Response of Elite Onion Genotypes to Drought Stress: Morphophysiological and Agronomic Parameters and Stress Indexes

Onion productivity is sensitive to dry conditions. Breeding tolerant onion genotypes could improve productivity in regions vulnerable to water deficit stress. In this study, morphophysiological and yield parameters were used to evaluate the effects of drought on 14 genotypes at different growth stages. Three replications and two treatments-control and drought-were used in the split-plot design experiment, which was carried out in a greenhouse. For 10, 25, and 25 days during growth, bulb initiation, and bulb development, respectively, drought was applied. The findings showed that onions' susceptibility to drought depends on the growth stage and stress level. Morphological and physiological parameters decreased dramatically as plant developmental stages varied and the stress duration increased. After 25 days of stress during bulb development, all parameters demonstrated a significant decrease (<i>p</i> < 0.001). Onions' proline content did, however, rise as a result of the drought. The study found that drought during bulb development considerably decreased yield by 33.85% (<i>p</i> < 0.001). Responses to drought stress varied among the various onion genotypes. Goudami, Prema, and Red_Jewel F1 were drought-tolerant, while Red_Creole, AVON_1074, and Safari were sensitive, and Local, AVON_1317, and Dayo displayed intermediate tolerance. The tolerant genotypes may be useful for improving regions vulnerable to drought.