Productive, morphological and qualitative characteristics of sugarcane in the understory tree species in agroforestry systems

This study aimed to evaluate productive, morphological and qualitative characteristics of sugarcane in the understory tree species in two agroforestry systems. The study was conducted in the city of Frederico Westphalen, RS, in a randomized complete block design, characterized by a factorial arrangement of 2x5x3, that is, two agroforestry systems (strip and line), five tree species (angico, bracatinga, canafistula, eucalypt and guapuruvu) and three years of sugarcane cultivation (2009, 2010 and 2011), with three replications. The weight, length and stem diameter, number of nodes, Brix degree, juice volume, amount of sucrose, and how these factors are related to the interception of photosynthetically active solar radiation by the tree components in each system were evaluated. The interception of photosynthetically active solar radiation by tree components is smaller in the strip system, but increased over the years of sugarcane cultivation. Among the tree species, eucalypt is responsible for the highest values of interception. When grown in the understory of angico, bracatinga and canafistula, sugarcane presents greater length, diameter and stem weight, juice volume and amount of sucrose, mainly from the second cultivation year than when under the other tree species. The cultivation of sugarcane in the strip system resulted in an increased stem weight and juice volume from the second year of cultivation.   Key words: Saccharum officinarum L., solar radiation, shading, stem weight.