Morpho-Physiological Attributes of Different Maize (Zea mays L.) Genotypes Under Varying Salt Stress Conditions

Salinity stress is one of the major abiotic factors that arrest physiological characteristics and plant growth. Maize (Zea mays L.) is a moderately salt-sensitive crop and shows genotypic variation for salt tolerance. This study was carried out to screen salt-tolerant genotypes and investigate the growth and physiological responses of maize exposed to salt stress during early growth. Fifteen maize genotypes were tested and subjected to different sodium chloride (NaCl) concentrations (i.e., 0, 50, and 100 mM NaCl) for 30 days in hydroponics using a complete randomized design (CRD) with four replications. NaCl was added in 12.5 mM (for 50 mM treatment) and 25 mM (for 100 mM treatment) increments every other day up to the desired concentration. The analyzed data parameters were the growth attribute (germination characteristics, fresh and dried root and shoot weights) and photosynthetic pigments (chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll, and carotenoids). Multivariate techniques were applied to identify the most important traits in evaluating salinity tolerance. Also, the genotypes were ranked for salt tolerance to identify superior genotypes. The results showed considerable variation for each studied trait across the 15 genotypes under NaCl treatments. Compared with the non-saline control, salt stress significantly decreased biomass production; maximum reduction in shoot fresh weight was recorded for genotype NARC PR-2 (92%), while the least reduction was recorded in NCEV 1530-13 (59%). DrKaPohi genotype had the highest reduction in root fresh weight (89%) and the lowest decrease was observed in NCEV 1530-10 (7%). Moreover, photosynthesis pigments decreased the maximum in SS 2002 by 82% and 97% for chlorophyll and carotenoids, respectively. Two clusters were obtained after applying a Cluster Analysis (CA), and Principal Component Analysis (PCA) nominated some morphological trails as efficient criteria for screening salt tolerance of maize during early growth. Based on the mean shoot dry weight ratio +/- one standard error, the 15 genotypes were categorized as salt-tolerant (4 genotypes), moderately tolerant (6), and salt-sensitive (5). Among the genotypes, NLEV-2 and 1270-5 were found to be most sensitive genotypes to salt stress. The more salt-tolerant genotypes (such as CEV-2, NCVE-9, and NCEV 1530-12) showed relatively good ability to cope with salinity effect and could be valuable for developing high-yielding maize hybrids in future breeding programs under salt stress conditions.