Evaluation of NaCl tolerance in local melon genotypes collected from the Turkish Republic of Northern Cyprus and cultivated in Türkiye under in vitro and hydroponic conditions
Abstract
Salinity is a major abiotic stress limiting melon (Cucumis melo L.) production, particularly during germination and early seedling growth. This study evaluated salinity tolerance in 28 melon genotypes, including local accessions from the Turkish Republic of Northern Cyprus (TRNC), Turkish landraces, and commercial F1 cultivars, using complementary in vitro and hydroponic screening systems. In the in vitro experiment, seeds were exposed to 50, 100, and 150 mM NaCl. Germination declined markedly with increasing salinity, decreasing from 67.1% at 50 mM NaCl to 11.5% and 9.1% at 100 and 150 mM NaCl, respectively. Significant genotypic variation was observed (p < 0.001). Kav 16 and Kav 18 maintained the highest average germination rates (57.1% and 57.0%, respectively), while Şira and Kav 08 also exhibited comparatively high germination under saline conditions. In the hydroponic experiment, seedlings were exposed to 150 mM NaCl, resulting in substantial reductions in all measured growth traits. Compared with the control treatment, plant height, stem diameter, shoot fresh weight, shoot dry weight, root dry weight, and leaf number decreased by approximately 37%, 30%, 46%, 40%, 56%, and 29%, respectively. Significant genotype-dependent differences were detected for all traits. Kav 19 exhibited superior overall growth performance under salinity, whereas Kav 18, Kav 20, Kav 10, and Özbek (F1) also maintained comparatively high biomass accumulation and vegetative growth. Salt tolerance index analysis identified Özbek (F1) (87.3%), Kav 01 (83.3%), Kav 08 (79.8%), Kav 10 (78.3%), and Kav 18 (75.4%) as the most tolerant genotypes. Principal component and correlation analyses further confirmed substantial phenotypic variation in salinity responses among genotypes. The combined use of in vitro and hydroponic screening successfully identified promising melon germplasm for breeding programs targeting salinity tolerance in Mediterranean and semi-arid production environments.