Spectral Light Quality Regulates Photosynthesis and Thylakoidal Protein Complexes to Improve Drought Tolerance in Okra Rootstocks

Introduction: Global agriculture is seriously threatened by drought stress, especially in arid and semi-arid areas where crop production is already low. Under water-deficit instances, okra (Abelmoschus esculentus L.), a nutritionally beneficial but underutilised crop, experiences considerable productivity and quality losses. Plant cellular activities are modulated by light quality, which has an impact on stress adaptation. In order to increase okra productivity and stress resilience, this study attempts to optimize the performance of drought-resilient rootstocks under various spectral light conditions.

Methods: Two okra genotypes, NS 7772 and NS 7774, were evaluated in this study under drought conditions with two light spectra: red: blue: white (R: B) light emitting diodes (LEDs) and white light (100%).

Results and discussion: Infrared thermographic images revealed lower canopy temperatures, indicating increased relative water content. Decreased malondialdehyde (MDA) levels, as well as increased antioxidant enzyme activity were indicators of NS-7774's better drought tolerance. Better metabolic stability was indicated by thylakoidal multiprotein complex profiling, which showed that NS 7774 under R: B preserved photosynthetic protein complexes and induced stress-responsive polypeptides. Nutrient preservation under stress validated by SEM-EDAX. Chlorophyll, total soluble protein, isoenzyme patterns and antioxidant activity (CAT, SOD, APX and GPOX) were assessed.  Around 19 variables were subjected to multivariate analysis, among which six components were found to be important factors in contributing to resilience. These results demonstrate that combinational spectral light modifications can greatly increase the tolerance of okra to drought. The superior performance of NS 7774 under red:blue (R:B) light conditions suggest the potential suitability of NS 7774 for cultivation in drought-prone zones of India