Effect of Graded Mechanical Shock Pulses from a Shock Tube on Germination, Growth, and Antioxidant Enzyme Activities in Sweet Sorghum (Sorghum bicolor L. CSH 16)

Sweet sorghum (Sorghum bicolor L. Moench CSH 16) supports food, feed, and biofuel production in arid regions, but seed germination under stress limits yields. Shockwave treatments enhance seed permeability via mechanotransduction. This study evaluates moderate shock pulses (6 pulses) for optimal germination and physiological enhancement. Seeds received 0 (control), 2, 4, 6, 8, or 10 mechanical shock pulses (Mach 1.7-2.2, ~0.5-2 MPa estimated peak pressure, microsecond rise time) from a diaphragm-based shock tube in air medium. Germination (n=30/replicate, 3 replicates), growth, vigor index, and antioxidant enzymes (SOD, CAT, APX, GST) were assessed after 14 days. ANOVA and LSD (p<0.05) analyzed data. All treatments achieved 100% germination (no significant difference). At 6 pulses, seedling vigor index rose 31% (3107 ± 285 vs. 2364 ± 293 control), plumule length 45% (20.5 ± 6.6 cm), radicle wet weight 61% (2.84 g/seed), with p<0.05 vs. control. Antioxidant enzymes peaked at higher pulses (e.g., SOD 70 ± 1 U/g FW at 10 pulses, 291% control increase). Nutritional analysis showed 12% higher energy (366 kcal) and 11% carbohydrates (78 g) at 10 pulses. Moderate shock pulses (6) optimize growth via mechanosensitive permeability without excess stress.