evaluate wooden product surface quality during wood processing by milling machines. It would provide an opportunity to update the management processes of massive woodworks, supervise the surface quality of woodworks, reduce costs and increase the added value.