Sour cherries become more popular due to their food value. Therefore sour cherries could be a profitable crop for fruit growers in Latvia. Information about sour cherry response to soil moisture adjustment is needed, because based on previous studies it is not possible to predict the influence of irrigation and mulch on sour cherry growing. The trial was carried out at the Latvia State Institute of Fruit Growing in 2007 to determine the effect of soil moisture adjustment on the growth of different sour cherry cultivars. Woodchip mulch and drip irrigation were used as main factors, cultivars 'Bulatnikovskaya', 'Desertnaya Morozovoi', 'Latvijas Zemais', 'Orlica', 'Shokoladnica', 'Tamaris', 'Zentenes' were used as a secondary factor. Vegetative growth, branching angles of lateral shoots, proportions of pruned shoots, spurs and twigs were determined to characterize the response of cultivars to mulching and irrigation. In general use of drip irrigation increased vegetative growth of sour cherries, but the use of woodchip mulch decreased this growth. Branching angles were wider in variant with woodchip mulch. Cultivar 'Zentenes' most positively responded to use of woodchip mulch and drip irrigation.

The objective of the research was the shelf life extension of a salad with meat in mayonnaise. The microbial stability of the salad with meat in mayonnaise packaged under vacuum, in modified atmosphere, and using 'Sous vide' technology was examined and compared with conventionally packaged (in ambient air) salad. The salads were packaged in polyamide/polyethylene pouches with barrier properties as well as in pouches made from biodegradable plasticized poly-β-hydroxybutyrate or polylactic acid film. Control samples without preservatives were packed in traditional polypropylene containers covered with non-hermetic lids. PURASA L Powder Opti Form (sodium lactate) in the amount 5 g kgE-1, 10 g kgE-1, and 15 g kgE-1, and ethyl alcohol in the amount of 2 ml were used as single preservatives for separate samples. The studies of the samples were carried out after 1, 3, 7, 10, 15, 18, 25, 29, 42, and 52 storage days at the temperature of +4+-0.5 deg C. Experimentally the quality of the salad with meat in mayonnaise was characterized by measuring the total plate count of microorganisms. The obtained results indicate that different packaging technologies and addition of preservatives show significantly different influence on the microbial growth in different samples. 'Sous vide' packaging technology was effective for the shelf life extending and guarantee of safety of the salads with meat in mayonnaise.

In the study the growth and stem quality characters of geographically different Latvian Scots pine (Pinus sylvestris L.) populations were evaluated. In various regions of Latvia proportionally to the distribution of Scots pine 21 sample plot was established in 85 to 95 years old pure stands in forest type Myrtillosa growing conditions. In every sample plot 100 trees were evaluated estimating height of the tree, diameter at breast height, stem volume, length and quality of the branch-free stem section, relative branch thickness, branch angle and stem straightness. Pine populations were compared in different seed zones (Western and Eastern), as well as in various regions (Western, Central, South-eastern, North-eastern). In order to describe the geographical differences of populations with help of growth features, tree height was chosen because the relation between height and stem quality features is positive. The populations of the Eastern seed zone substantially overcome the populations of the Western seed zone both in terms of growth features, as well as in stem quality. Substantial are also differences between populations growing in various regions in terms of average height, length and quality of branch-free stem section, relative branch thickness and branch angle, but not stem straightness. Western populations present the lowest growth feature values and stem quality. The height and stem quality features of the North-eastern populations considerably exceeded the features of other regions' populations.

Large proportion of 30-50 years old spruce stands originated from overstocked plantations can be characterized by low growth potential and present serious problem to forest managers. Although according to legislation unproductive spruce stands can now be clearcut, possible alternative solution allowing a forest owner to remove only trees with the worst growth potential would be also welcome. To be able to recommend any silvicultural measures, information on the inner structural development of the stands is necessary. The aim of this study was to analyze temporal structure of several spruce stands that have originated from overstocked plantations and now belong to the 2nd (increased risk stands) or 3rd (unpromising stands) growth potential groups. Data for the study from seven sample plots located in Forest Research Station ''Kalsnava'' and thinned with different intensity were used. Tree diameter distribution, volume accumulation patterns and tree mortality were analyzed. Correlation between tree diameter and tree diameter difference in the observation period from 2000 to 2006 was weaker than in the observation period from 2006 to 2009, indicating further decline of growth potential. In most cases the major part of the volume was accumulated in the middle of the diameter class distribution. For most of the trees one or both sawlogs were of good or average quality. In order to develop optimal and profitable stand management model, the effect of different thinning methods in spruce stands of low growth potential should be studied in the future.

Both forestry theory and practice have proved that amelioration favours the growth of forest stands significantly. The growing stock increases even 10 times, if the amelioration system is well-functioning. Joint Stock Company Latvia State Forests that is managing half of forests in Latvia has started renovation of old amelioration systems aiming to improve the productivity of state owned forests in Latvia. In order to evaluate the impact of the renovation of the old amelioration systems, a tree ring width in 7 pine stands, 5 spruce stands and 3 birch stands was analysed. This study shows that the renovation itself has not affected the productivity of mature pine, spruce and birch significantly 3-4 years after the renovation. Authors have come to a conclusion that the reason for that could be too short observation period or particularities of a stand structure and age.

Climatic changes are shifting the potential tree distribution limits of many tree species northwards. One of such species is Fagus sylvatica, currently represented in Latvia only by a few stands. In order to increase knowledge on its potential use in the forest management, the aim of our study was to characterize the growth of beech in a young stand in the central part of Latvia. The stand of beech and spruce, mixed in rows with an initial spacing of 2.5 x 2.5 m in Oxalidosa forest type was assessed. Survival of European beech in clear cutting was similar to that observed for the native Norway spruce (73% and 79%, respectively), but both height and diameter were notably and significantly superior for wildlings at the mean age of 15 ± 2 years, reaching on average 7.4 ± 0.30 m and 8.9 ± 0.69 cm, respectively. Increasing ring width with increasing tree age for both tree species was observed until the last four years, when large and increasing superiority of beech over spruce, coinciding with reduction of ring width of spruce, was noted. It was most likely caused by intensified competition due to very wide crowns formed by young beech trees in the plantation with wide spacing: average crown radius reached 2.4 ± 0.16 m, for few trees exceeding even 4 m.

The impact of climatic and genetic factors on needle cast damage, as well as relationship between the degree of damage and survival and growth of trees was evaluated in the study. The analysis was done in two series of experiments, both established in two locations in Latvia (central and eastern part). Needle cast damage (in 5 grade scale) as well as the height and height increment, diameter of root collar and survival of trees were assessed. Results suggest that the degree of needle cast damage was influenced by the genetic, as well as climatic factors, and also their interaction. The average degree of needle cast damage in experiment of open-pollinated families was 4.7 ± 0.01 in central and 4.6 ± 0.03 in eastern Latvia; in the experiment of control-crossed families it was 4.6 ± 0.02 in central and 3.4 ± 0.04 in eastern Latvia. The impact of genetics on the needle cast damage degree was statistically significant (p is less than 0.05), and this effect was observed when any of growth traits (diameter, height or height increment) was used as a covariate in analysis. Results suggest the potential to select more resistant families, since the genetic correlation of grade of the damage between locations was significant (r = 0.40 - 0.72) and therefore improve also the growth of trees, since the grade of the damage had a negative correlation with growth traits both at provenance and family mean level (r = -0.69 and r = -0.42; p is less than 0.01).

Wood based ash can be used as a liming material and fertilizer in forest, thus providing a solution for utilization of wood ash and formation of additional increment of trees, especially on organic soils, where lack of potassium and phosphorus is a well-known factor limiting the growth of trees. Yet, many studies have been made with adverse results mostly because of different soil types and species investigated. However, by now the best results on fertilization with wood ash have been found on drained peatlands, where some nutrient deficiencies have emerged. The aim of this study was to find out the growth response of Norway spruce on drained organic soils after spreading of potassium sulphate (K2SO4) and wood ash (WA). The experiment was carried out in three middle aged Norway spruce (Picea abies) stands on drained mineral and peat soil. Experiment consisted of three replications of each treatment in each stand including WA, K2SO4 and the control on 400 square meter sub-sample plots each. The diameter and height of trees were measured. The samples of increment cores were collected 4 years after fertilization to determine the additional volume increment, which varied from 8.5 m**3 haE-1 in WA plots and from 9.7 m**3 ha-1 to 17.2 m**3 haE-1 on K2SO4 plots. Both - the wood ash and potassium application - significantly increased the increment of Norway spruce on drained mineral and peat soil, although no significant differences were found between the treatments (p = 0.82, α = 0.05).

Prolonged summer drought periods are forecasted for the Baltic Sea region during the 21st century, thus increasing the risk of drought stress of saplings used in forest regeneration. Nevertheless, the vitality of young stands might be increased by the selection of suitable planting material. The aim of this study was to estimate the effect of changes in distribution of summer precipitation on height increment, biomass distribution and root morphology of Scots pine and silver birch planting material commonly used in the forest regeneration in Latvia. Containerized pine and bare rooted birch saplings, planted in three different soil types, were subjected to altered distribution of summer precipitation, provided by the use of automated shelter. Sheltered saplings were weekly irrigated with the sum of precipitation of a corresponding period, while afield planted saplings had an unchanged precipitation regime and served as control. Height increment was measured once per week and estimation of morphology of saplings was done after the end of every vegetation season. Significant (p is less than 0.05) differences in height increment, and shoot and root biomass were observed among the same planting material in different irrigation regimes and soil types. In the control plots of peat soil, pine had a significantly (p is less than 0.05) larger height increment while birch-significantly (p is less than 0.05) smaller compared to experiment. Forecasted longer drought periods might reduce the growth of Scots pine in fertile forest types but silver birch growth might be affected in fertile mineral soils in future.

Assortment improvement is a natural process of updating varieties and improving the quality of variety assortment. The article presents the results of studying the introduced grape (Vitis vinifera) varieties in the conditions of the southeast of Kazakhstan, in particular in the bottom-mountain area of Almaty region. The beginning and the end of the main phenological phases passing for the vegetative period in a grape plant directly depended on climatic and weather conditions of this district. It is established that varieties ‘Kuibyshevsk early-maturing’, ‘Iyulsky’ and ‘Priusadebny’ have a good degree of eyes wintering buds and are able to give a yield of high quality in this area in comparison with recognized variety ‘Almaty early-maturing’.