Enraizamento e crescimento de abacaxizeiro em resposta à aplicação de ácido 3-indolacético e de fosfato monoamônio

Abstract

Pineapple root system has a low development, with high concentration of roots in the superficial layers of soil. Root induction through auxin and nutrients might accelerate plant growth, with consequent decrease in production cycle. The objective of this study was to study plant growth and rooting of pineapple under the influence of 3-indoleacetic acid (AIA) and monoammonium phosphate (MAP). The experiment was conducted under greenhouse conditions, with a 5 x 5 factorial arrangement, corresponding to five concentrations of AIA (0; 250; 500; 1.000; and 2000 mg L¹) and five concentrations of MAP (0; 4.834,3; 9.668,8; 14.503,2; and 24.172 mg L¹), totalling 25 treatments. The experimental design was completely randomized, with five replicates, each plant being one replicate. The following evaluations were made: total height; total fresh and dry matter of plant, leaves, D leaf, stem and roots; length of D leaf, stem and root; root volume; total leaf area and D leaf; average width of D leaf; absolute and relative growth rates; leaf area ratio; specific leaf area; leaf weight ratio and root/aerial part ratio. Significant models were adjusted for all variables evaluated, except specific leaf area, leaf weight ratio and dry mass of D leaf. The immersion of conventional pineapple seedlings in solution containing 2.000 mg L¹ of AIA and 6.500 to 8.200 mg L¹ of MAP promotes greater plant growth and consequent reduction of the production cycle. The concentration of 2.000 mg L-¹ of AIA plus MAP concentration of 5.300 to 7.300 mg L¹ favors the rooting of the conventional pineapple seedlings. The leaf area of pineapple D leaf can be estimated from the length and width of this same leaf and the total leaf area can be estimated from the D leaf area.