Effects of biochar and GA₃ on maize growth under defined drought and salinity stress in a pot-based factorial...

Zea mays L. (maize) is a globally important cereal crop whose productivity is highly vulnerable to abiotic stresses, particularly drought and salinity. Biochar (BC) and plant growth regulators such as gibberellic acid (GA₃) have been proposed as sustainable strategies to enhance crop performance under adverse conditions; however, evidence for their combined effects under controlled stress environments remains limited. This pot experiment (10 kg soil per pot) was conducted under a Completely Randomized Design to evaluate BC and GA₃, alone and in combination, under drought stress (40% field capacity) and two levels of salinity stress: 6 dS m^-1 representing high salinity and 2.41 dS m^-1 representing moderate salinity commonly observed in regional irrigated soils. Germination percentage (recorded at 7 DAS), seedling growth (15 DAS), biomass, and chlorophyll pigments (mg g^-1 FW at 21 DAS) were assessed. Under drought, germination decreased to 60% in untreated plants but improved to 79% with BC + GA₃, while shoot length increased from 4.15 to 5.93 cm and root length from 3.65 to 5.43 cm. Shoot fresh and dry weights increased from 1.50 to 2.13 g and 0.70 to 0.90 g, respectively. Under moderate salinity (2.41 dS m^-1), germination improved to 82%, shoot length increased from 20.33 to 22.83 cm, and shoot dry weight from 0.674 to 0.989 g with combined application, while chlorophyll contents were maintained approximately 20-35% higher than stressed controls. Overall, BC and GA₃, particularly when applied together, supported better germination, biomass accumulation, and chlorophyll retention under drought and salinity stress, indicating promising potential under pot conditions, although field validation remains necessary before agronomic recommendations can be finalized.