Efeito de retardantes de fogo sobre a germinação de espécies florestais tropicais

The objective of this study was to evaluate the effect of different concentrations of fire retardants and water-retaining polymer on seed germination of tropical forest species Handroanthu simpetiginosus (ipe-rosa), Tabebuia roseoalba (ipe-branco), Enterolobium schomburgkii (faveira) and Schizolobium parahyba var. amazonicum (parica). It is noteworthy that no comparisons were made between the products, as they have different commercial recommendations and chemical compositions. The seeds were submitted to solutions of three fire retardants in the following concentrations: i) Phos-Chek WD881® at 0.0; 0.1; 0.3; 0.6; 0.8 and 1.0 mL L -1 ; ii) Hold Fire® at 0.0; 0.7; 0.9; 1.1; 1.3 and 1.5 mL L -1 ; and iii) water-retaining polymer Nutrigel® at 0.0; 0.10; 0.25; 0.50; 0.75 and 1.0 g L -1 . Four replicates of 100, 100, 30 and 25 seeds were evaluated for the aforementioned species, in a completely randomized design. The germination tests were conducted in germination chambers at 30°C and 12 hours of photoperiod for 14 days. It was evaluated: germination percentage, first germination count, germination speed index, average germination time and seedling vigor were evaluated. Phos-Chek WD881 reduced the germination speed of the ipes and the first germination count and number of normal seedlings of these species and parica. Hold Fire influenced the germination percentage of ipe-rosa (maximum 97.0% in 1.1 mL L -1 ) and the germination speed of ipe-branco, but did not cause variations in seedlings vigor. The water-retaining polymer did not influence germination, but caused a 14.3% reduction of normal seedlings to parica. In general, Phos-Chek WD881 can be phytotoxic to ipe-branco, ipe-rosa and parica, when applied in concentrations ≥ 0.6 mL L -1 ; Hold Fire can promote the germination of ipe-branco and ipe-rosa, without effects for the other species; and the water-retainng polymer had no effect on the seed germination of the evaluated forest species.