Determinação da temperatura base, desempenho agronômico e correlação de componentes de rendimento em genótipos de cana-de-açúcar

Abstract

The sugarcane has great social and economic importance in Rio Grande do Sul, Central Depression, however lacks research that allow to expand the cultivation and improve the quality of their products. This thesis -has order to give subsidy for the expansion and increased production of the culture of sugarcane in Rio Grande do Sul, with the use of better adapted genotypes. Two experiments were conducted in Santa Maria and Jaguari, both located in Rio Grande do Sul, Central Depression, in different crop cycles, from 2009 to 2013. We analyzed eight genotypes of cane sugar: RB855156, RB925211, RB925345, RB975932, RB867515, RB935744, RB925268 and RB987935. The base temperature of these genotypes by the method development was estimated relative, was evaluated sugarcane yield, quality variables (maturation index, total solids soluble fiber and volume of broth) and yield components (stems / metro numbers, length and stem diameter). The estimated base temperature values ranged from 7.5 to 12.8 °C in plant cane and from 7.4 to 10.8 °C in ratoon cane. The RB987935 and RB867515 genotypes showed greater productivity in all cycles of culture in Santa Maria and Jaguari. The sugarcane yield was higher than the national average, with the exception of RB855156 genotype of lowest productivity in Santa Maria, however presented higher yield in Jaguari. There was variation in the maturation index among genotypes and crop cycles and, considering this variable, the RB855156 genotype showed the highest precocity all cycles, also is among the genotypes with higher content of soluble solids along with RB925345 and RB925211. The fiber was variable over a maturation period between range and between growing cycles, with most values in the range from 9 to 12%. The volume of broth per ton of cane ranged 215-351, 221-493, 305-587 l t-1, in the cycles of plant cane, cane ratoon cane first and second ratoon respectively. The variable number of stems / meter showed the highest correlation with sugarcane yield, it is important to review the selection indirectly for genotypes more productive.