Análise da qualidade fisiológica de sementes de trigo tratadas com Tiametoxam através de técnicas óticas

Abstract

The practice of seed treatments with insecticides confers protection against early field pests, but evaluations are needed on the physiological and biochemical responses of crops subjected to these products. Standard tests (non-optical) are applied to evaluate the physiological quality of seeds. However, some tests can produce variable results. One of the alternatives found to assist traditional tests are through optical techniques, such as Ultra-Weak Photon Emission – UWPE and Fourier Transform Infrared Spectroscopy (FTIR). Thus, the main objective of this work is to compare the results of traditional techniques with those of optical techniques. Thus, it was used a sample of wheat seeds of the cultivar FPS Certero. The samples were divided into five groups: control group and groups treated with 75, 150 (recommended dose), 225 and 300 mL of the active ingredient Thiamethoxam (THX). The results of the optical tests were associated with first sand emergence count, sand emergence speed index, final sand emergence count, aerial part lengths, primary root lengths and dry mass. In sand emergence tests, final sand emergence count and sand emergence speed index obtained 90 % and 66 %, respectively, of simple correlation with photo-counts summation of the UWPEs trials. The results of the FTIR technique and the readings of the aerial part and primary root lengths and dry mass indicated no significant changes between the groups. In addition, it was used two samples with different vigor levels of the cultivar ORS Madrepérola. The optical techniques were the same as previously mentioned and it were read the aerial part lengths, primary root lengths and dry mass. The results indicated that traditional tests were not sensitive to observe the different levels of vigor. The FTIR results, through principal component analysis (PCA), indicated the different levels of vigor of the groups. Therefore, optical techniques can be used as auxiliary tools for the analysis of the physiological quality of seeds.