Abstract

This study aimed to evaluate the effect of different irrigation depths and harvest dates in sweet potato for conversion to biofuels. Irrigation treatments were 0.25, 0.50, 0.75, and 1.0 of crop evapotranspiration rates and a control treatment (without irrigation). Harvest dates were: 90, 120, 150, 180, and 210 days after planting (DAP). The sweet potato cultivar BRS Cuia (RNC-27.315) was utilized. The experimental design was a randomized block in factorial arrangement (irrigation depths combined with harvest dates) with four replications. Reference crop evaporation was calculated based on the method of FAO Penman-Monteith. Drip irrigation system was used and irrigation frequency was every seven days. The highest and lowest yield were at 90 and 210 DAP, respectively. The lowest yield variation was between 120 and 150 DAP. Control treatment had highest yield in all harvest dates. Efficient water use was greater with irrigation of 0.25 of ETc with 116.9 and 218.8 m³ ha at 90 and 210 DAP, respectively. Starch content, crude protein, length and diameter of the root, and yield were influenced by different irrigation depths and harvest dates.

Key words: Ipomoea batatas, irrigation management, ethanol feedstock, drip irrigation, water deficit, efficient irrigation strategies.