Solvita Zeipiņa

By applying a word co-occurrence analysis, this article aims to identify key research directions in rooftop agriculture and review the most frequently discussed benefits and challenges. A total of 216 articles from the Scopus database were included. The review is conducted at three consecutive levels—co-word network analysis and thematic cluster detection, thematic grouping based on commonly used keyword pairs, and a manual review of articles. Results reflect the high interdisciplinarity of rooftop agriculture as a research field, with several main thematic directions emerging, including food provision, cultivation practices, circular economy, sustainable urban development, and regulating and supporting ecosystem services. Meanwhile, climate change and sustainability were identified as the key contextual factors, motivating the overall research on rooftop agriculture. Results indicate underdeveloped thematic directions of social and economic aspects, while political aspects are scarcely represented. Future research should adopt a more systemic approach that considers rooftop agriculture as a complex system comprising interacting environmental, technological, economic, social, and institutional components, as well as a diverse network of actors.

Urban horticulture has become an increasingly vital part of sustainable food production systems, offering ways to improve food security, cut down on food transport distances, and foster environment...

Optimizing nutrient uptake efficiency (NUE) through an understanding of system-level dynamics and crop-specific physiological thresholds is essential for the resilience of North European vegetable production under shifting climatic conditions. This study evaluated the uptake and efficiency of macro- and secondary nutrients (N, P, K, Ca, Mg) in cabbage, carrot, red beet, and onion over a five-year period (2021–2025) in Latvia, comparing organic and integrated management systems. It was hypothesized that NUE on commercial farms is currently suboptimal due to standardized bulk applications and that systems integrating sustainable practices would demonstrate higher nutrient uptake efficiency than those relying exclusively on mineral fertilization. The results revealed a notable yield–input divergence, where increased fertilization rates failed to provide proportional yield gains, as evidenced by the lack of a strong linear relationship (R² < 0.07) and variable correlation coefficients (e.g., r = 0.52 for N in cabbage and r = −0.47 for Ca in carrot). These findings suggest that abiotic stressors and technical constraints may outweigh the influence of nutrient volume alone. This divergence was less pronounced in organic farming systems compared to integrated ones and varied notably by crop. Such species-specific responses indicate a complex role for mineral nutrition in root crops that requires further physiological investigation. No consistent differences in nutrient concentrations were observed between farming systems, indicating that inter-annual climatic variability is the dominant driver of nutrient dynamics. Furthermore, the integration of green manures and supplemental irrigation triggered extreme apparent system-level N-NUE values (exceeding 500% in some cases), reflecting the successful mineralization of legacy nitrogen and enhanced mass flow to the root zone. The study concludes that current fertilization methodologies in the Baltic region may lead to over-application. To ensure climate-resilient horticulture, management strategies must transition toward balancing ionic ratios (Ca:K) and synchronizing inputs with specific crop removal rates, rather than relying on standardized bulk applications.

Strawberry is one of the most important berry crop grown around the world and their consumption increases every year. The introduction of new practices promoting farm sustainability and long-term soil health in strawberry production systems is very essential. Towards environment- and climate-friendly farming practices intercropping can be used to improve soil microbiological activity and biodiversity, and reduce the use of pesticides and mineral fertilizers, while the right choice of intercropped plants is of great importance to achieve these goals. The trials on strawberry intercropping were established in Latvia in 2021. Three treatments with different intercropping plant rotations, including crimson clover, pea, garlic, marigold, and winter rye mix with vetch, were compared to conventional strawberry growing using straw mulch. Trial was installed in three locations: two organic farms and the Institute of Horticulture (LatHort). Thus representing climatically different regions and different soil conditions. Strawberries were grown in 1.2 m distant rows, where in the intercropping treatments, each second interrow was occupied by companion plants. Soil microbial activity was evaluated during vegetation seasons by determining soil respiration rate (SRR) and dehydrogenase activity (DHA) several times per season in 2021 and 2022. Strawberry vegetative development was evaluated at the end of each vegetation season. During the investigation period, soil microbial activity fluctuated during vegetation seasons, depending on growing conditions. In 2021, SRR varied from 1.9 – 3.3 CO2 mg L- 1, while in 2022, from 2.1 - 3.4 CO2 mg L-1. DHA varied from 46 – 134 INTF, µL×????−1 × h in 2021 and 60 – 101 INTF, µL×????−1 × h in 2022. Intercropping had low influence on microbial activity and results differed within each location. Strawberry plant biomass differed among locations and treatments with the highest above-ground biomass observed in LatHort during second growing season in conventional growing system (790 g plant-1).

The interest in cultivation of vegetable soybeans, also known as edamame, in the North Europe region has increased during the last years due to their high nutritional value and excellent taste properties. During the last decade the possible growing area for soybeans has expanded towards the north due to changes in climate as well as breeding efforts. In order to adopt vegetable soybean growing technology for commercial cultivation in the North Europe region, independent experiments were carried out in Latvia and Norway. This study shows that vegetable soybean is a crop with potential for successful cultivation at higher latitudes, such as the Nordic–Baltic region in North Europe, with yield levels comparable to other regions of the world. We observed that hydrothermal conditions had the most significant impact on soybean plant development. Sowing or planting as early as possible is a key to obtaining sufficient yield levels. In the study, the vegetation period needed to be at least 123 to 127 days, with growing degree days (GDD) at least 650, and hydrothermal coefficient (HTC) above 1. Under such conditions, the obtained marketable yield in Latvia ranged between 3 to 10 t ha⁻¹ during the period of 2017–2019, and 1.2 to 10.5 t ha⁻¹ in Norway. Planting density of 20–25 plants per m² appeared to be optimal. The variety ‘Midori Giant’ showed the most stable yield outcome, but ‘Chiba Green’ also gave a satisfactory yield.

Fava bean (Vicia faba L.) yields are featured by high variability, influenced by the agro-environmental conditions during the growing seasons. These legume crops are sensitive to hydric and heat stresses. The adaptation depends on the efficiency of specific cultivars to use the available resources to produce biomass. This capacity is determined by the genotype and agronomical management practices. The present work aimed to uncover the influence of Baltic agro-environmental conditions (fava bean cultivar, plant density, climate, and soil features) on yield and protein content. For this, field trials were set under Baltic agro-climatic conditions, in Latvia and Estonia with five commercially available fava bean cultivars, representing broad genetic variation (‘Gloria’, ‘Julia’, ‘Jogeva’, ‘Lielplatones’, and ‘Bauska’). The results evidenced ‘Bauska’, ‘Julia’, and ‘Lielplatones’, as the most productive cultivars in terms of seed yield (4.5, 3.7, and 4.6 t ha⁻¹, respectively) and protein yield (1.39, 1.22, and 1.36 t ha⁻¹, respectively) under Estonian and Latvian agro-climatic conditions. Sowing these specific cultivars at densities of 30–40 seeds m⁻² constitutes sustainable management for fava bean production in conventional cropping systems in the Baltic region.

Zeipiņa S. (2021) Influence of agroecological factors on the yield and quality of rarely-grown vegetables. The Doctoral Thesis. Latvia University of Life Sciences and Technologies. Jelgava, LLU 130 p. The research was carried out from 2013 to 2019 in the Institute of Horticulture (LatHort). The aim: to evaluate the influence of agroecological factors on the rarely-grown vegetables yield and quality on three morphological different species: stinging nettle (Urtica dioica L.), globe artichoke (Cynara cardunculus L. var. scolymus) and vegetable soybean (Glycine max L.). The tasks of the research: • to evaluate the growth and development of stinging nettle, globe artichoke and vegetable soybean under various agrotechnical factors and meteorological conditions; • to evaluate the influence of various agrotechnical factors and meteorological conditions on the yield of selected vegetables; • to determine and evaluate the nutritional value changes under various agrotechnical factors and meteorological conditions. Work novelty: for the first time in Latvia the investigations on the influence of agroecogical factors on stinging nettle, globe artichoke and vegetable soybean are performed. All these vegetables have high potential for the healthy human diet. Work hypothesis: ensuring suitable agrotechnical factors and reducing effect of meteorological conditions can increase studied vegetables yield and the content of biologically active compounds. Scientific actuality of work: obtained results are important and useful for commercial vegetable producers, the research gives insight in the yield formation and crop quality changes under various agrotechnical factors and meteorological conditions. The structure of the Thesis: introduction, literature review, materials and methods of the research, results and discussion, conclusions, references and appendix. Introduction. Topicality of the work is justiefied, research goal and tasks are formulated, research novelty and hypothesis are estimated. The list of author`s scientific publications on the topic of Thesis is provided. A literature review is arranged into 10 sub-chapters, where the main biological active compounds in investigated vegetables are described, as well as influence of agroecological factors on their content, the growth, development, and yield formating of vegetables is studied. Also, the biology, economic importance, nutritional value, growing conditions, and influence of agroecological factor on the growth, development, yield and content of biologicaly active compounds is described for selected vegetables. Materials and methods of the research are arranged into 5 sub-chapters, wehere the methodology of the research, meteorological conditions, measurements, methods of biochemical analyses and statistics are described. Results and discussion are arranged into 8 sub-chapters, where yield and changes of biologically active compounds are analysed for stinging nettle, globe artichoke and vegetable soybean under influence of various agroecological factors. Conclusions give answers on the tasks highlighted for promotion thesis. References consist on bibliographic description of the sources of information used. Appendix describe research materials and results. Work contains of 68 figures, 10 tables, 4 annexes and 268 bibliography items.

BACKGROUND Monoculture is used mostly in conventional agriculture, where a single crop is cultivated on the same land for a period of at least 12 months. In an organic and integrated growing approach, more attention is paid to plant–environment interactions and, as a result, diverse growing systems applying intercropping, catch crops, and green manure are being implemented. Thus, field experiments for evaluation of vegetable/faba bean full intercropping efficiency, in terms of vegetable and faba bean yield and protein content, were set up during two consecutive growing seasons (2014 and 2015). RESULTS Data obtained showed that the most efficient intercropping variants were cabbage/faba bean (cabbage yield 1.27–2.91 kg m⁻², immature faba bean pods 0.20–0.43 kg m⁻²) and carrot/faba bean (carrot yield 1.67–2.28 kg m⁻², immature faba bean pods 0.10–0.52 kg m⁻²), whilst onion and faba bean intercrop is not recommended for vegetable growing since it induces a very low onion yield (0.66–1.09 kg m⁻²), although the highest immature faba bean pod yield was found in the onion/faba bean intercropping scheme (up to 0.56 kg m⁻²). CONCLUSION Vegetable/faba bean intercropping can be used in practical horticulture for carrot and cabbage growing in order to ensure sustainable farming and environmentally friendly horticultural production. © 2017 Society of Chemical Industry

Different vegetables are a good source of essential components for human food. Consumers are more and more aware of a healthy and balanced diet. Vegetables usually contain natural antioxidants which neutralize free radicals in the human body. The composition of biologically active compounds in plants is depending on the climate and growing conditions, cultivar properties, plant development stage, harvesting time, and other factors. The aim of the research was to evaluate the fluctuation of antioxidant activity in leaves of four common nettle (Urtica dioca L.) clones and three garden orache (Atriplex hortensis L.) varieties during vegetation period in Latvian conditions. Experiments were carried out in open field conditions in the Pūre Horticultural Research Centre during the vegetation period of 2014, in two soil fertility variants for nettle and two sowing periods for garden orache. Antiradical activity was determined using the 2.2-diphenyl-1-picrylhydrazyl radical (DPPH*) method. In nettle leaves, antioxidant activity ranged between 17.31–80.77 %, depending on soil fertility, nettle clone and plant age, and in orache leaves between 17.9–54.0 % depending on variety and sowing time. In nettle leaves, the antioxidant activity at the beginning of the vegetation period ranged between 31.0–62.7 %, the highest activity was observed at the stem elongation stage (75.5–78.5 %). A higher antiradical activity was detected in the control variant (without compost treatment) at the 3–5 and 7–9 leaves stage. In other development stages, better results were obtained in the fertilized variant where compost and peat were used as an organic manure. Differences were found also among clones, especially in the 3–5 leave stage. Significant differences for garden orache leaves were found between sowing times. In the first growing period the antiradical activity ranged between 46.1–54.0 %, in the second it was two times less.DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12055