Efeito da superação da dormência no armazenamento de sementes e sintomas de deficiência nutricional em mudas de Acacia mearnsii (De Wild.)

Abstract

This study aimed to understand the evaluate the effect of nutritional deficiencies in seedlings of Acacia mearnsii and the influence of breaking dormancy in seed conservation of that specie through laboratory storage. In the first article, we attempted to a relationship between the presence of physical dormancy and maintaining the longevity of acacia seeds. The initial batch was separated as follows: in part of seeds, the dormancy was broken with sulfuric acid for 50 minutes, and then washing the seeds in tap water was taken, and another part of seeds remained dormant. Subsequently, the two batches, with and without overcome dormancy were stored in sealed plastic containers polyethylene in cold room conditions (12 ° C ± 2 ° C) and laboratory ambient (20 - 34 ° C). After 3, 6 and 9 months of storage seeds were evaluated as to physiological quality by the germination test, moisture, seedling length, electrical conductivity and accelerated aging. Unlike in cold room conditions storage, there were losses of germination potential seeds to overcome dormancy. There was reduction of seed vigor, expressed by accelerated aging test for all treatments. The moisture content of the seeds during storage remained constant, except when compared with seeds and without overcome dormancy, the first with higher averages. There was also an increase in electrical conductivity in all treatments from the sixth month of storage, showing decrease of seed vigor, following the behavior observed in the germination test. It follows that the impermeability cutaneous is related to maintaining seed viability in storage, and the absence the dormancy has negatively influence and germination and vigor of stored seed. In the second article, the visual symptoms of nutrient deficiency were characterized in Acacia mearnsii seedlings and evaluated the growth, biomass production and nutrient accumulation in shoots of seedlings Acacia mearnsii in the absence of macro and micronutrients by the missing element technique in nutrient solution. The treatments consisted of thirteen nutrient solutions: complete solution (SC), SCN, SC-P, SC-K, SC Ca, Mg-SC, SC-S, SC-Mn, SC, Mo, Zn-SC , Fe-SC, SC-B, SC-Cu. All treatments showed symptoms of nutritional deficiency. The decrease of production was manifested in the following order: Ca=B =N=Fe < Zn<K<Mg=Cu<P=S<Mn=Completo.