Elucidating the growth dynamics of Triticum aestivum through quantitative analysis of chlorophyll fluorescence

A comprehensive understanding of the quantitative relationship among phenotypic and photosynthetic traits at key growth stages in wheat can guide trait selection and management strategies that can contribute to increased productivity. In this study, we quantified the physiological basis of morphological and phenological attributes of wheat using chlorophyll fluorescence analysis. Chlorophyll fluorescence parameters were measured using a handheld MultispeQ V2.0 device, connected to a PhotosynQ platform, for 72 genotypes grown in a randomized complete block design (RCBD). Days to heading (DH), percentage digital ground cover (DGC%), and flag leaf length and width were recorded at specific individual growth stages, and chlorophyll fluorescence parameters were measured at 95, 103, and 108 days after sowing to the grain filling stage. Variance analysis revealed a significant difference among the three measurement time points in the fluorescence parameters. A notable increase in relative chlorophyll content was observed in the flag leaf, which plays a central role in photosynthesis; higher chlorophyll levels enhance light capture capacity and thereby support greater photosynthetic activity. The DGC% played a vital role in radiation absorption and photosynthesis. Significant positive correlations were observed among most fluorescence and physiological traits, although some traits showed negative correlations. Path analysis revealed that leaf temperature and ambient temperature indirectly affected morphophysiological traits via DH. Such relationships may assist breeders in selecting elite genotypes.