Tomato production in greenhouse in warm climate faces the challenge of maintaining productivity during the critical period of high temperature. In the state of Morelos, central part of Mexico, temperatures above 45 degrees C and relative humidity below 20% are common inside the greenhouses every day from March to June, which impairs productivity and fruit quality compared to the rest of the year. Two trials were conducted, from March to July and from August to December 2010 to evaluate productivity of tomato ('Ramses') in greenhouse, as well as presence of fruit quality related disorders like blossom end rot, and water and fertilizer efficiency use. In both trials, performance of volcanic scoria (tezontle) and coir as substrates was evaluated, under open and closed system. In the first trial, water used came from a well (100 m deep), while in the second trial water used came from rainfall, collected from the roof of a greenhouse. There were highly significant differences in productivity between trials: 1.748 kg fresh fruit plant(-1) in April-July vs. 5.134 kg fresh fruit plant(-1), in August-December. There were many problems in balancing nutrient solutions during March-July due to high requirement of Ca2+ in solution to avoid blossom end rot. Use of coir as substrate increased efficiency of production in both trials because reductions from 20 to 30% in water demand and cost of fertilizer compared to volcanic scoria, with no reduction in fruit yields. Use of rainfall water from August-December facilitated the use of the closed system, achieving yields and fruit quality similar to the open system. Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis was the main phytopathological problem in the closed system with coir as substrate.
