Cultura de embriões e germinação de sementes de diferentes níveis de qualidade para a produção de mudas de café

Abstract

The quality of coffee seeds is influenced by several factors, such as post-harvesting operations of drying, processing and storage that can cause damages to the plant tissue. In recent research, it has been confirmed that the endosperm is more sensitive to the deterioration process than the embryo, which can germinate and produce a normal seedling, when isolated from the seed. The use of antioxidants can improve the performance of seeds subjected to stresses by removing free radicals present in the damaged seeds. In this context, the studies were carried out with the aim of investigating the formation of coffee seedlings from seeds with low levels of quality. It was used seeds of different quality levels of Coffea arabica L., Catuaí amarelo IAC 62, obtained from freshly harvested seeds and submitted to aging for four days. In the first study, the whole and fractionated seeds were immersed in cathodic water, ascorbic acid, distilled water and one part was evaluated without imbibition. The germination test was carried out, in which was evaluated the percentage of root protrusion, normal seedlings and expanded cotyledon leaves. Simultaneously the emergence test and growth evaluations of the seedlings, by means of the stem diameter, hypocotyl length and dry weight were evaluated. Fractionated coffee seeds have worse physiological performance than whole seeds, mainly the lower quality seeds. The effect of the antioxidant treatment on the physiological performance of the seeds was variable with the fractionation and quality level. In the second study, coffee embryos were cultured in vitro using different quality levels obtained by the same way. For the imbibition of the seeds it was used boric acid and distilled water and the embryos extracted were treated with cathodic water, ascorbic acid and distilled water. It was counted leaf and root presence at 15 days, germination at 30 days and hypocotyl and root size were measured at 120 days. The addition of boric acid in seed imbibition water provides more vigorous seedlings after embryo culture and does not require the use of antioxidant treatment. In the absence of boric acid in seed imbibition water, the use of cathodic water improves the physiological performance of the embryos. The use of ascorbic acid may benefit the physiological performance of seeds, but is harmful to the culture of embryos. It is possible to form coffee seedlings from the cultivation of embryos extracted from low quality seeds.