Resumen
- Plastic greenhouses are used for the production of cut flowers and tomatoes in the high altitude tropics. One of the major problems of tomato growing in the Bogotá Plateau (2650 m altitude and 5º north latitude) is the low night temperature, causing stress and low average greenhouse temperatures. Before growers invest in greenhouse technology, they want an estimation of the cost-benefit ratio of the project. For these purposes, models are increasingly useful to simulate the greenhouse climate and the growth and production of crops. The TOMGRO model describes the phenological development and the increase in dry matter of the different tomato plant organs, under dynamically varying climate conditions. The second version of this model is used for the evaluation of the traditional greenhouse with open ridge plus five greenhouse adaptation strategies: greenhouse with automated roof vents (GHV), simple greenhouse with thermal screen (GHS), roof-vent greenhouse with thermal screen (GHVS), and two options heated at a minimum of 18°C (GHS18 and GHVS18). Climate improvement through the implementation of greenhouse accessories leads to shorter vegetative periods and higher productivities. Simulations for GHS18 and GHVS18 maximized productivity but investment and maintenance costs of the heating system decreased the profitability. Simulations with the climate data generated by the use of thermal screens or roof ventilation showed the highest benefit-cost ratios. The maximum productivity and gross income are achieved as the average greenhouse temperature increased, indicating that the low average temperature of the Bogotá Plateau is a limiting factor for tomato production.