Effect of lemon juice application on salt stress during the early seedling stage in maize

In this study, the responses of different maize genotypes to salinity stress with citric acid and lemon juice applications during the early seedling stage were investigated.The research was conducted in the laboratories and climate chamber of the Field Crops Department, Faculty of Agriculture, Eskişehir Osmangazi University. Initially, the responses of 21 maize genotypes to salinity stress were examined through germination and emergence tests. Based on a cluster analysis of reductions in seedling growth and fresh weight values, the most sensitive genotype (P2088) and the most tolerant genotype (DKC6050) were identified. Subsequently, citric acid applications [control (PW, pure water), citric acid (CA, 100 ppm), and lemon juice (LJ, 0 g/L)] were applied to these two genotypes under saline conditions [control (pure water) and 15 dS m⁻¹ saline conditions] during the early seedling period. The experiments followed a factorial design arranged in randomized plots with four replicates. The results showed that plant height and stem thickness decreased with salt applications. However, in saline conditions, plant height increased with CA application in the DKC6050 genotype. The SPAD value improved with LJ application in the P2088 genotype and with CA application in DKC6050 under saline conditions. Leaf relative water content decreased in P2088 with citric acid application under saline conditions but increased in DKC6050. Electrolyte leakage was higher in the P2088 genotype in a saline environment, but citric acid applications reduced this leakage. Under control conditions, the leaf area of P2088 was larger, but it decreased in both genotypes under saline stress. LJ applications mitigated this reduction and increased the leaf area. Fresh weight was higher in the DKC6050 genotype, although the effect of citric acid was negligible. The dry matter ratio increased in the P2088 genotype with citric acid applications. Stomatal density increased under saline conditions, while stomatal length increased in the P2088 genotype with LJ application. The Na⁺/K⁺ ratio decreased with citric acid applications in the P2088 genotype under saline conditions, indicating increased salt tolerance. In conclusion, initial germination and emergence analyses were insufficient to determine salt tolerance in maize genotypes. Although the P2088 genotype was classified as more sensitive, it demonstrated more favorable responses than DKC6050 in terms of certain morpho-physiological traits and Na⁺/K⁺ ratio under saline conditions with citric acid applications. In order to determine salt tolerance precisely, osmalite accumulation, antioxidant enzyme analyses and ion accumulations should also be evaluated.