Avaliação do potencial fisiológico de sementes de Tephrosia noctiflora Bojer ex Baker

Abstract

The Tephrosia noctiflora (Bojer ex Baker) is an endemic species in Brazil, found in pastures and cultivated areas in the state of Alagoas, causing negative impacts on production. The objective of this study was to morphologically characterize the seeds of Tephrosia noctiflora, study the physiological potential based on different pre-germinative treatments, temperature, and pH. The seeds were collected in the municipality of Atalaia, Alagoas, and the experiments were conducted at the Plant Propagation Laboratory of the Federal University of Alagoas, located in the Campus of Engineering and Agricultural Sciences, in the municipality of Rio Largo. For physical characterization, the number of seeds per kilogram, length, and width of each seed were evaluated, with results assessed by mean, mode, and median. In morphological characterization, the seed shape, color, location of seed structures, type of germination, and seedlings were examined. The evaluation of physiological potential was carried out using eight pre-germinative treatments intended to accelerate and standardize seed germination: T0 – Control (intact seeds); T1 – immersion of seeds in a water bath at 45°C for 20 minutes; T2 – thermal shock (immersing seeds in boiling water followed by cooling in running water); T3 – immersion of seeds in sulfuric acid (H2SO4) for five minutes, 10 minutes (T4), 15 minutes (T5), 20 minutes (T6), and 25 minutes (T7). After each treatment, the seeds were incubated in a BOD-type germinator set at two temperatures, constant at 30°C and alternating between 20- 30°C. The design was completely randomized in an 8X2 factorial scheme (treatments x temperature), with four repetitions of 25 seeds each. The physiological potential of the seeds was evaluated at different pH levels (2.5, 4.0, 5.5, 7.0, 8.5, and 10), in a completely randomized design (CRD). For the obtained data, analysis of variance was performed, and means were assessed by Tukey's test at 5% significance level, and regression analysis for quantitative variables. According to the results, seed dimensions varied between 3.18 to 1.27 mm in length and 2.20 to 1.04 mm in width. The seed shape is reniform, the tegument has a rough surface and brown color, and the embryo is axial. In the evaluation of physiological potential, sulfuric acid for 15 minutes proved effective in overcoming dormancy. Temperatures of 30 and 20-30°C can be recommended for laboratory tests. The species germinates over a wide pH range.