Métodos para a superação de dormência de sementes de Juerana branca (Albizia pedicellaris (DC) L. Rico) na Amazônia Oriental

Abstract

The Albizia pedicellaris is a native species of Brazilian forests that contributes to the biodiversity of native forests, assisting in maintaining the edaphoclimatic characteristics of the region. This species that presents increasing number of seeds when it reaches the reproductive stage. However, these seeds present tegumentary dormancy, prolonging germination time, and these factors are limiting factors for the uniform obtaining of seedlings of this species. The objective of this work was to evaluate different pre-germination methods to promote the overcoming of dormancy of white Juerana seeds (Albizia pedicellaris), aiming to obtain the highest number of normal seedlings. The experiment was conducted at the Didactic Laboratory of Seed Analysis of the Federal Rural University of the Amazon, Campus, in Belém do Pará. The following methods of overcoming dormancy of orthodox seeds were used: intact seeds (T1), desponte das sementes (T2), top lopping more imbibition under water for 24 h (T3), immersion of seeds in sulfuric acid at 10 minutes (T4), immersion of the seeds in sulfuric acid at 20 minutes (T5), immersion in sodium hypochlorite at 2.2% for 3 h (T6) and immersion in sodium hypochlorite at 1.1% for 3 h (T7). The experimental design used was completely randomized, with seven treatments, containing four replications. The weight of 1000 seeds were calculated, the water content of 4 replicates of 40 seeds was determined, it was calculated by means of the biochemical method at 105ºC (±3) for 24h. Pre-germination tests were performed on germitest towel paper ®, incubation was done in germination chamber (Oxygen Demand - B.O.D), at 25ºC (±3) for 10 days, where the germination of the best treatments was established. Germination parameters (%G), germination speed index (IVG), average germination time (TMG), Shoot length (CPA) and root length (CR) of normal seedlings were analyzed. The weight of shoot dry mass (MSPA) and root dry mass (MSR) was determined, the number of normal seedlings, abnormal seedlings, hard seeds and dead seeds was analyzed at the end of the experiment. The data were submitted to variance analysis using the Student-Newman-Keuls test (SNK) at 5% using the Softwere R- Studio. The seeds of A. Pedicellaris replaced well to the treatments whose immersion was in sulfuric acid at 10 min (T4) and 20 minutes (T5) and to the treatment with top lopping (T2) the treatment with top lopping more imbibition in water for 24 hours presented lower germination percentage and higher number of dead seeds. Being the treatment with desponte (T2), the most indicated for the production of seedlings with more than 80% germination and with more cheap cost.