Desempenho da cana-de-açúcar, quinta folha, sob diferentes níveis de irrigação e adubação de cobertura nos tabuleiros costeiros da Paraíba.

Abstract

The sugar cane plant makes distinction in the Brazilian agricultural scenery as the largest producer in world, and with the drought problem in the Northeast semi arid region, it is necessary the irrigation technical to assure its production. With the objective of studying the development of the sugarcane (Saccharum officinarium L., variety SP 79-1011), fifth leaf, under different irrigation levels and two covering fertilization, it was installed in the Capim Farm at Miriri distillery, Paraiba State. The experiment was constituted of a 2 x 4 factorial scheme (two covering fertilization levels: N0 e N1, and four water depth: W0, W1, W2 e W3) with four replications, and a total of 8 different combinations. The irrigation factor were W0 = 0; W1 = 193; W2 = 385 e W3 = 578 mm. The water was applied through mobile pivot center irrigation system, in intervals of 12 days, and the evapotranspiration value was calculated based on Class A Evaporation Pan, taking out the effective precipitation. The total amounts of applied water (irrigation plus effective precipitation) were W0 = 671; W1 = 864; W2 = 1056 e W3 = 1249mm. The covering fertilization factor were N0 = 0 kg ha-1 e N1 = 180 kg ha-1 (70 kg ha-1 of nitrogen and 110 kg ha-1 of potassium). Amongst the analyzed parameters, the growth, technological and of production, production of stem and gross percentage of sugar were not influenced by the irrigation factor and not by the covering fertilization factor. The irrigation factor had influences in the number and length of the stems, number of internodes, POL, purity, production of stems, gross income of the sugar and alcohol, while the covering fertilization factor had influences on the number, length, diameter fiber and production of stems, and also in the gross income of the sugar and alcohol. There was an increment in the length of stems, weight of stems, number of internodes, ºBRIX, POL, gross percentage of sugar, productivity of stems, gross income of sugar and alcohol, with an increase on irrigation level in the treatment with larger amount of covering fertilization.