Tratamentos hormonais em sementes de hortaliças tuberosas.

Abstract

The use of growth regulators as seed treatment increases every year, to stimulate germination and / or seedling development, however the costs to purchase these inputs are quite high precluding their use in certain agricultural sectors. An alternative to minimize production costs would be the benefit of allelopathic principles of certain substances in certain parts of plants, such as the use of extracts obtained from sedge (Cyperus rotundus L.), which some studies indicate present in your constitution the presence of growth-stimulating substances such as the presence of natural auxins. Thus, the objective is to evaluate the effect of the sources of natural auxin extract (nutsedge) and synthetic (indole-3-butyric acid, IBA) on the germination and early seedling development of carrot, beet and radish. In the present study two experiments, both studies employed a completely randomized design with four replications of 25 seeds per treatment and 20 seeds for germination primary root length were conducted. In Experiment I, the seeds of carrots, beets and radishes were submitted four concentrations of 0,0, 0,5, 1,0, 1,5 mg L-1 IBA (synthetic auxin). In Experiment II, the seeds of the studied species were treated with concentrations of 0, 15, 25, 50 and 100% of the aqueous extract of C. rotundus (natural source of auxin), facing the best of the synthetic auxin concentration obtained for each species in experiment I. In both experiments, for the purpose of the treatment, the seeds were soaked in each solution for five minutes. Seeds were sown on two sheets of paper germitest, which were arranged in the form of rolls, wrapped in plastic bags to the root length, and about two sheets of blotting paper placed in box gerbox for the germination test, and the substrate moistened with distilled water amount equivalent to 2,5 times its dry weight and maintained in a growth chamber set at recommended for each species at both test temperatures. Evaluations consisted of germination, first count, index of germination rate and radicle. Data were subjected to analysis of variance, means were compared by Tukey test at 5% probability and polynomial regression. It was observed that the best concentrations of the synthetic auxin for carrot and radish were 1,0 and 1,5 mg L-1, respectively, for beet seed no significant difference between the concentrations compared to the control. There was no effect of the extract of nutsedge germination of carrot seeds. The use of the aqueous extract of C. rotundus in 100% concentration during seed soaking beet, favors the early development of seedlings raising the speed of germination and causing protrusion and further development of the taproot, when compared to the use of synthetic auxin . The aqueous extract of C. rotundus promoted the increase in speed of germination and early seedling development when their radish seeds are soaked with concentrations around 25%, similar to the results obtained when employing synthetic auxin.