Crescimento inicial de três espécies da caatinga sob diferentes doses de fósforo

Abstract

Phosphorus is found in low content of tropical soils, affecting the growth and production of native species. The objectives of this study were to evaluate the effect of phosphorus levels on the initial growth and phosphorus nutrition of three forest species: Piptadenia stipulacea (white jurema), Libidibia ferrea (jucá) and Erythrina velutina (coral tree). The experiments were conducted in a greenhouse located at the Agricultural Research and Education Center in Urbana (NEPAU), Department of Plant Science of Agricultural Sciences Center of the Federal University of Ceará, in Pici campus. The substrate used was soil Argissolo Yellow kind collected in the surface layer (0-20 cm). Polypropylene bags are used, with a capacity of 1.0 dm-3 of soil. The experimental design was randomized blocks with five phosphorus doses (100, 150, 200, 250 and 300 mg dm-3) and five repetitions, totaling 25 installments, with six plants each. Sixty days after planting species, measured the plant height, stem diameter, number of leaves, dry weight of shoots and roots, it was determined the relationship height / stem diameter, dry matter shoot / root, quality index of Dickson, content and phosphorus accumulation in shoots and phosphorus use efficiency. The results indicate that the soil under study has a low phosphorous fixation capacity. Based on the growth characteristics evaluated in seedling production phase, the jucá has low potential response to fertilization on soil with low phosphorus fixation capacity while white jurema and coral tree have moderate potential, with phosphorus levels above 100 mg dm-3 of soil. The jucá has low requirement and high phosphorus use efficiency, and can be grown in soil with low content of that nutrient. jurema white coral tree and present phosphorus luxury consumption and hence lower efficiency of use of this nutrient.