Armenian National Agrarian University

This paper investigates the existence and uniqueness of smooth solutions to the Cauchy problem for a class of nonlinear wave equations in 3D spaces. Under appropriate conditions on the nonlinearities such as concavity, monotonicity, and smoothness, an existence theorem is established, guaranteeing a smooth and bounded solution to the problem. Furthermore, uniform convergence of the corresponding successive approximations to the solution is demonstrated, with a convergence rate characterized by an exponentially decreasing geometric progression. A uniqueness theorem is also proven for solutions within a specified class of smooth and bounded functions. Specific examples of nonlinearities are presented to highlight the applicability and significance of the results obtained.

Background: Blackberry (Rubus spp.) is a valuable functional food crop rich in phenolics, anthocyanins, flavonoids, vitamin C, and other bioactive compounds. Although micropropagation enables rapid production of uniform planting material, its effects on multi-year field performance and fruit biochemical quality remain insufficiently documented under specific agroecological conditions. Objective: This study compared micropropagated (MP) and conventionally propagated (CP) plants of four thornless blackberry cultivars (‘Doyle’, ‘Loch Ness’, ‘Natchez’, and ‘Freedom’) under Armenian conditions, focusing on field performance, disease incidence, and fruit biochemical quality relevant to functional food applications. Methods: MP plants were produced through nodal explant culture, shoot multiplication, IBA-mediated rooting, and greenhouse acclimatization. Field trials were established in 2021 using a randomized complete block design. During 2022–2023, plant survival, growth, flowering, yield, fruit weight, and disease incidence were evaluated. Fruit quality was assessed for vitamin C, total phenolic content (TPC), anthocyanins, flavonoids, and DPPH antioxidant capacity. Results: MP plants generally showed higher survival, vegetative growth, flowering, yield, fruit weight, and lower disease incidence than CP plants. In 2023, MP ‘Loch Ness’ produced 17.4 stems plant⁻¹, while disease incidence was 7.5–11.3% in MP versus 18.1–26.5% in CP plants. MP fruits contained higher levels of bioactive compounds, with the highest values in ‘Natchez’: vitamin C, 31.4 mg/100 g FW; TPC, 412.7 mg GAE/100 g FW; anthocyanins, 159.2 mg C3G/100 g FW; and flavonoids, 62.1 mg CE/100 g FW. DPPH antioxidant capacity was approximately 32% higher in MP fruits across all cultivars. Conclusion: Micropropagation improved field performance, phytosanitary status, and fruit biochemical quality of the evaluated thornless blackberry cultivars. It therefore offers a promising strategy for standardized production of high-quality blackberry planting material and fruit with functional food potential. Novelty of the study։ This study provides a multi-season, cultivar-specific comparison of micropropagated and conventionally propagated thornless blackberry plants under identical open-field conditions in Armenia. By combining agronomic performance, disease incidence, and fruit biochemical traits, it evaluates how propagation method influences both field productivity and the accumulation of selected bioactive compounds. Keywords: Blackberry; Rubus spp.; Micropropagation; Bioactive compounds; Antioxidant activity; Functional food

Efficient soil management in vineyards with stony, loamy–sand soils is crucial for energy conservation and sustainable production, particularly in organic systems where herbicide use is restricted. Rotary tillers with vertical axes are widely used for intra-row and near-trunk tillage but are often limited by high energy demand. This study aimed to develop a mathematical model to optimize the operating regime of rotary tillers by evaluating the relationship between torque resistance, which is the key energy indicator, and primary kinematic parameters: disc rotational speed and diameter. Field experiments were conducted at the Voskehat Experimental Station in Armenia using a two-factor, second-order central composite design. Torque was measured with a high-precision strain-gauge system, and two groups of L-shaped blades (Z₁ = 3 and Z₂ = 4) were tested. Regression analysis showed that disc diameter had a strong linear effect on torque, while rotational speed exhibited a weaker influence that varied with blade number. In all cases, torque variation did not exceed 10 N·m within the speed range of 16.5–20.5 s-1. Distinct functional patterns of torque variation were observed depending on blade number, likely reflecting the interaction between soil deformation wave propagation and disc rotation. Defining the optimal operating regime, therefore, requires minimizing torque while ensuring that the kinematic parameters satisfy agrotechnical requirements, thereby preventing excessive soil pulverization, reducing erosion risk, and ensuring high-quality tillage.

Mountain agricultural systems face acute production constraints, requiring evidence-based land-use planning to support crop diversification and sustainable intensification. This study assessed land suitability for eight crops (apricot, peach, pear, wheat, potato, cabbage, broccoli, and green bean) in Armenia's mountainous regions using an integrated Analytic Hierarchy Process (AHP) and Geographic Information System (GIS) approach. Thirteen biophysical parameters, encompassing climate, topography, and soil properties, were evaluated using expertderived, crop-specific weights, with elevation thresholds applied as strict constraints. Results revealed pronounced differences in land-crop matching efficiency across land-use types. Perennial crops exhibit strong spatial constraints: only 4.1% (4482 ha) of cultivable land was classified as highly suitable (S1), while the combined suitable area (S1+S2) reached 20,574 ha. Low to moderate overall efficiency (16.9-51.1%) highlights their sensitivity to climatic and topographical conditions. Wheat suitability analysis identified 10,369 ha (S1+S2) with moderate efficiency (43.6-55.5%), supporting national self-sufficiency objectives. Potato demonstrated the highest suitability (6490 ha S1, 13,527 ha S1+S2), indicating strong agroecological compatibility and significant potential for market-oriented production. High-value vegetables revealed significant untapped potential: broccoli (13,133 ha S1+S2) and green beans (12,611 ha S1+S2), despite their currently limited cultivation. Overall, 43-60% of cultivable land (arable land, irrigated arable land, and backyards) falls within suboptimal suitability classes (S3-NS), indicating substantial potential to enhance agricultural production through targeted crop reallocation. Specifically, improving crop-land matching within existing arable land and prioritising the reuse of abandoned farmland for high-value crops such as broccoli and green bean can enhance productivity and farm income. A widespread deficiency of nitrogen and phosphorus indicates that improved soil fertility management is a prerequisite for successful diversification. These findings provide a robust scientific basis for climate-smart agricultural planning, including crop prioritisation, diversification into high-value crops, and improved land-use efficiency in mountainous regions.

This scientific study is devoted to assessing the sustainable development potential of the rural communities of Sis, Ranchpar, and Hovtashat in the Ararat Region through an integrated analysis of economic, social, and environmental components. Sustainable development is considered as a system that simultaneously ensures economic growth, improvement of living standards, social well-being, and the conservation of natural resources. The aim of the research is to analyze the main economic sectors operating in these communities: crop production, livestock farming, and aquaculture – evaluate their efficiency, and propose new integrated development approaches. The results of the study indicate that these three sectors are currently developing unevenly and independently from one another, resulting in incomplete and inefficient use of available resources. In the field of crop production, the main problems include small land plots, declining soil fertility, lack of investment, and low production efficiency. Livestock farming is constrained by the insufficient use of pasture and feed resources, leading to low profitability. At the same time, aquaculture, although comparatively profitable, places significant pressure on water and land resources, creating environmental risks. The research demonstrates that the existing land, water, and human resources of these communities provide an opportunity to establish a more efficient and profitable agricultural system. For this purpose, a development model based on inter-community cooperation and permaculture principles is proposed, including land consolidation, the introduction of a five-field crop rotation system, feed production organization, and the integrated development of livestock farming and aquaculture. Based on the results, an integrated development model is proposed, grounded in inter-community cooperation and permaculture principles. The model includes land consolidation, the implementation of crop rotation systems, and the establishment of a sustainable feed base. The proposed "Sis–Ranchpar–Hovtashat Agro Cluster" system can contribute to increased productivity, higher incomes for farming households, reduced environmental risks, and the long-term socio-economic sustainability of the studied rural communities.