Efeitos de diferentes lâminas de água e níveis de adubação de cobertura na primeira soca da cultura da cana-de-açúcar.

Abstract

This research was carried out at the Fazenda Capim of Miriri Distiiary, located in the county of Capim, PB, with the objective of identifying the sugarcane crop behaviour, on the first ratoon, as a response to different irrigation depths and fertilizers rate. An espejriment was setup using the SP79-1011 variety, in a factorial 4x2 arrangement, with there replicates ( four irrigation depths and 2 levs of surface applied fertilizers) . The adorted depth; were: Wo = no irrigation; Wi = 13,8 mm, W2 = 27,5 mm, W? = 41,3 mm, applied at 12 days interval through a movable center-pivot system: the quantities of water supplied to tie crop throug irrigation during it's cycle were: 0 mm, 179 mm, 358 mm e 537 mm, corresponding to the Wo, Wi, W2 e W 3 , treatments respectively, where the total water applied ( irrigation plus effective precipitation) was: Wo + Pcf = 807 mm, W t + Pef = 986 mm, W2 -+ Pe f = 1164 mm and W3 = 1343 mm. The levels of surface applied fertilizers used were: > 1 = 85 (level used by the farm corresponding to a 44 kg ha" of N and 41 kg ha" of K20); N2 = 305 ( 157 kg ha" of N and 148 kg ha" of K2)). Within the parameters analysed, BRIX] PCC, ARL and FIBER were not influenced neither by the irrigation factor or the surface applied fertilizer factor. The irrigation factor affected the length and diameter of the sta.k, the number of internodes and the POL. The surface appliede fertilizer factor affected the number, the length and the weight of the stalks, the PURITY, the stalk yiels, the gross yield of sugar and the gross yield of alcohol. The avaerage obtained were number of slalks = 76875 stalks ha", stalk length = 211,21 cm, stalk diameter = 22,68 mm, number of internodes = 21,33, stalk weight = 1001,75 g, stalk yields = 77,79 t ha", gross sugar yield = 10,73 t ha" and alcohol gross yield = 7,56 m3 ha". The maximum values were: number of stalks = 91,203,7 stalk ha", stalk length = 250 cm, stalk diameter = 25,4 mm, number of internodes = 23,7, stalk weight = 1148 g, stalk productivity = 104,23 t ha", gross yield of sugar = 14,02 m3 ha" and gross yield of alcohol = 10,02 mJ ha", all of which were reached with the W2N2 treatment.