Efeitos de lâminas de água e de fertilidade na cultura do tomate industrial.

Abstract

This study was carried out during the period from August 1980 to January 1981, in the Irrigated Perimeter of Itans / Sabugi, belonging to the National Department of Works against Droughts, in the municipality of Caicó, Rio Grande do Norte, to study the effects of four irrigation, three levels of nitrogen and three levels of phosphorus, on the productivity and number of fruits per hectare of tomato, IPA-2 cultivar, using the "in-line sprinkler" irrigation system, the trial was conducted in eutrophic alluvial soil, in a randomized complete block design with four replications, with the treatments in strip if the sub treatments in 3 x 3 factorial arrangement. The total water applied slides were 1.032; 923; 796 and 584 mm, produced by the different water distribution from the sprinkler axis. For the measurements of the slides containers were installed in the center of each experimental plot. The nitrogen levels applied were 0, 60 and 120 kg / ha of N, based on ammonium sulfate. The applied phosphorus levels were 0, 75 and 150 ka / ha of P205, with the single super phosphate as the source. Potassium was uniformly applied at a dose of 70 kg / ha K 2 O in the form of potassium sulphate. In order to determine the evapotranspiration of the crop, irrigation control and water content changes were carried out on the soil profile through daily measurements. Evapotranspiration was estimated by the water balance equation. It was verified that the irrigation depths 796 and 923 mm were and statistically equal and responded better to the increase in productivity and the number of fruits / ha during the studied period, indicating that the use of the water blade can be reduced to 796 mm without affecting productivity. The application of water increased productivity significantly in a quadratic relation up to the level of 923 mm, with a slight decrease in the range of 1,032 mm, obtaining a maximum productivity of 71.5 t / ha with the level of 864 mm of water. The number of fruits / ha increased in a quadratic relation with the increase of the amount of water applied to the crop, reaching a maximum of 1,771,500 fruits / ha with the irrigation range of 923 mm. The productivity and number of fruits / ha increased linearly with increasing levels of nitrogen and phosphorus, demonstrating that the culture would respond to higher doses of these fertilizers. Higher net profit was achieved with the dose of 150 kg / ha of N associated with 150 kg / ha of P205, using 70 kg / ha of K20 as the basic dose.