Substrato e adubação fosfatada para a produção de mudas clonais de cacau

Abstract

The effect of potting mix and phosphate fertilization on the production of rooted cocoa tree cuttings was evaluated and recommended rates and critical foliar P levels were determined based on a factorial 5 x 5 + 1 experiment: five potting medium (coconut fiber - CF and Plantmax® mix), five P rates at planting (0 to 800 mg dm-3) and an additional P treatment (applied on the 30th day). Each plot contained 27 cuttings, of which 12 rooted cuttings were evaluated. From the 62nd day onwards, N and K fertilization was weekly applied as well as a P fertilization on the 120th day (20 mg dm-3), to all treatments. The diameter, height, leaf area, shoot and root (fine and thick) dry matter, nutrient concentration and content in plants were evaluated on the150th day. Cutting mortality was not influenced by the treatments. Phosphorus top dressing increased P assimilation and absorption, but not the growth of the rooted cuttings. The biometric and nutrition variables responded to treatments; best results were obtained with 30-55 % of CF and P rates between 136 and 275 mg dm-3. The foliar critical level of P was 1.75 g kg-1.