Níveis de água e nitrogênio na cultura do cacau no semiárido baiano.

Abstract

The growth of cocoa seedlings and the effect of irrigation and nitrogen fertilization on the growth characteristics and productivity of cacao {Theobroma cacao L.) CCN-51 clone, was verified in an experiment conducted in a greenhouse and in the field of the Hydroagricultural property in Vale do Sol Jequié-BA. The nursery shaft had 50% shading, micro-sprinklers reversed to the height of 0.60 m and an area of approximately 630 m2 with a ceiling height of 2m. The experimental field had an area of 1792 m2 planted with clones spaced 3.5 x 2 m, where were applied 4 irrigation regimes, based on the gross irrigation depth (GD) 0.60, 0.80 ,1.0 and 1.2 GD, inferred from a Class "A" Evaporation Pan installed on the farm. The fertilizer doses applied were 70, 100 130 and 160% of the recommended nitrogen for the cocoa cultivation. The statistical experimental design was a 4 x 4 factorial, randomized blocks with four replications, where the water depths and nitrogen factors were combined resulting in 16 treatments. In the nursery was measured the plant height, stem diameter and leaf number; at the field the plant height, stem diameter and the yield components (number of fruits per plant, length, diameter ffuit, ffuit weight, number of seeds per fruit, weight of kernel and productivity). The water depths and nitrogen doses used in this study influenced the plant height and stem diameter, while the interaction of water and nitrogen did not affect these characteristics. The amount of water, the nitrogen and the interaction between them influenced positively the production of dry beans and fruit number per plant of the cocoa. In the field the use of 1922.52 mm of water and 493.10 kg ha"1 nitrogen promoted the highest productivity of commercial cocoa beans, 1025.69 kg ha"1. The optimal combination of water depth and nitrogen was 1926.23 mm and 560.70 kg ha"1, nitrogen giving a yield of 1649.23 kg ha"1 of dry cocoa beans.