Agricultural Horizons: Research, Technology and Sustainable Development Vol. 2

Protected cultivation spans a wide technological continuum, from insect-proof net houses and high tunnels to passively ventilated polyhouses, solar greenhouses and highly controlled glasshouses. Its contribution to sustainable vegetable production is therefore not determined by enclosure alone, but by the degree of environmental control, climate, crop, energy source, root-zone system and management quality. This critical narrative review evaluates evidence published from 1 January 2000 to 30 June 2026 on the agronomic, environmental and socio-economic performance of protected vegetable systems. Particular attention is given to productivity and climate resilience, water and nutrient management, soilless cultivation, energy and life-cycle burdens, soil degradation, pest and disease control, product quality, economic feasibility and digital control. The evidence indicates that protected cultivation can markedly increase land productivity, stabilise production and improve water-use efficiency, especially where heat, cold, rainfall, wind, pests or water scarcity are dominant constraints. These advantages are most consistently realised in well-matched passive or low-energy structures and in precisely managed fertigation or recirculating systems. Sustainability gains are not automatic. Heated and intensively controlled greenhouses can carry large energy and carbon burdens; poorly managed soil-based greenhouses can accumulate salts and nutrients and lose nitrogen through leaching and gaseous pathways; and closed hydroponics introduces requirements for salinity control, sanitation and technical competence. Life-cycle studies also show that conclusions can reverse with crop, climate, functional unit and energy mix. Economic evidence is similarly conditional: season extension and yield premiums may offset capital costs, whereas market volatility, labour demand and technological risk can erode profitability. The most defensible strategy is therefore not maximum control but minimum effective control: matching protection intensity to the limiting production factor while integrating efficient irrigation, nutrient recycling, biological pest management, lower-impact materials, renewable energy where needed and locally validated decision support. Future research should prioritise multi-year, regionally diverse comparisons that report productivity, environmental footprints, economics and resilience on harmonised functional units.