Assessing genotypic diversity in Gladiolus grandiflorus L. for tolerance to saline conditions

Abstract

Salinity is a major abiotic stress affecting crop productivity, particularly in commercial cut flower like gladiolus, which is highly sensitive. In this study an attempt was made to note the morphological, physiological and biochemical responses of ten gladiolus genotypes under different salinity levels (0, 45 and 90 mM NaCl) in a semi-arid region of New Delhi, India, during two growing seasons (2022–2024). Growth parameters, including plant height (22.1%), leaf area (37.8%) and number of corms (22.17%) were significantly reduced due to highest salinity stress level (90 mM NaCl) and it varied with the genotypes. Genotypes Little Fawn and Yellow Stone exhibited superior performance, maintaining higher relative water content (86.22 & 83.75%, respectively) at 90 mM NaCl, while chlorophyll levels (declined upto 10.5% at 45 mM, and 23.4% at 90 mM NaCl) compared to more salinity sensitive genotypes like Pusa Srijana (68.1% reduction in RWC and 55.8% reduction in total chlorophyll). The salinity-induced oxidative stress, indicated by increased electrolyte leakage rate (83.3% in Little Fawn and 443.7% in Pusa Srijana) and malondialdehyde content (108.1%), was notably lower in the tolerant genotypes. Principal component analysis (PCA) revealed a strong correlation between growth traits and stress bio-markers, highlighting the resilience of Little Fawn and Yellow Stone. These results demonstrate the potential of selecting and evolving salt-tolerant gladiolus genotypes, offering a pathway for sustainable cultivation in salt-affected areas, thereby supporting the flower industry.