Recuperação e germinação de sementes de Echinochloa spp., Eragrostis plana e Oryza sativa em épocas e profundidades no solo

Abstract

Aiming the continuous use of areas for agricultural purposes, it is important to understand the seed viability and persistence in the soil of the weed plants that impact the agricultural economy of the Rio Grande do Sul state, such as Echinochloa spp., Eragrostis plana and Oryza sativa. In this way, the objective of this study was to evaluate the recuperation and germination rate from the weed species Echinochloa spp., E. plana and Oryza sativa, and from the crop Oryza sativa, allocated in soil depths and after three and six months of storage time. The experiment was conducted in the experimental area of the Univerdade Federal do Pampa – UNIPAMPA, Itaqui Campus-RS. The experimental design was completely randomized with a three-factorial scheme, each one with four repetitions. The treatments were: A) depths of seed allocation in the soil: 0, 5, 10, 15 e 20 cm under the soil surface; B) Two collect periods to assess viability: 3 (dez/2016) and 6 (mar/2017) months after the deposition; C) four plant species: Echinochloa spp., Eragrostis plana, Oryza sativa (weed plant, red rice) and Oryza sativa (commercial crop, Puitá cultivar). The following variables were evaluated: number of seeds recovered and germination of the recovered seeds (%). For the statistical analyzes of the quantity of recovered seeds, the analysis of variance was performed by Fischer's DMS mean test (p≤0.05). The germination data that did not fit to the normal distribution was transformed to the square root. Regardless the depth, the commercial cultivar did not show germination after six months buried in the soil. The Eragrostis plana species showed greater seed conservation in the soil when compared to the other species, independent of the collect period, from 5 cm below the soil. Through the results found in this study, it is recommended the minimum amount possible of tillage operations in areas with infestations of these three weed species because these operations assist the insertion of these seeds in the soil, thus increasing the seed bank in the soil. It was concluded with this study that the greater the depth, the higher the values of apparently viable seeds for the weeds will be.