Aplicação da quitosana em milho transgênico e não transgênico

Abstract

This study aimed to collaborate with surrounding studies of maize crop by physicochemical characterization of chitosan and evaluation of its effects on the germination and early growth, cell cycle and root anatomy in two corn hybrids. The characterization was carried out by methods such as absorption spectroscopy in the infrared region, percentage of deacetylation, determination of total ash, diffraction of x-ray, scanning electron microscopy and viscosity analysis. To evaluate its effects, transgenic corn hybrids were used and not transgenic, exposed to 7 chitosan treatments dissolved in acetic acid 0.1%. Petri dishes lined with two sheets of filter paper and moistened with 3.6 ml of the respective treatments were maintained in germination chamber type B.O.D., with temperature of 25 ° C and photoperiod of 12 hours. The experiment consisted of seven treatments (control, 50, 150, 300, 600, 1200 and 2400 ppm), with 4 replications of 15 seeds per plate. Its effects on germination were evaluated by the germination percentage (G%) with 48 hours of exposure to treatment and germination speed index for 7 days 12 to 12 hours. To evaluate the effects on early growth were measured root length and relative water content. To measure their effects on the cell cycle, we evaluated the mitotic index and the presence of chromosomal abnormalities with root tips collected after 96 hours of exposure to the respective treatments. The effects of chitosan in the root anatomy were evaluated 7 days after treatment by collecting root tips, preparation of microscope slides and root structures of primary measurements. The statistical analysis was performed by analysis of variance (ANOVA) and mean comparison test Skott-Knott, 0.05% significance (p≤0.05) in Sisvar version 4.3 program. The structure of chitosan used in this study have been characterized with others in the literature and the biopolymer has increased viscosity according to the concentration. The percentage of deacetylation was found in medium / low grade, justifying the ash content found as superior to that found in the literature, but within the commercial standards. In both hybrids can be observed an increase in G% when in contact with high concentrations of biopolymer, unlike shown in the initial growth, where there was a decrease of the evaluated parameters, except the root length of DKB 390 Pro, which has not changed. The mitotic index DKB 390 when exposed to decreased concentrations of chitosan, unlike the GE, which remains unchanged exposed to low concentrations. The low frequency of chromosomal abnormalities indicates that the biopolymer is not genotoxic in the studied concentrations. The effects on root anatomy of hybrids were different, with better results for the DKB 390 Pro as the best hydraulic conductivity and greater protection against unwanted substances. It is concluded that chitosan in suitable concentrations can provide good developing maize (especially in transgenic) during germination as for changes in root anatomy, allowing for greater resistance and adaptation to the adverse conditions of the seedlings.