Fire has been a part of natural disturbance regime in boreal and to some extent also hemiboreal forests, affecting soil and light conditions, seedbanks, trees and ground vegetation. The most significant factors affecting occurrence, severity and size of forest fires are anthropogenic, weather and the environment, all of which are changing due to human-caused climate change. This paper discusses medium term (25 years) vegetation development in five different biotopes after fire disturbance. Sample plots were established in Slitere Reserve (now National park) in north-western Latvia on areas affected by large fire in 1992. Data were collected in 1993, 2002 and 2017. The aim of the study was to characterize the regeneration and succession of ground vegetation after the fire. In 1993, species such as bog-rosemary (C) were observed in the ground vegetation a year after the fire. In 2002 liverworts appeared, indicating that the bog has acquired more stable and wetter conditions, but in 2017, liverwort mosses were no longer present and the percentage cover of Rubus chamaemorus decreased significantly and Calluna vulgaris, sphagnum sp., and Betula pendula were present in large quantities in the bog. Comparing these studied years, it can be concluded that all these years the biotopes and species have continuously developed and are regenerating.

Latvia University of Life Sciences and Technologies and Organizing Committee of Annual 26th International Scientific Conference on Research for Rural Development 2020 tried to continues a tradition of bringing together researchers, academic and professionals in Jelgava, from 13 to 15 May, 2020 from all over the world. But, unfortunately, this year the rules were set by the coronavirus disease (COVID-19) pandemic. We did start new tradition from 2020, account from 1st until the 26th conference and totally are 35 volumes. The interdisciplinary papers contributed the most recent scientific knowledge in agricultural sciences, forestry and wood processing, food sciences, veterinary medicine, economics, rural and environmental engineering, water management; information and communication technologies and education. These Proceedings will furnish the scientists of the world with an excellent reference volume. We trust also that this will be an impetus to stimulate further study and research in all these areas.

The Annual 24th International Scientific Conference ‘Research for Rural Development 2018’ was special and dedicated to the Latvia a 100 years since became an independent state, 155th Anniversary of Latvia University of Life Sciences and Technologies (LLU) and 280th Anniversary of Jelgava palace, where is located the main building of university. In the retrospect of four months later, we can count the Conference as a great success as interdisciplinary studies. The theme – Research for Rural Development - attracted participation more than 167 researchers with very different backgrounds. There were 139 presentations from different universities of Estonia, Poland, Kazakhstan, Lithuania, Ukraine, Sweden, South Africa, Indonesia, Russia and Latvia. The interdisciplinary proceedings of the Annual 24th International Scientific Conference ‘Research for Rural Development 2018’ (two volumes since 2010) are intended for academics, students and professionals. The subjects covered by those issues are crop production, animal breeding, agricultural engineering, agrarian and regional economics, food sciences, veterinary medicine, forestry, wood processing, water management, environmental engineering, landscape architecture, information and communication technologies.

The four independent reviewers estimated each paper and recommended 81 articles for publishing at the proceedings consisted of 2 volumes, which started life as presentations at the Annual 23rd International Scientific Conference “Research for Rural Development 2017” held at the Latvia University of Agriculture, in Jelgava, on 17 to 19 May 2017. In the retrospect of four months later, we can count the Conference as a great success. The theme – Research for Rural Development - attracted participation more than 155 researchers with very different backgrounds. There were 124 presentations from different universities of Poland, Kazakhstan, France, Czech Republic, Lithuania, Estonia, India, Russia and Latvia. Thank you for your participation! We are sure that you have learned from the presentations and discussions during the conference and you can use the outcomes in the future. The cross disciplinary proceedings of the Annual 23rd International Scientific Conference “Research for Rural Development 2017” (two volumes since 2010) are intended for academics, students and professionals. The subjects covered by those issues are crop production, animal breeding, agricultural engineering, agrarian and regional economics, food sciences, veterinary medicine, forestry, wood processing, water management, environmental engineering, landscape architecture, information and communication technologies. The papers are grouped according to the sessions in which they have been presented.

Modern varieties developed under conventional plant breeding programs do not always perform well under organic and low-input growing conditions. Therefore, organic farmers need varieties adapted to variable environmental conditions. This means emphasis on traits such as nutrient uptake and use efficiency, good weed suppression ability and disease resistance and can be achieved via extended genetic diversity within the varieties: variety mixtures and populations of self-pollinating crops. The aim of the present study was to review published scientific literature about importance and research results on this topic. Scientific articles about the necessity of such studies and results of investigations performed in different countries have been studied. The main results show that variety mixtures have advantages in terms of disease control and yield stabilization and performance of mixtures may be affected by various factors – choice of components and its number, interactions between plants of components, manner of the mixing and growing technology. Depending on parental material, populations contain greater genetic diversity than variety mixtures. There are trends observed in the studies that yield of populations increased over generations and they are more stable than modern varieties, but there is no evidence that they would be significantly more productive. This research direction has recently become topical and is not sufficiently widely covered in the world agricultural science. The obtained results are inconsistent.

Flax (Linum usitatissimum L.) fibre and seeds are widely used to produce healthy and environmentally friendly products. It is known that the main factors that influence flax fibre’ and seeds’ yield are genotype and growing conditions. The main task of the Latvian flax breeding program is to develop flax genotypes that are highly productive (both fibre and seeds) and well adaptable to changing environmental conditions. Goal of this study is to identify high yielding genotypes with good adaptation to local variable agro-ecological conditions. The agronomically important traits, such as yield of stem and seeds, total and technical plant height and fibre content were evaluated for 13 Latvian origin flax lines and standard variety ‘Vega 2’. The field trials have been carried out over the period from 2012 to 2015 at the Agricultural Scientific Centre of Latgale. The regression, correlation, coefficient of variation and cluster analysis between yield and yield provided components were used for identification of high yielding genotypes with good adaptation. On the basis of cluster analysis the genotypes were classified in two groups by lower and higher yield of stem, fibre content, total plant height and technical plant height. The line ‘I18-1’ was identifying as genotype with the highest average yield of stem (751.25 g mE-2) as well as highest yield against other genotypes in moisture and drought years. Most valuable by the average technical plant height was line ‘L26-1’ (73.05 cm).

Since the middle of the last century rapid intensification of agricultural production systems has resulted in dramatic increase in fertilizer consumption as fertilizer has been considered as one of the most important factors for increased yields. However, not all the nutrient ions in a fertilizer applied to soil are taken up by crops, thus certain amount of the applied fertilizer is lost from agricultural fields leading to increases in nitrogen surplus, nitrogen losses to the environment and harmful impacts on biodiversity, air and water quality. This study aims to focus on crop fertilisation planning which is based on the knowledge of physical and chemical properties of soil and involves performing soil tests, designing a fertilisation plan and its practical implementation as well as calculating the balance of N, and to evaluate crop fertilisation planning as a tool for achieving balanced economic and environmental benefits in crop farming, which play an important role in efficient farming. In this study, the authors have analysed current situation in Latvia regarding requirements for fertilization planning in crop farms and have assessed potential costs and benefits from fertilisation planning. The research finds out that total cost of introducing of fertilisation planning ranges from 34 to 22 EUR haE-1, however, fertilisation planning is a neutral measure where costs are compensated by savings from N inputs which ranges from 10 to 40 kg N haE-1.Fertilisation planning generates environmental benefits, i.e. – reduces direct N2 O emissions from agricultural soils by 47 – 187 kg CO2eq haE-1 through reduced N fertilizer inputs.

Artichokes (Cynara cardunculus L.) contain many minerals, vitamins, fibres, and polyphenols. Environmental conditions and climate change on a global scale affects the overall agriculture and food supply. Composition of biological active compounds in plants depends on the climate and growing conditions, cultivar properties, plant development stage, harvesting time and other factors. The aim of research was to evaluate the effect of agroecological factors on yield and flavonoids content of globe artichoke. An experiment was carried out under open field conditions in Institute of Horticulture, in Pūre investigation fields during the vegetation period of 2014 and 2015. The experiment was arranged in two different soils: brown soil with residual carbonates and the soil strongly altered by cultivation. The yield and its quality were analysed during the whole vegetation period. Higher yield was observed in the soil strongly altered by cultivation. The results showed tendency that the higher flavonoids content in artichoke heads was observed in 2014 than in 2015. Significant differences between flavonoid content per harvest time are observed in both soils.

Cow lifespan is one of most important economical traits in every dairy farm and is affected by different environmental factors. One of genetic factors that affect longevity is cow conformation traits, which varies within different breeds, farms and animals. The aim in this study was to determine how stature and linear conformation traits affect cow lifespan and lifetime milk productivity. In the study, data about 34806 crossbred Holstein Black and White and 38201 Red cow group breed cows, which ended at least one full lactation, and were culled from 2002 – 2012 year were analysed. Data about cow productivity and culling was obtained from Latvian Agricultural Data centre. In the study, data about cow stature, udder depth, central ligament, teat length, and rear and front teat placement were analysed. Conformation traits were distributed in 3 groups. The average lifespan of analysed cows was 1869.9 days in which average 18550.8 kg energy corrected milk (ECM) was obtained. Holstein Black and White cows characterize with shorter lifespan (1833.7 days) than red breed group cows, but lifetime productivity is for 2339.1 kg ECM higher than for average red breed cow. Significantly longer (p is less than 0.05) lifespan – 2031.6 days was in cow group with stature 100 – 135 cm, but in cow group with stature more than 146 cm there is significantly higher lifetime and life day productivity. There is a significant difference between lifetime milk productivity and rear and front teat placement. Significantly higher productivity was given by cows with teat placement inside of quarter (linear evaluation 6- 9 points).

The research was conducted in Latvia University of Agriculture Research and Study Farm ‘Vecauce’ in 600 dairy cows herd, in the period from 2009 to 2013. Within the framework of the research, growth indicators (from birth till the first delivery) of 102 dairy cow calves were analysed. Live weight and hip height of the heifers were found out at birth, at the age of 6 and 12 months, at first insemination and first calving. Heifers born to primiparous cows in both breed groups had notably lower live weight (42.0 and 42.4 kg), as compared to the 4th group heifers born to mature cows (p is less than 0.05). At the age of one year, the greatest weight among the red breed animals was recorded for the 4th group heifers born to mature cows (on average 354.8 ± 7.09 kg), while in Holstein breed those were heifers born to mothers calving on average for the 2nd time (on average 363.0 ± 6.47 kg). The 4th group heifers born to mature Holstein cows had notably greater hip height at birth – on average 78.1 ± 0.9 cm (p is less than 0.05). Heifers of red and Holstein breeds on average were inseminated at the age of 14.6 – 14.8 months as they reached live weight 395 – 396.5 kg. Heifers of red breeds on average calved at the age of 25.8 months, whereas Holstein heifers - of 26.4 months. The research aimed at analysing growth rates of heifers born to dairy cows at different age.