Selecting Sorghum Forages for Limited and Full Irrigation and Rainfed Conditions in Semiarid, Subtropical Environments

Sorghum (Sorghum bicolor L.) forage producers in semiarid regions must maximize yield with reduced irrigation. Dry matter yields of furrow-irrigated sorghum forage [conventional and photoperiod-sensitive sorghum-sudangrass (Sorghum bicolor var Sudanese) hybrids (SS and PS, respectively) and forage sorghum (FS)] managed for hay in cultivar evaluations (randomized complete blocks with four replications) were compared from two years each of full irrigation (FULL: 4 furrow irrigations/year, applying approximately 6 inches each; two harvests), limited irrigation (LIM: 2 furrow irrigations/year, applying approximately 6 inches each; two harvests), and no irrigation (NONE: one harvest). Significant (P < 0.05) sorghum forage type comparisons for annual yield were observed within FULL and LIM because SS outyielded FS when irrigated, with PS being intermediate (4.54 vs. 5.62 tons/acre for FS and SS within FULL, respectively, and 4.17, 5.04, and 5.38 tons/acre for FS, PS, and SS within LIM, respectively). Within NONE, PS outyielded SS, and FS was intermediate (1.59, 1.75, and 1.28 tons/acre for FS, PS, and SS within NONE, respectively). Seasonal precipitation distribution likely impacted yields. Results indicate that SS or PS hybrids are best for hay production when irrigation water is available and that FS and PS hybrids are better than conventional SS hybrids under rainfed conditions.