Growth analysis of tomato plants in controlled greenhouses

Greenhouses are used to maintain an ideal plant growth by controlling environmental conditions. A study was conducted in two polycarbonate covered greenhouses under Riyadh climatic conditions. Some energy and water saving techniques were applied in one greenhouse (G1) including; shading during summer, natural ventilation during winter and spring days, and thermal screens during cold winter nights. The second greenhouse (G2) was kept without any of these techniques. Both greenhouses were equipped with fan-pad evaporative coolers, and hot air generator fueled by diesel. In addition, an automatic control system was designed for operation of ventilation, cooling, and heating systems, and energy and water saving techniques. Plant growth, yield and quality traits of tomato crop were compared under G1 and G2 conditions. Four weeks tomato ('Valouro RZ F1') seedlings were transplanted into rockwool slabs. Vegetative parameters (leaf area, stem length, fresh and dry weights of leaves and stems, stem diameter) were measured at 14 days intervals. Fruit and yield traits (fruit length, diameter, fresh weight and number and total yield) were recorded at each harvest time. Plant growth indices were calculated: leaf area index (LAI), leaf area duration (LAD), leaf weight ratio (LWR), stem weight ratio (SWR), fruit weight ratio (FWR), specific leaf area (SLA), leaf area ratio (LAR), net assimilation rate (NAR), relative growth rate (RGR) and crop growth rate (CGR). Climatic data inside and outside the greenhouses were also recorded. Plants grown under G1 were superior in vegetative growth traits with the highest quality traits (vitamin C content, total soluble solids and total acidity). Growth analysis data indicated that tomato plants in G1 had faster growth rate due to the optimum environmental conditions provided by the automation control system.