Drought stress restricts the growth of okra (Abelmoschus esculentus L.) by disrupting its biochemical and physiological functions. The current study was conducted to evaluate the role of selenium (0, 1, 2, and 3 mg Se L⁻¹ as a foliar application) in improving okra tolerance to drought (control (100% field capacity-FC), mild stress (70% FC), and severe stress (35% FC)) imposed 30 days after sowing (DAS). Drought (severe) markedly decreased chlorophyll (32.21%) and carotenoid (39.6%) contents but increased anthocyanin (40%), proline (46.8%), peroxidase (POD by 12.5%), ascorbate peroxidase (APX by 11.9%), and catalase (CAT by 14%) activities. Overall, Se application significantly alleviated drought stress-related biochemical disturbances in okra. Mainly, 3 mg Se L⁻¹ significantly increased chlorophyll (21%) as well as anthocyanin (15.14%), proline (18.16%), and antioxidant activities both under drought and control conditions. Selenium played a beneficial role in reducing damage caused by oxidative stress, enhancing chlorophyll and antioxidants contents, and improved plant tolerance to drought stress. Therefore, crops including okra especially, must be supplemented with 3 mg L⁻¹ foliar Se for obtaining optimum yield in arid and semiarid drought-affected areas.

Anthracnose, caused by Colletotrichum gloeosporioides, is one of the most damaging pepper (Capsicum annum L.) disease. Melatonin induces transcription of defense-related genes that enhance resistance to pathogens and mediate physiological activities in plants. To study whether the melatonin-mediated pathogen resistance is associated with chitinase gene (CaChiIII2), pepper plants and Arabidopsis seeds were treated with melatonin, then CaChiIII2 activation, hydrogen peroxide (H₂O₂) levels, and antioxidant enzymes activity during plant–pathogen interactions were investigated. Melatonin pretreatment uncoupled the knockdown of CaChiIII2 and transiently activated its expression level in both control and CaChiIII2-silenced pepper plants and enhanced plant resistance. Suppression of CaChiIII2 in pepper plants showed a significant decreased in the induction of defense-related genes and resistance to pathogens compared with control plants. Moreover, melatonin efficiently enabled plants to maintain intracellular H₂O₂ concentrations at steady-state levels and enhanced the activities of antioxidant enzymes, which possibly improved disease resistance. The activation of the chitinase gene CaChiIII2 in transgenic Arabidopsis lines was elevated under C. gloeosporioides infection and exhibited resistance through decreasing H₂O₂ biosynthesis and maintaining H₂O₂ at a steady-state level. Whereas melatonin primed CaChiIII2-overexpressed (OE) and wild-type (WT) Arabidopsis seedlings displayed a remarkable increase in root-length compared to the unprimed WT plants. Using an array of CaChiIII2 knockdown and OE, we found that melatonin efficiently induced CaChiIII2 and other pathogenesis-related genes expressions, responsible for the innate immunity response of pepper against anthracnose disease.

Drought stress restricts the growth of okra (Abelmoschus esculentus L.) primarily by disrupting its physiological and biochemical functions. This study evaluated the role of Ascophyllum nodosum extract (ANE) in improving the drought tolerance of okra. Drought stress (3 days (control), 6 days (mild stress), and 9 days (severe stress)) and 4 doses of ANE (0, 0.1%, 0.2%, and 0.3%) were imposed after 30 days of cultivation. The results indicate that drought stress decreases the chlorophyll content (total chlorophyll, chlorophyll a, chlorophyll b, and carotenoid) but increases the activity of anthocyanin, proline, and antioxidant enzymes such as ascorbate peroxidase (APX), peroxidase (POD), and catalase (CAT). Physiological and biochemical plant disturbances and visible growth reduction in okra under drought stress were significantly decreased by the application of ANE foliar spray. ANE spray (0.3%) significantly increased the chlorophyll abundance and activity of anthocyanin, proline, and antioxidants (APX, POD, and CAT). ANE regulated and improved biochemical and physiological functions in okra under both drought and control conditions. The results of the current study show that ANE foliar spray may improve the growth performance of okra and result in the development of drought tolerance in okra.

The synergistic interplay between plant growth-promoting bacteria (PGPB) and elite cauliflower cultivars presents a sustainable approach to enhance crop productivity and nutritional quality. This study evaluated the interactive effects of three Bacillus strains ( B. subtilis, B. thuringiensis, and B. pumilus ) on vegetative growth, reproductive yield, and bioactive compound accumulation in three cauliflower cultivars (‘Lucky’, ‘White Beauty’, and ‘Snow Drift’). Significant genetic variability was observed among cultivars, with ‘Lucky’ consistently outperforming others across all parameters, exhibiting maximum plant height, leaf area, chlorophyll content, curd dimensions, and yield attributes. Among PGPB strains, B. subtilis proved to be the most effective, significantly enhancing vegetative development, reproductive performance, and bioactive compound accumulation, followed by B. thuringiensis . To our knowledge, this study provides the first empirical evidence that cultivar-specific compatibility with B. subtilis amplifies flavonoid accumulation by 46% and curd dry weight by 33.3% in cauliflower, suggesting that this synergistic pair represents a promising strategy for sustainable vegetable production. Novel cultivar-specific synergistic interactions were uncovered: the combination of ‘Lucky’ with B. subtilis produced the highest total yield and maximum anthocyanin accumulation, while ‘White Beauty’ paired with B. subtilis yielded the highest phenolic content, and ‘Lucky’ with B. thuringiensis generated maximum leaf area. Additionally, ‘White Beauty’ treated with B. subtilis exhibited superior chlorophyll content, indicating enhanced photosynthetic capacity. The significant cultivar × PGPB interactions for total yield, phenolics, and anthocyanins underscore the critical importance of strain-specific compatibility for maximizing both productivity and nutraceutical value. These findings provide compelling evidence that strategic integration of genetically superior cultivars with compatible PGPB strains—particularly the ‘Lucky’ × B. subtilis combination—offers a offers a viable and effective for sustainable cauliflower production, has practical implications for developing cultivar-specific bio-inoculant strategies that simultaneously enhance food security and nutritional quality in changing climates.