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Selenium (Se) deficiency in the human population is one of the major nutritional problems in the world. A possible solution is biofortification. Biofortification is a process that increases the ele...

The rice is a grain which belongs to the Poaceae family. It is produced in two ecosystems wich are the floodplain and the uplands. It is used as part of the daily diet of diferent populations. There is a growing demand for rice consumption around the world. That cereal has great socioeconomic importance. The State of Tocantins has a great productive potential. Therefore, the aim of the study was to evaluate the productive performance of upland rice cultivars in five years of evaluation in the cerrado of the southern state part of Tocantins. The experiments were conducted on the field at the Chaparral Farm and on the Experimental Station of the Federal University of Tocantins in the years of 2007/2008, 2008/2009, 2009/2010, 2010/2011 and 2011/2012. The experimental design was a randomized blocks with four replications in a 4 x 5 factorial scheme, consisting of four genotypes and five years. The evaluated characteristics were number of days to flowering, plant height, weight of hundred grains and grain yield. It was concluded that the 2007/08 crop year was where the cultivars presented the highest grain yields ranging from 2729 to 1716 kg ha -1 . The cultivars BRS-Bonanca, BRS-Primavera and BRSMG-Conai reached the best averages of grain production on the five years of cultivation. Those cultivars can be indicated for use in the region. It is suggested that more studies have to be carry out on different planting periods for upland rice in Tocantins.

Behavioural assessment of cultivars adapted to climate and soil variations is essential for recommending genetic materials to producers, achieving higher profitability, and, mainly, targeting regional growth. The aim of this study was to evaluate the agronomic performance of upland rice cultivars in different cropping periods and Cerrado vegetation soil in the southern region of the state of Tocantins. The experiments were conducted in a field at the Chaparral Farm and at the Experimental Station of the Federal University of Tocantins in the agricultural years of 2008/2009, 2009/2010, 2010/2011, 2011/2012, and 2012/2013 with cultivars BRS-Bonança, BRS-Primavera, and BRSMG-Conai. A randomized block experimental design was used with four replications in a factorial scheme of 3 × 5, comprising three genotypes and five years. The evaluated characteristics were as follows: number of days to flowering, plant height, weight of hundred grains, and grain yield. The highest upland rice yield was observed in the cropping period of 2012/13, which also had the highest volume and better distribution of rainfall; flowering time was lesser and greater for BRSMG-Conai and BRS-Bonança cultivars, respectively. The BRS-Primavera cultivar showed the highest grain yield in different years in Cerrado soil in the southern region of the state of Tocantins.