African mahogany submitted to drip irrigation and fertilization

Abstract

African mahogany (Khaya ivorensis A. Chev.) is a tree species that has been increasing in Brazilian commercial planting. However, the lack of water and nutrition are great obstacles for crop production. The aim of this study was to evaluate the growth of young mahogany plants submitted to drip irrigation and topdressing. The experimental design was of randomized blocks, with three repetitions in subdivided plots. Treatments consisted of drippers: 1, 2 and 3plt-1; flows: 2, 4 and 8L h-1, and a treatment without irrigation. For topdressing, subplots levels were, as follows: 1) 17.5 and 25.2; 2) 35.1 and 50.1; 3) 52.5 and 75.0; 4) 70.0 and 100.2; and 5) 87.5 and 125.1 g plant-1 N and K2O, respectively, divided into five bimonthly applications, which started in the 4th month after planting. Plant height, diameter at root collar and at breast height (DBH), and stem height were evaluated. Results showed statistically significant differences (P>0.05) between irrigated and non-irrigated plants. Mean plant height ranged (from 2 to 20 months in field) from 0.33 to 3.25 and 2.67m for irrigated and non-irrigated plants, respectively. Mean stem height ranged from 0.23m to 0.87 and 0.71m for irrigated and non-irrigated plants, respectively. Thus, irrigation with 1 dripper per tree and flow of 2L h-1 was able to supply mahogany water requirements in the first two years in field. Trees have not responded to N and K topdressing at the beginning of the cycle.