Abstract
Increasing food security and water shortages need creative agricultural methods, especially in dry places like Algeria. This research examines an Arduino-controlled smart greenhouse system for hydroponic barley growing, addressing the demand for resource-efficient farming. The experiment at the University of Tebessa (34°09'16"N, 8°07'44"E) used a semi-cylindrical greenhouse (0.65m × 0.70m × 0.65m) with DHT22 sensors for temperature and humidity monitoring, photoresistors for lighting control, and controlled watering systems. The approach yielded 26% more barley (120g vs. 95g) in 10 weeks instead of 12 weeks. Compared to soil-based approaches, water use efficiency reached 50 g/L, a 70-90% decrease. Optimizing energy usage to 150 kWh saved 9% over prior smart greenhouse systems (165 kWh). To achieve 95% nutrient absorption efficiency, the automated control system maintained ideal growth conditions at 20-25°C and 60-80% relative humidity. Compared to conventional approaches, key performance indicators revealed significant improvements: average plant height grew by 18%, tiller count increased by 33%, and leaf area extended to 1000 cm². A semi-cylindrical design increased spatial efficiency by 20% and reduced disease outbreaks by 10%. These findings show that Arduino-based smart greenhouse technology may boost barley production efficiency and minimize resource usage, making it a viable alternative for sustainable agriculture in dry locations.

Key words: Hydroponics, Smart greenhouses, Arduino, Barley cultivation, Automation, Sustainability.