Tratamentos para a quebra de dormência em sementes de Lolium multiflorum Lam. armazenadas e recém colhidas

Abstract

The ryegrass (Lolium multiflorum Lam.) is an annual Poacea of great importance, especially for the southern region of Brazil, can be used for the production of forage and green cover in no-till systems, but when ripens its seeds fall to the ground and remain dormant until the early fall when they have ideal conditions for germination, thus having the phenomenon known as dormancy. For ranchers phenomenon of dormancy may be found useful, since it allows a natural and reseeding distributed over time. On the other hand, for the seed producer, dormancy is a problem because it alters the germination, preventing the determination of the physiological quality of the seeds accurately. Thus becoming necessary techniques and substances that can break this dormancy. This work it was aimed to evaluate the efficiency of dormancy breaking through different treatments: control, gibberellic acid at 0.05%, gibberellic acid at 0.1%, gibberellic acid at 0.5% potassium nitrate at a concentration of 0.2% potassium nitrate at a concentration of 0.5% and pre-cooling treatment at 5 ° C for seven days, in two batches of ryegrass seed, a recently gathered and one stored for a long period. After the performance of different treatments, the following parameters were analyzed: germination rate, germination, emergency, emergency speed index, tetrazolium and dry matter, after the data were subjected to statistical analysis of mean tests and ANOVA with Tukey. Results were obtained as: The use of GA3 at a concentration of 0.1%, is the most effective treatment for overcoming ryegrass dormancy. Treatments for breaking dormancy in seeds harvested just used in this study are inefficient since no treatment enables the minimum germination of seed for marketing 70%, is achieved. The use of KNO3 at a concentration of 0.5% decreases the germination and emergence of ryegrass seeds.