Morpho-Physiological Indices for Identification of Heat Tolerant Wheat Genotypes (<i>Triticum aestivum</i> L.) at Seedling Stage

Morpho-physiological evaluation of a crop’s genetic resources is necessary to find possible genotypes to include in breeding initiatives. The objective of this study was to identify heat-tolerant wheat genotypes among36 mutant lines using morpho-physiological indices. Seedlings of mutant lines and check varieties were grown under both normal (control) and heat-stress conditions in growth chambers. Data were recorded on root-shoot parameters (length, fresh weight, dry weight, and ratio), relative water content (RWC), stability of cell membrane, pigment content, and chlorophyll fluorescence. Two-way analysis of variance showed significant (p < 0.01, p < 0.001) variation among15 morpho-physiological features in both growing conditions. Correlation studies showed that pigment-specific indices (total chl, chl a, chl b, carotenoid, Fv/Fm—chlorophyll fluorescence) had significant positive correlations with root-shoot fresh weight (RFW, SFW) and root-shoot dry weight (RDW, SDW), and negative association with relative water content, stability of cell membrane at both conditions. Hierarchical cluster analysis revealed three primary clusters where cluster III (18 genotypes) showed minimal changes in studied characters than cluster I (11 genotypes) and cluster II (13 genotypes). Results obtained from this study revealed that the identified heat-sensitive (30-2 SSH) and heat-tolerant genotypes (27-2(4), 29-2(2), and 30-2 SSH) of wheat might provide useful breeding materials for enhancing wheat yield even more in this period of uncertain climate change.