Development and quality of Parkia gigantocarpa Ducke (Fabaceae) seedlings using controlled-release fertilizer

Abstract

Parkia gigantocarpa belongs to the group of pioneer and light-demanding species and their main ecological characteristic is rapid growth, and this species is highly recommended for gap recovery and forest restoration projects. This study aimed to investigate the effects of increasing doses of controlled-release fertilizer (CRF) during the initial development of P. gigantocarpa seedlings. The study was conducted in a greenhouse under 50% shade conditions, for a period of 90 days after the seedlings were transplanted. A completely randomized design with four treatments and eighteen repetitions was used. The treatments consisted of four doses of Osmocote^® (0 - 4.1 - 8.2 and 12.3 g dm^-3) in the NPK formulation (15-09-12). The results showed that most of the phytometric parameters and gas exchanges responded significantly well to intermediate doses of CRF, which could be confirmed by the increases in leaf number (LN), leaf area (LA), total dry mass (TDM), Dickson's quality index (DQI), and net photosynthetic rate (P_N). Furthermore, significant reductions in intercellular CO₂ concentration (C_i), were also noted showing that the seedlings displayed higher stomatal and photosynthetic apparatus efficiency. Thus, CRF contributed positively to the initial growth of P. gigantocarpa seedlings, and a dose of 4.1 g dm^-3 of Osmocote^®, which is 50% of the dose recommended by the manufacturer.