Effect of Combined Applications of <i>Ocimum</i> and <i>Moringa</i> Extract‐Based Biostimulants on the Gladiolus Morphophysiological and Biochemical Aspects Under Drought Stress

Drought stress (DS) is the most damaging climatic factor that hinders the growth and ornamental quality of floricultural crops. Improving the floricultural crop's ability to withstand DS is of great importance to the ornamental plants industry. Moringa leaf extract (MLE) as a biostimulant has been reported to improve the DS tolerance in various horticultural crops. However, the potential of ocimum leaf extract (OLE) alone or in combination with MLE needs to be explored under DS conditions. Therefore, the present study aimed to explore the protective roles of OLE and MLE for inducing DS tolerance in gladiolus ( Gladiolus grandiflora L.), which is a vital cut flower crop worldwide. In the first experiment, foliar application of different doses of OLE (10%, 15%, 20%, and 25%) and MLE (2%, 3%, 5%, and 7%) was used for optimization. In the second experiment, the optimized dose of biostimulant was applied to gladiolus under both normal and DS conditions. In the second experiment, plants were divided into two groups: the first group received normal irrigation, while the second group was subjected to DS (60% field capacity). Foliar applications of the biostimulant were applied twice at a 7‐day interval, beginning 1 week after the imposition of DS (four‐leaf stage). A marked reduction in the growth and physiological and biochemical attributes of gladiolus plants under DS was recorded in contrast to the normal condition. Under DS conditions, the best results were noticed in the application of OLE 15% which significantly improved shoot fresh weight by 28%, shoot dry weight by 17%, leaf area by 18%, relative water content by 9%, and membrane stability by 09% compared with the control. Moreover, net photosynthesis rate, transpiration rate, stomatal conductance, substomatal conductance, and water use efficiency were increased by 33%, 30%, 30%, 35%, and 28%, respectively, in DS gladiolus plants supplemented with OLE. Similarly, under DS, OLE application improved the activity of catalase by 37%, by 30%, and superoxide dismutase by 36% while decreasing the level of malondialdehyde by 40% and hydrogen peroxide by 20% compared with normal irrigated plants. The combination of OLE 15% + MLE 3% showed a synergistic effect, due to the complementary interaction of bioactive compounds, improved photosynthetic activity, and enhanced the antioxidative potential of the gladiolus plants under both conditions. These results suggest that OLE and MLE have the potential to mitigate DS in gladiolus plants by improving growth, water balance, gas exchange, and enzyme activity.