Effects of the Organic Fertilizers and Modified Evaporative Cooling System on the Productivity of Tomatoes Greenhouse in Hot and Humid Regions

In hot and humid climates such as the tropics, coastal areas of the subtropics and Mediterranean basin, crop growth in greenhouses during hot and humid summer is almost impossible because of the high temperatures occurred inside cause plant stress and death. The aim of this experimental work was to investigate the effects of a developed evaporative cooling system and using different rates of dried biogas digester residues as organic fertilizer on the growth, productivity, and fruit quality of tomato crop. Two similar gable-even-span greenhouses were utilized at EL-Sabahia Horticultural Research Station, Alexandria, to grow and produce tomato crop during the summer seasons of 2014 and 2015. Each greenhouse was equipped with a complete evaporative cooling system. One of them was modified (MECS) by utilizing a solid desiccant. The other one used fan-pad system, (FPECS). The obtained data revealed that the average indoor temperatures, relative humidity and vapor pressure deficit of the MECS greenhouse were lower than the FPECS greenhouse. At noon, the maximum greenhouse temperatures decreased below the outside temperature by 2.2 oC for MECS while, it increased by 1.6 oC for FPECS. The maximum indoor temperatures were 42.2, 28.8 and 31.7 oC for un-cooled, MECS, and FPECS greenhouses, respectively. The greenhouse temperatures decreased at noon below the outside temperature for MECS 3.2 and 1.3 oC while, it increased by 1.6 and 1.6 oC for FPECS, for the emissive and highly solar radiation days, respectively.  Organic fertilizers, (dried biogas digester residue at 30, 20, and 10 m3/fed and farm yard manure at 20 m3/fed) were applied to investigate their effects on growth, yield and quality as well as chemical constituents of tomato plants. Results of this work showed that the application of 30 m3/fed of dried biogas digester residue significantly increased the vegetative growth, yield and fruit quality of tomato crop. Meanwhile, there were no significant differences between the application of 30 and 20 m3/fed applications in most studied characters. The results showed also, that farm yard manure application at rate of 20 m3/fed surpassed the 10 m3/fed application of dried biogas digester residue with no significant differences. The increase percentages in early yield, number of fruit per plant, fruit weight, total yield per plant and total yield per feddan were 21.28, 14.28, 14.60, 7.56, 23.03 and 23.03%, respectively for 30 m3/fed dried biogas residue over farm yard manure, (20 m3/fed) while, they were 18.91, 13.57, 6.40, 20.65 and 20.65% in 2014 and 2015 seasons, respectively. It can be concluded that application of 30
m3/fed dried biogas residues was the best treatment to produce the highest vegetative growth, yield and quality of tomato plants.