Caracterização de genótipos crioulos de cana-de-açúcar

Abstract

Brazil is world’s largest producer of sugar cane, and in the state of Rio Grande do Sul its cultivation is associated with activities in small properties,so related to livestock and processing of products such as molasses, “rapadura” (candy of the juice of sugar cane), brown sugar and rum. The expansion of sugar cane cultivation in the state of RS is promising. However, but studies with crop breeding are scarce in the region, the farmers use genotypes introduced at the beginning of the eighteenth century, and from other regions of Brazil and abroad in recent decades. Many of these genotypes already have great adaptation to temperate region. This fact makes them an excellent basis for the breeding program of cane sugar, aiming at its development in this region. The objective of this work was genetic variability characterize 187 landrace genotypes of sugar cane collected in Rio Gande do Sul e Santa Catarina. The experiment was conducted at Embrapa Clima Temperado, Pelotas, RS during the 2012/2013 to 2013/2014 seasons. The following characteristics were evaluated, number of stems per meter; number of stems per plant; total soluble solids (°Brix); stem diameter; stems per ha-1; ton Brix per ha-1; weight of ten stalks; type of straw removal; presence of ´joçal´ (leave pilosity); presence of cracks; plant height; stem diameter; general score; growth habit; dry mass; neutral detergent fiber; acid detergent fiber; crude protein; ashes; in vitro digestibility of dry mass; hemicelluloses and lignin. The evaluations of disease resistance, maturation, and cold resistance were also realized. The variables were analyzed using descriptive and multivariate statistics. The genotypes showed variability for all the features, enough to be used aiming a germplasm bank formation, as well as for further breeding work. Regarding the cold tolerance, most genotypes showed low damage levels. As for diseases, most genotypes have good and high resistance to brown rust and brown spot, although there are few susceptible genotypes. Regarding the maturation, a group of 10% of the genotypes showed early maturity behavior, and 23% mid maturity, and 67% late maturity. Genotypes with productive potential were identified and they may be indicated for direct use by producers.