Lodging of cabbage seedling due to its own weight

The machinery used to harvest cabbages has a preprocessing unit that holds the stem and cuts it off under the cabbage head. Mechanical harvesting damages the cabbage head because the stem often bends. However, why the bending occurs is not known. The stem sometimes bends due to the cabbageʹs weight and environmental factors. This study aimed to clarify the mechanical characteristics of the cabbage hypocotyl and understand pliability of the cabbage stem. We investigated pliability of the cabbage stem, particularly the hypocotyl segment under the cotyledonary node, during the seedling stage. Flexural rigidity of the cabbage hypocotyl, a mechanical characteristic of pliability, was measured. It was found that flexural rigidity increased exponentially in proportion to the number of days elapsed. A simple model of the cabbage stem was constructed to examine whether the hypocotyl can bend due to weight and the deflection of the hypocotyl was simulated based on the data obtained. The hypocotyl showed maximum bending on the 21st day from the day of sowing.