The objectives of this study were to perform the physicochemical characterization of chitosan, to evaluate its effects on germination, early growth, root anatomy and on the cell cycle of two maize hybrids. The hybrids DKB 390 and DKB 390 VTPRO (transgenic) were used. DKB390 VTPRO is from Monsanto, and the event number is 89034, which expresses the proteins Cry1A105 and Cry2AB2. For the physico-chemical characterization of chitosan, the following analyzes were performed:, elemental analysis, total ash, infrared absorption spectroscopy, nuclear magnetic resonance, powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and viscosity. With the analysis of infrared absorption spectroscopy, nuclear magnetic resonance, powder X-ray diffraction, thermogravimetric and elemental analysis it was observed that the structure of chitosan presents a low level of deacetylation. Chitosan had a total ash value of 1.32% and high viscosity. By scanning electron microscopy the chitosan was classified as porous and fibrous structure. Increase in the seed germination rate was observed in both maize hybrids in the presence of chitosan, without changes in the initial growth. The cell analyzes showed that the chitosan was not toxic even at high concentrations, since the mitotic index remained unchanged and no chromosomal abnormalities were detected. The effects of chitosan in root anatomy were evaluated through the measurements of sections of root tips on histological preparations, and the genetically modified hybrid presented the best results. As conclusion, the use of chitosan in appropriate concentrations may favor the development of maize (especially transgenic) acting on germination or changing the root anatomy and consequently increasing resistance and adaptation of the seedlings to adverse conditions.

It is a fact that the regions that cultivate the most maize crop do not have fully adequate technologies to measure productivity losses caused by irregularities in water availability. The objective of this study was to evaluate the physiological characteristics of maize hybrids tolerant (DKB 390) and sensitive (BRS 1030) to drought, at V5 growth stage and under water restriction, in order to understand the mechanisms involved in the induction of tolerance to drought by chitosan in contrasting maize genotypes. Plants were cultivated in pots at a greenhouse, and chitosan 100 ppm was applied by leaf spraying. The water restriction was imposed for 10 days and then leaf gaseous exchange and chlorophyll fluorescence were evaluated. The tolerant hybrid (DKB 390) showed higher photosynthesis, stomatal conductance, carboxylation efficiency, electron transport rate, and non-photochemical quenching when chitosan was used. Plants from tolerant genotype treated with chitosan were more tolerant to water stress because there were more responsive to the biopolymer.

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