Early selection of sugarcane using path analysis.
The aim of this study was to analyze sugarcane (Saccharum officinarum) biometric and technological data, obtained at different timepoints, using path analysis. The experiment was conducted in União, PI, Brazil, and evaluated 12 sugarcane genotypes (RB036066, RB9438, RB935744, RB021764, RB021754, RB021534, RB966229, RB977540, RB863129, and RB987935, and the varieties RB92579 and RB867515 as controls) in a randomized block design with four replications. Data were collected at six timepoints that were spaced 30 days apart (90, 120, 150, 180, 210, and 240 days). Direct and indirect effects of the following production components were compared: stalk length, stalk diameter, internode length, number of tillers, number of green leaves, and stalk dry matter. The technological variables evaluated were total recoverable sugar, degrees Brix, tons of polarization (pol, apparent sucrose content) per hectare, juice purity, fiber, juice pol, and tons of sugarcane per hectare. The coefficients of determination were high in all path analyses, suggesting that the components evaluated explained a large part of the variation in stalk production and in the technological variables. Stalk diameter was the trait that best correlated with stalk dry matter yield at all timepoints, with positive values that were higher than the residual effect. This demonstrates the possibility of obtaining significant gains via indirect selection for stalk dry matter yield via stalk diameter or via stalk diameter and number of tillers. The technological variables degrees brix and juice pol were the traits that best correlated with total recoverable sugar production, indicating that they could be used to indirectly select for total recoverable sugar.