Viability Mimosa bimucronata (DC.) O. Kuntze. seeds by the tetrazolium test and oil content Viabilidade de sementes de Mimosa bimucronata (DC.) O. Kuntze. pelo teste de tetrazólio e teor de óleo

Maricá (Mimosa bimucronata (D.C.) O. Kuntze.) is a species that presents great importance in reforestation programs, in the recovery of permanent preservation areas, landscaping projects and is considered soil improver, being recommended for erosion and for planting on flooded land. The objective of the present study was to evaluate the viability of the seeds of M. bimucronata by the tetrazolium test and to determine the crude oil content and the percentage composition of fatty acids. The experiments were conducted at the Plant Propagation Laboratory of the Agricultural Sciences Center (CECA) of the Federal University of Alagoas (UFAL), located in the municipality of Rio Largo, Alagoas, Brazil. The obtained data submitted to the analysis of variance and the comparison between the means of viable seeds for each of the combinations in the tetrazolium test were performed by the Dunnett test at 5%. The concentration of 0.075% tetrazolium salt for two hours at 35 °C is an efficient combination for evaluating the viability of M. bimucronata seeds. The oil content was 2.75%, with unsaturated fatty acids prevailing (63.8%).


INTRODUCTION
Maricá (Mimosa bimucronata (DC.) O. Kuntze.) belonging to the family Mimosaceae (Leguminosae-Mimosoideae), is a medium-sized tree species that is distributed naturally in the Northeast, South and Southeast regions of Brazil, being particularly frequent in the states of Pernambuco, Alagoas and Paraná. It is a species that presents great importance in mixed reforestation programs, destined to the plantation for the recovery of areas of permanent preservation, management of forest fragments and landscaping projects, due to its rusticity and fast growth (CARVALHO, 2003). It is also considered a soil improver and is recommended for the control of erosive processes and for planting on land subject to periodic flooding (CARVALHO, 2004).
In the tetrazolium test, procedures, called preconditioning, are recommended to penetrate the solution in the tissues of interest to be evaluated. In seeds of forest species, several preconditioning treatments have been used as cutting, scarification and soaking   The objective of the present study was to evaluate the viability of the seeds of M.
bimucronata by the tetrazolium test and to determine the crude oil content and the percentage composition of fatty acids.

Página | 1578
Harvesting and processing of seeds The fruits of M. bimucronata were harvested using aerial scissors with extensor cable, from eight matrix trees belonging to forest fragments located in the municipality of Garanhuns, Pernambuco, Brazil at 08º 53' 25" S and 36º 29' 34" W, at an average altitude of 896 m. According to the climatic classification of Köppen, the climate is type As, tropical climate with rainy season. The collection took place between the months of March and May of 2017, having, on average, the following climatic conditions: average temperature 23.2 °C, while the maximum and minimum did not exceed 28.9 and 22.2 °C, respectively and the accumulated rainfall was 182.1 mm during that period.

Tetrazolium test
For the tetrazolium test, the seeds of M. bimucronata were pre-moistened for 24 hours and then, with the aid of a scalpel, were cut longitudinally and medianly, the Classified as viable and unviable according to the standards indicated by Moore (1972), Delouche (1976) and Grabe (1976), for various agricultural and forest species: 1) viable: embryos completely colored light pink or bright red; end of radicle without milky white/yellowish staining and 2) non-viable: embryos completely with crimson red/red-intense or milky white/yellowish; radicle end of discolored or red-intense.
Results were expressed as percentage of viable seeds.

Tetrazolium
The results obtained for the percentage of viable seeds, the tetrazolium test at different concentrations and exposure times, and the standard germination test (control) to 30 °C are presented in Table 1.
It is observed that the mean of the viability of the seeds was higher in the staining period of 4 hours combined with the concentration of 0.075% of tetrazolium solution, differing statistically from the others. For the different concentrations, a decrease in the average of the viability of the seeds was observed as the concentration of the tetrazolium solution increased, with a significant effect for this factor. It was also verified that the average seed viability did not differ statistically from the results of the germination test (control -99%), for the concentration of 0.075% and time of 4 hours tested at that temperature. Means followed by the same letter (z, y), between germination (control -germination test) and viability obtained in the tetrazolium test, did not differ significantly at 5% probability by the Dunnett test.
In relation to the temperature of 35 ° C, the two-hour staining period provided the highest viability estimates in the 0.075 and 0.1% concentrations of the tetrazolium solution, not statistically different from each other (Table 2)

Composition and percentage of fatty acids
The profiles of methyl esters of fatty acids obtained from the seeds of M.