Alterações fisiológicas e bioquímicas em sementes de milho submetidas a diferentes tratamentos químicos e armazenamento

Abstract

The chemical treatment of maize seeds is a widely adopted practice for the protection of crops in early stage. However, some molecules have interfered in the quality of seeds, especially those stored, accelerating their deterioration. The objective of this work was to investigate the influence of insecticide treatments on the enzymatic expression and quality of maize seeds submitted to storage, determining which enzymatic systems may be affected in a possible phytotoxic action of the products. Seeds of the 2B647PW and SHS4070 hybrids were treated with four different chemical treatments (standard treatment, standard + clothianidin, standard + thiamethoxam and standard + fipronil) and stored for different periods (0, 3, 6 and 9 months). The physiological quality tests performed were germination first counting, germination, cold test and emergence. The analysis of the expression of α-amylase, esterase, superoxide dismutase, catalase and malate dehydrogenase and alcohol dehydrogenase enzymes was performed by the gel electrophoresis technique. Reductions in the first germination and emergence counts were observed for the two hybrids studied over the storage period. Thiamethoxam seed treatments led to a greater reduction in the physiological quality of the seeds of the 2B647PW hybrid during the study period. In general, there was a reduction of the enzymatic expression in the seeds at nine months of storage. The enzymatic analyzes are a more sensitive practice for detecting the state of seed deterioration. It is concluded that the quality of maize seeds treated with insecticides and stored varies according to the product used, storage period and hybrid. The treatment with the insecticides clothianidin, thiamethoxam and fipronil reduces the physiological quality of the seeds of hybrid 2B647PW at nine months of storage. The treatment of seeds with the insecticides clothianidin, thiamethoxam and fipronil reduces the expression of the α-amylase, superoxide dismutase and catalase enzymes at nine months of storage. The enzymes α-amylase, superoxide dismutase, catalase and alcohol dehydrogenase are good markers of the quality of hybrid corn seeds.