Foliar Application of Folic Acid on Cabbage Seedlings Grown under Restricted Irrigation Conditions Can Alleviate the Negative Effects

Drought, a critical abiotic stress worsened by climate change, poses a substantial threat to crop production and global food security. White cabbage is classified as a moderately drought-sensitive crop. The function of folic acid, otherwise known as folate, in the plant's response to drought conditions is not yet fully understood. The aim of the study was to evaluate the potential of folic acid in enhancing certain growth parameters and physiological traits of cabbage seedlings under limited irrigation conditions. In this investigation, the effects of FA as a foliar application at 0, 100, and 200 µM (FA0, FA1, and FA2, respectively) were examined on white cabbage seedlings grown under full-irrigation (I0) and restricted irrigation (I1), set to 50% of full capacity irrigation scheme (I0). Drought stress adversely affected the plant growth properties of cabbage seedlings, whereas FA treatments mitigated the adverse effects of drought stress on the plant growth properties of cabbage seedlings. Under restricted irrigation, plants treated with 100 µM FA (FA1) had higher plant height, stem diameter and leaf area, while plants treated with 200 µM FA (FA2) had higher plant dry weight and plant dry matter content. Plant fresh weight increased with FA treatments under restricted irrigation, but no significant difference was observed between doses. On the other hand, leaf relative water content (LRWC), which decreased under restricted irrigation conditions, increased with FA applications regardless of the dose, while electrical conductivity (EC), which increased under the same conditions, decreased with 100 µM FA (FA1) application. Leaf number, root fresh weight, root fresh weight, root dry weight, root dry matter content and chlorophyll value (SPAD) were not affected by FA treatments under both restricted and full irrigation conditions. In conclusion, foliar spray of folic acid in cabbage can be recommended as a potential application to alleviate drought stress.