Produção do abacaxizeiro 'Vitória' irrigado sob diferentes densidades populacionais, fontes e doses de nitrogênio

Abstract

The pineapple crop is considered highly profitable and it presents important social role for generation of jobs in the producing areas. The production in Brazil is based on two cultivars, ‘Smooth Cayenne’, destined preferentially to industry, and ‘Pérola’ destined to consumption ‘in natura’. However, both cultivars are susceptible to fusarium wilt that is the main disease of the pineapple crop in Brazil. The cultivation of resistant materials shows a control alternative more efficient and economical of solving that obstacle. The ‘Vitória’ cultivar appears as positive perspective for solution of that problem and it can be used, so much for the consumption ‘in natura’ as for the agribusiness. The nitrogen is one of the most required nutrients by the pineapple crop, being responsible for the yield and quality of the fruits. On the other hand the population density also influence in those variables. This work aimed to evaluate the effect of different population densities, sources and doses of nitrogen on the growth, yield and quality of the 'Vitória’ pineapple fruits. The experiment was set in July of 2009, being used plants micropropagated of the ‘Vitória’ cultivar. The used design was in blocks at random, with three repetitions, being the experimental units arranged in a factorial scheme 2 x 5 x 4, corresponding to two sources of N (urea and bovine manure), five doses of N (0, 5, 10, 15 and 20 g plant-1) and four plants populations (51.282; 76.923; 90.909 and 126.984 plants ha-1), totaling 40 treatments. The pineapple growth in the time it was observed with the evaluation of the following characteristics: number of emitted leaves, length of “D” leaf and stem diameter. At that time of the flower induction, "D" leaves were collected for determining weight and their nutritional contents and it was determined leaf index. At harvest the medium weight of the fruits was evaluated with and without crown, length and diameter of them, medium number of sprouts per type (sucker and slip sucker) and per plant. They were also determined pH, Total Soluble Solids (TSS), total titratable acidity (TTA) and TSS / TTA relationship of the fruits pulp. The increase of the planting density reduced the stem diameter of the ‘Vitória’ pineapple, as for the addition of N in the urea as for the manure. When urea it was used, the increase in the dose of N up to 20 g plant-1 provided increment in the “D” leaf length and stem diameter of the in the ‘Vitória’ pineapple irrigated. The growth of the ‘Vitória’ pineapple evaluated by the characteristics number of leaves, length of the “D” leaf and diameter of the stem presented lineal increment with the increase of the time of cultivation to the phase of floral induction for the two sources of studied N. The urea promoted the largest values for the productivity variables, as well as the leaf area index and weight of the "D" leaf. The addition of N as manure resulted in leaf content higher of nutritients. The population density did not interfere on the weight of the fruits, however larger densities resulted in greater productivity. There was not effect of population density on the leaf index. However, nitrogen fertilization promoted increase in the fruit weight and productivity, leaf index and weight of “D” leaf, besides interacting with the leaf content of the nutrients. Dose of N and population density close of the highest tested ones provided greater productivity of fruits with and without crown for both used sources.