Desempenho de cultivares de milho pipoca no estado de Goiás

Abstract

The state of Goiás stands out as the third largest national producer of corn, however, the production of popcorn is still very incipient and, most of the agricultural areas of the state, are destined for the production of common corn. However, the few producers who seek to insert popcorn production in their areas are hampered by the lack of information on cultivars available on the market, the proper management of the crop and the technical recommendations. Therefore, the objectives of the present study were to evaluate the agronomic performance of three popcorn corn cultivars, in the Northeast of Goiás, in the dry season and under irrigation system; and to evaluate the agronomic and physiological performance of three popcorn cultivars in Southeast Goiás, during the water harvest. Two experiments were conducted and evaluated. Experiment I was conducted at farm II of the State University of Goiás - UEG, Campus Nordeste, in the Posse unit, under a sprinkler irrigation system, during the dry season (April - July). During the conduct of this experiment, variables related to plant growth and development and the percentage of plants that showed symptoms of red and pale corn stunt were observed, in order to evaluate the agronomic performance of the cultivars. Experiment II, on the other hand, was carried out in the experimental area of the State University of Goiás, Campus Sudeste, Ipameri Unit, without irrigation system, during the water harvest (Nov. - March). The variables related to the vegetative and reproductive stages of the plants, the percentage of plants showing symptoms of red and pale corn stunt, and the physiological variables related to the performance of the photosynthetic machinery of the plants were evaluated. In both experiments, the components of variance (CVg, IV, h2 ) and genetic diversity were estimated. The experiments were conducted in the field, using a randomized block design (DBC), with three cultivars (‘Americana’, ‘UENF-14’, variedade Formosa) and four replicates. Each experimental plot consisted of four lines, 4 m long, with a spacing of 0.90 m between lines and 0.25 m between plants. The experimental data were subjected to individual analysis of variance with the respective developments and averages test. In experiment I, there was a significant difference for final stand, final plant height, ear insertion height, productivity and percentage of plants with red corn stunt symptoms. The cultivar UENF-14 showed the lowest percentage of symptom of Phytoplasm and the highest productivity, while the Formosa variety was more susceptible to red corn stunt, presented the smallest final plant stand and low productivity. The cultivar ‘UENF-14’ was the one with the highest total productivity (2.325,83 t ha-1 ), differing from the others. In experiment II, the cultivars showed significant differences for all agronomic, phytopathological and physiological variables, except for the variables initial stand (EI), stem diameter (DC), percentage of bedridden plants (PA) and minimum fluorescence adapted to light (Fo '). The variety Formosa showed the lowest productivity, around 361 kg ha-1 , followed by the cultivar Americana, which presented intermediate values of 781,5 kg ha-1 , and finally, the 'UENF-14' with productivity total of 2.074,23 kg ha-1 . The reflection of the damage caused to the plant structure by the molicutes (Spiroplasma kunkelli and Phytoplasm) and the environment itself reflected in the photochemical efficiency of the PSII, which may have compromised the effective availability of NADP and ATP, which evidenced the cultivar UENF-14, as the cultivar that suffered less damage to the leaf structure. The estimation of the genetic parameters allowed to verify the effects of the interaction between cultivars x significant environments for most of the evaluated characteristics (AFP, IEA, PA, PP, PEN1, PEN2, R1, EFZP, EPP, CPE, PROD), so the cultivars showeddiffent performance in different environments. The heritability of the productivity characteristics were of high magnitude (> 83,73%). The average yield of cultivars was 1305.37 kg ha-1 . The variables that contributed to the genetic divergence between the cultivars, when they were grown in Posse-GO, were number of ears per plot (66,32%) and Productivity (33,68%), both contributed to 100% of the existing divergence. In Ipamerí - GO, the variables that contributed most to the divergence between the three cultivars were ear insertion height (48,58%), productivity (31,72%) and number of ears per plot (14,79%), both contributed 95,05% to the existing divergence. The results allow us to infer that the Formosa variety probably originates from successive seed salvages of the Americana cultivar and that there is genetic divergence between UENF 14. In summary, it is concluded that the cultivar UENF 14 presented the best performance