Avaliação de técnicas de conservação de água em lavoura comercial de tomate de mesa

Abstract

The tomato is a water demanding crop among the most purchased vegetables in Brazil. The search for alternatives that improve its yield, able to reduce the use of water is essential for agricultural and the environment. Thus, three experiments were set up with the objectives to evaluate influence of plastic cover and subsurface drip on the production and efficiency variables in the use of water in salad tomato field. In the first one, we attempted to compare two water application rates (TA1 e TA2) in conjunction with plots using plastic and subsurface dripping and their effect on production variables, soil moisture and tomato water use efficiency. A completely randomized factorial design (DIC) with 2x2 scheme and nine replications was used. It was observed that the water content in the soil remained within tolerable limits for irrigation management, except in the maturation period, between 90 and 100 DAP. There was no statistical difference for production variables. The water application TA1 presented a statistically superior value of water use efficiency for total (39.53 kg m -3 ) and market (35.47 kg m -3 ) production. In the second experiment, pulsed irrigation (6 applications) and continuous irrigation were compared in conjunction with surface and subsurface drip irrigation. A completely randomized factorial design (DIC) with factorial 2x2 with six replications was used. The soil matric potential presented similar behavior as function of soil depths 0.10; 0.30 and 0.50m. There was no significant statistical difference for production variables. No significant statistical differences were observed in applying water continuously, in 6 pulses per irrigation, superficial or subsurface. Soil water content remained above field capacity moisture during the experimental period, which may restrict soil aeration and root system development. In the third experiment, two irrigation rates (TA1 and TA2) were compared in combination with surface and subsurface drip irrigation. A completely randomized factorial design (DIC) with factorial 2x2 with six replications was used. It was noted that the electrical conductivity of the saturation extract remained below the limit (2.5 dS m -1 ). Plants showed no signs of saline stress. No significant statistical differences were observed for production variables. The water application TA1 presented a statistically superior value when compared to TA2 in water use efficiency for total (20 kg m -3 ) and market (18 kg m -3 ) production. In general, after evaluating results of all three experiments, it is possible to conclude that lower irrigation application rates result in larger water use efficiency. Mulching use revealed to be a suitable alternative for subsurface drip irrigation, but it impacts on reduction of labor and soil pollution must be investigated. Pulse irrigation didn´t show advantages because all experiments were carried out during rainy season.