Banca de DEFESA: BRENDA STEPHANIE DE OLIVEIRA CHAVANTE

BIOMORPHOLOGICAL CHARACTERIZATION OF FRUITS AND SEEDS AND ECOPHYSIOLOGY OF SEED GERMINATION OF Tephrosia noctiflora Bojer ex Baker.

Weeds, physiological potential, Tephrosia noctiflora.

Tephrosia noctiflora (Bojer ex Baker), is an endemic species of Brazil, being found in areas of grains, sugarcane and pastures in the state of Alagoas, causing negative impacts on production. The literature presents little information regarding the species, in this sense the objective of this work is to biomorphologically characterize the seeds of Tephrosia noctiflora, record the post-seminal development and study the physiological potential as a function of germination, temperature and pH. The seeds were collected in the municipality of Atalaia – AL, and the tests were conducted in the plant propagation laboratory of the Federal University of Alagoas, located in the municipality of Rio Largo. For physical characterization, the weight of one thousand seeds, number of seeds per kilogram, length and width were evaluated, and the means for each variable were calculated. In the morphological characterization, it was verified the shape of the seed, its coloration, location of the embryonic axis, type of germination. The evaluation of the physiological potential was performed using eight treatments to overcome dormancy (T1 - control, T2 - water bath 45°c for 20 minutes, T3- thermal shock, T4- 5 minutes sulfuric acid, T5- 10 min. sulfuric acid, T6- 15 min. sulfuric acid, (T7)- 20 min. sulfuric acid, T8- 25 min. sulfuric acid) and two temperatures being one constant and the other alternating (30 and 20-30°C),  using a completely randomized design mounted in an 8X2 factorial scheme (treatments x temperature) with four replicates of 25 seeds each. The variable studied was germination percentage. After the best treatment was defined, post-seminal development was monitored and recorded. After this phase, the physiological potential of the seeds was evaluated as a function of pH (2.5, 4.0, 5.5, 7.0, 8.5 and 10). The experiments were carried out in a completely randomized design (DIC), and the data were submitted to analysis of variance, whose means were evaluated by Tukey's test at 5% and regression analysis for quantitative variables. According to the results obtained, it was found that the weight of one thousand seeds was on average 0.81g, corresponding to 1,234,568 seeds/Kg. The seed dimensions ranged from 3.18 to 1.27 mm in length, by 2.20 to 1.04 mm in width, with humidity of 7.58%. The shape of the seed is reniform, the integument has a rough surface in brown coloration. The embryo is of the axial type and the germination is of the epigeal type. In the evaluation of the physiological potential, the best germination percentage (85%) was obtained with the use of sulfuric acid for 25 minutes at a constant temperature of 30°C.  The species did not suffer great influence of the pH maintaining germination higher than 50% in all the tested ranges, the ideal pH of the species is 7.67 with 93% of germination.