Effects of Cinnamic Acid on the Root Growth of Cucumber (Cucumis Sativus L.) and Figleaf Gourd (Cucurbita Ficifolia Bouché) Seedlings

The study investigated the effects of cinnamic acid (CA) on the root growth and hormone content of cucumber and figleaf gourd seedlings. CA at various concentrations was found to decrease primary root elongation, total root elongation, and root hair growth rates in both plants, with a stronger inhibitory effect on cucumber. CA stress increased the average root diameter and root hair density, with cucumber showing a larger increase in root diameter but a smaller increase in root hair density compared to figleaf gourd. Additionally, CA stress elevated indole acetic acid (IAA) content and ethylene (ET) production rates in both plants, with cucumber experiencing a 16% higher increase in IAA content but a 51% lower increase in ET production rate than figleaf gourd. The findings suggest that figleaf gourd is more resistant to CA stress due to its lower increase in IAA content and higher ET production rate, which contributes to greater root hair density.