A study on the engineering properties of onion crop for designing a digger cum detopper

Understanding the engineering properties of onion bulbs is essential for the effective design of machinery used in harvesting and post-harvest processes. In this study, the agronomic, mechanical and biometric characteristics of the Onion (Allium cepa L.) (Panchganga variety) were evaluated at the harvesting stage. The seedlings were cultivated in sandy loam soil with a spacing of 150 mm between rows and 100 mm between plants. Onion bulbs were located at an average depth of 48.69±6.70 mm below the soil surface, with a coefficient of variation (CV) of 13.75%. The average plant height was 349.47±93.69 mm, corresponding to a CV of 26.81%. The force required to detach the leaves ranged from 54.00 to 89.78 N. The Panchganga bulbs exhibited an oblate shape. The average polar diameter, equatorial diameter and mass of the bulbs were measured as 45.73±6.57 mm, 50.04±7.01 mm and 69.34±18.83 g, respectively. The mean bulk density was found to be 406.69 kg/m³ and the average angle of repose was 24.35°. No significant correlation was observed between the polar and equatorial diameters, nor between bulb mass and either diameter.