Qualidade fisiológica e pré-condicionamento de sementes de cultivares de soja de diferentes grupos de maturidade em três épocas de colheita / Physiologic quality and pre-conditioning of soybean seeds cultivars with different maturity groups in three harvesting times

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The use of quality seeds in soybean plantations is fundamental to guarantee fast and appropriate establishment of the stand. The objective of this work was to evaluate the physiologic quality of soybean seeds harvested in three times and submitted to the osmotic conditioning. Seeds of the soybean cultivars with different maturity groups: Confiança (semi-precocious), UFV-16 (medium), Splendor (medium), Warranty (semi-late), UFVS 2005 (semi-late) and UFV-18 (late) were multiplied in the Experimental Field Prof. Diogo Alves de Mello of the Department of Fitotecnia of the Federal University of Viçosa in an experimental design in casualized blocks with four replications. Harvesting of plants of each cultivar was done at the R8 stage and at 15 and 30 days after this stage. Seed samples of each cultivar, per crop time and replication, were submitted to the osmotic conditioning in a polyethylene glycol solution (PEG 6000) with osmotic potential fitted at -0,8 MPa with 0.2% of the Captan fungicide at the temperature of 20 C during 96 hours. Non conditioned seeds were used in the control. The curves of soaking of non conditioned seeds in water and in the PEG 6000 solution were evaluated. Their viability and energy were evaluated with the tetrazoil test; and the germination and energy of seeds with the following tests: germination (first counting - PC and final counting - TG), emergency speed of seedlings in the field and in sand bed, emergency of seedlings in the field and in sand bed and electric conductivity. The soaking speed and humidity of seeds of the six soybean cultivars in the PEG 6000 solution of the three harvesting times were lower than with distilled water. The cultivars presented differences between them and behavior with harvesting retardation with reduced germination and energy of seeds. The osmotic conditioning with PEG 6000 solution improved physiologic quality of seeds obtained in all harvesting times, mainly at the time R8+30 days which had larger deterioration degree. These tests can be promising to increase germination and to evaluate energy of seeds damaged by humidity. The classes 1 and 2 and their sums were coherent with the energy (1 to 3), viability (1 to 5) and percentage of seed germination based on the tetrazoil test. The sum of classes 1 and 2 and the evaluation of energy by the sum of classes 1 to 3 with tetrazoil test can constitute additional information to interpret seed energy. All characters studied were correlated between themselves.

ASSUNTO(S)

soja retardamento de colheita condicionamento osmótico soybean osmotic conditioning seeds fitotecnia

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