Efficiency of Postharvest Treatments with Citric Acid, Nicotinic Acid and Folic Acid on Stem End Rot of Lemon Caused by Lasiodiplodia theobromae During Cold Storage

Capability of citric acid, nicotinic acid and folic acid as postharvest treatments to induce resistance of lemon fruits against Lasiodiplodia theobromae was investigated in vitro and in vivo. Nicotinic acid and citric acid 3 g/L showed that efficacy in decreaseing fungal growth while folic acid at the same concentration showed no effect of mycelial growth in vitro. Stem end rot incidence on the lemon treated with nicotinic acid was significantly lower than the other treatments either naturally infected or artificially inoculated with Lasiodiplodia theobromae. Quality of treated lemon fruits with nicotinic acid and citric acid were maintained better than the control. The least values of weight loss (%) were obtained by nicotinic acid treatment of naturally infected and artificially inoculated lemons in both seasons in 2023 and 2024. Postharvest treatments with nicotinic acid or citric acid of naturally or artificially infected lemon fruits with Lasiodiplodia theobromae significantly delayed fruit deteriration during cold storage in comparison with other treatments and control. All postharvest treatments had a significant effect on delaying changes of fruit color values (L* and h°), and reduced the decreasing of fruit weight, hardness, TSS and acidity contents, especially those treated with nicotinic acid. Therefore, it could be recommended that treated lemon fruits by nicotinic acid is an effective method to improve its quality and storability during cold storage.