Desempenho agronômico e análise energética de variedades crioulas e híbridos cultivados em diferentes sistemas tecnológicos de manejo

Abstract

The landraces varieties promote the autonomy and the control of the production process for family farmers. However, there has been observed the abandon of these varieties by these farmers to raise the level of technology applied in farming. In addition, as in this segment of agriculture as in the non-familiar segment, corn is grown under different production systems with different energy efficiency indicators. Thus, the aim of this research was to investigate the influence of different technology systems of management on agronomic traits of corn, and it was to analyze this systems under the energetic point of view. We used two landraces varieties (Argentino and BR da Várzea), a double hybrid cultivate SHS 4080 and a simple hybrid cultivate IAC 8333. The statistical delineation was randomized blocks in factorial scheme 4x3 (four genotypes of corn and three systems of management) in bands, with three repetitions. The management systems were classified as low, medium and high technological level. We used five performance indicators: energy efficiency, liquid cultural energy, cultural efficiency, energy balance and productive energy efficiency. In general, the landraces varieties were able to respond the improved technology, as much as modern cultivars. Management practices available, as the use of organic manure and the application of homemade to the pest control, they are able to maximize production of corn. The landraces varieties BR da Várzea is a promising material for expressing its productive potential in management systems at low, medium and high technology levels, setting behavior similar to that presented by the double hybrid SHS 4080 and by the simple hybrid IAC 8333. it was dominated the direct energy and sowing operation had the highest energy expenditure. Under high technological level, on the other hand, it was predominant the indirect energy and the operation of the largest expenditure was the covering manures. From the perspective of family farming, it was verified the largest social importance of the systems under low and medium levels of technology, due to the increase employment capacity of rural labor. The liquid cultural energy and energy balance were more favorable for the system under high technological level. Though, the cultural efficiency for medium and low technological levels was significantly higher. The average of energy efficiency of the system under medium technological level exceeds 10 times the average obtained by the system at high technological level, not being possible to calculate to the low technological level, due to the lack of fossil energy in this treatment. The systems under low and medium levels of technology presented productive energy efficiency, being of 5.38 and of 5.39 kg MJ-1, respectively. Under high technology level, productive energy efficiency was only 0.45 kg MJ-1. Regarding the genotypes, the landrace variety BR da Várzea presented the potential to generate energy as much as the hybrids. In general, the biggest sustainability in the corn crop was achieved, when it was used the management system under medium and lower level of technology under the high technological level.