Biometric and chemical characteristics of sugarcane varieties for use as forage in limiting soil water conditions

This study aimed to evaluate the biometric and chemical characteristics of five sugarcane varieties (RB 863129, RB 867515, RB 92579, RB 943365, and RB 98710) grown in a semi-arid climate for use as forage. The experiment was designed as randomized blocks, in a 5 x 2 factorial arrangement (five sugarcane varieties and two evaluation times, 407 and 483 days). Response variables included dry matter productivity, morphological characteristics, chemical composition, digestibility, and ratios among neutral detergent fiber (NDF), Brix, and Pol. For the biometric analyses, there was an interaction effect between the evaluated varieties and harvest times on the variables fresh matter yield, uncovered internodes, and stalk density (MID - middle internode density). Regarding stalk density (MID), at 407 days, there was no significant difference among the varieties (1.19 g cm(-3)). For the fractionated parts, there was an effect of harvest time on the amount of fresh matter and dry matter of tops produced, which was highest at 407 days of age. A significant difference was detected among the varieties for contents of dry matter and total digestible nutrients. The variable in vitro neutral detergent fiber digestibility was influenced by the time, decreasing by 53.62 g kg(-1) at 483 days. In the analysis of Brix and Pol yields per hectare, it was observed that variables ton of Brix per hectare and ton of sucrose per hectare averaged 15.12 and 10.14 t ha(-1), respectively, and the NDF: Brix and NDF: Pol ratios were higher for variety RB 863129, with 2.93 and 3.68, respectively. Variety RB 867515 is suggested for forage production in semi-arid conditions, as it is best adapted to the local soil-climatic conditions and to the water deficit, especially at 407 days.