Overcoming seed dormancy and evaluation of viability in Leucaena leucocephala

Abstract

Leucaena leucocephala is an arboreal legume with many applications in agriculture (forage, wood production, charcoal, soil improvement, shading, windbreak, and hedge). Its seeds show dormancy, which is caused by physical blockade through resistant and impermeable integument. The aims of this study were to evaluate and determine efficient methods for overcoming dormancy in Leucaena leucocephala seeds. The experiment was carried out in Tangar da Serra city, Brazil, adopting a completely randomized design, with four replications. The treatments consisted of no scarification (T0), scarification with sandpaper (T1), immersion in concentrated H2SO4 for 5 min (T2), 10' (T3), 15' (T4), and 20' (T5), and immersion in water at 80 C for 5' (T6), 10' (T7), 15' (T8) and 20' (T9). The seeds were placed in germination chamber at a temperature of 25 C and photoperiod of 12 hours day/night over a period of 10 days, for all treatments, using 50 seeds per replicate. The experimental data were submitted to analysis of variance (type I error) by F test (p<0.05) with comparison of averages performed by Tukey test (p<0.05). The treatment that showed best efficiency in overcoming seed dormancy was immersion in concentrated H2SO4 (density of 1.84 and purity of 95%) for 20 min, with 93.0% of viable seed germinated. Immersion of seeds in water at 80 C for 20 min (0.0% seed germination) showed lowest efficiency in overcoming dormancy of Leucaena leucocephala seeds. It was concluded that treatment with immersion in concentrated H2SO4 for 20 min is the most efficient in overcoming dormancy of Leucaena leucocephala seeds, showing higher values of first germination count, germination percentage, germination speed index and average time of germination.