Curva cinética de carboidratos de grãos de milho verde cultivado sob adubação nitrogenada e potássica

Abstract

After nitrogen, potassium is the element absorbed in greater quantities by the maize crop, with an average of 30% being exported to the grains. In the production of hybrid maize cultivars for harvest in the green stage, it is desired, among other factors, the permanence of the harvesting point of the spikes for a longer period and balance between sugar and starch contents, so that the grains retain their flavor characteristics sweet and tender. Therefore, this work aimed to study the kinetics of carbohydrates of maize grains grown under potassium and nitrogen fertilization. The sample used to obtain the glucose and starch kinetic curve was composed of green corn kernels collected from 5 ears harvested in the first hours of the morning from an experimental culture using three different doses of nitrogen and potassium fertilization. The ears were stored in plastic bags with identification corresponding to the original treatment and were taken to the Laboratory of Technology of Agricultural Products (LTPA) of the Department of Soils and Rural Engineering of the Center of Agricultural Sciences (CCA) of the UFPB. In the analyzed treatments the humidity at the time of harvest ranged from 91.31 to 26.52%, which reveals a great reduction of moisture in the grain within the evaluated time (64.79%). The results also indicate that the harvest of corn at 72 days of cultivation for the T1 is the ideal when it is desired to obtain green corn, since it was the period in which the grains presented their highest glucose index. While for T2 and T3 treatments, the ideal harvest time was at 85 days of cultivation, when 3.07 and 3.10% of glucose were obtained, respectively. It can be observed that there was a linear increase of the starch contents in all treatments within the time of evaluation, and it is worth mentioning that the starch deposition increased with the evolution of the maturation, so that the reactions of sugar transformations could be observed . It can be concluded that the kinetics of the conversion of glucose to starch in the green maize AG 1051 was not influenced by nitrogen and potassium fertilization. The study also demonstrated total conversion of glucose (reducing sugar) to starch, during the 128 days of cultivation.