Silicon (Si) is a beneficial element that alleviates the adverse effects of salinity in plants. Despite extensive evidence of Si-mediated stress alleviation in other crops, information for tropical fruit species such as Passiflora edulis remains limited, especially regarding the efficiency of different application methods. This study evaluated two yellow passion fruit cultivars (BRS Sol do Cerrado and BRS Gigante Amarelo) at the seedling stage under five management conditions: irrigation with 1.2 dS m⁻¹ water (control), 4.0 dS m⁻¹ water (salt stress), and salt stress combined with Si applied via soil, foliar spray, or both (soil + foliar), using silicic acid as the Si source. The experiment was conducted in a completely randomized design in a 2 × 5 factorial arrangement with five replicates. High salinity decreased foliar nutrient concentrations, gas exchange, and seedling quality, whereas Si mitigated these effects depending on the application method and cultivar. Combined soil and foliar application increased nutrient contents, biomass, and the Dickson Quality Index, especially in BRS Gigante Amarelo. These findings provide new insights into Si management for P. edulis and offer practical implications for improving nutrient balance, growth, and seedling performance under saline conditions.

Yellow passion fruit production is frequently limited by water scarcity, necessitating biotechnological strategies to ensure seedling quality. This study investigated the synergistic effects of Bacillus aryabhattai (Auras^®) and silicon (Si) as mitigators of water deficit in Passiflora edulis seedlings. The experiment was conducted in a greenhouse in Catolé do Rocha, PB, Brazil, using 4 dm³ plastic bags. A randomized block design was used with a 4 × 3 + 2 factorial scheme, testing four available water contents (AWC: 50, 60, 70, and 80%) combined with three mitigation strategies (Auras, Si, and Auras + Si), plus two additional controls (50% and 100% AWC). Water deficit severely compromised growth and soil biological activity; however, mitigation treatments significantly improved physiological and biochemical responses. When applied separately, B. aryabhattai inoculation enhanced the accumulation of photoprotective pigments (carotenoids) and secondary metabolites (flavonoids and anthocyanins) under severe drought, while individual Si application provided homeostatic stability to plant biomass, maintaining dry matter production at levels comparable to moderate irrigation. The Auras + Si combination was the most effective, promoting the highest membrane stability, pigment maintenance, and vigorous growth even under 50% AWC. Furthermore, this interaction optimized soil microbial biomass and reduced the metabolic quotient by 56.7% compared to the stress control. These findings demonstrate that the combined application of B. aryabhattai and Si effectively mitigates the negative impacts of water scarcity on the initial development of passion fruit seedlings and soil microbial activity.

Silicon (Si) is a beneficial element that alleviates the adverse effects of salinity in plants, but the efficiency of its application methods remains unclear. This study evaluated two yellow passion fruit cultivars (BRS Sol do Cerrado and BRS Gigante Amarelo) at the seedling stage under five management conditions: irrigation with 1.2 dS m-1 water (control), 4.0 dS m-1 water (salt stress), and salt stress combined with silicon applied via soil, foliar spray, or both (soil + foliar), using silicic acid as the Si source. Leaf nutrient contents, morphophysiological traits, and the Dickson Quality Index (DQI) were assessed. Salinity reduced all parameters, whereas silicon mitigated these effects depending on the application method and cultivar. In BRS Gigante Amarelo, the combined application increased leaf C, N, K, Ca, and Mg contents, as well as dry mass, DQI, and gas exchange. In BRS Sol do Cerrado, it also enhanced plant height and biomass while reducing electrolyte leakage. Principal component analysis confirmed that the combined Si application promoted simultaneous recovery of nutrition, gas exchange, and growth. Overall, the combined soil and foliar application proved to be the most effective strategy to enhance growth, nutrient balance, and seedling quality of Passiflora edulis under salt stress.