Maize growth and physiological dynamics: Arsenic uptake modulation under combined abiotic stresses of salinity, boron and arsenic

Abstract

Soil salinity and relatively high boron (B), frequently co-occur in agricultural environments, posing significant challenges to crop growth and productivity. This inhibitory effect on plant growth can be further exacerbated when crops like maize (Zea mays L.) are exposed to the arsenic (As) contaminated soils and irrigation water, along with elevated salinity and B levels. Understanding these combined effects is crucial for optimizing crop resilience. A hydroponic study was conducted to assess the interactive effects of high B and As under saline conditions on maize. Plants were stressed with salinity (60 mM NaCl), boron (3 mM H₃BO₃) and arsenic (40 µM Na₃AsO₄) alone and in combination. A 20-day stress period caused significant reduction in overall growth, with more pronounced effect under combined stress. Root and shoot dry biomass was decreased by 63.45 and 57.84% while leaf area and chlorophyll index (SPAD value) were diminished by 56.34 and 64.23%, membrane stability index (MSI) and leaf relative water contents (RWC %) were reduced by 63.92 and 61.59% upon exposure to these combined stressors as compared to the control treatment. Arsenic stress increased the shoot and root As accumulation by 52.4 and 84.6-fold, respectively. However, high B and salinity effectively suppressed these levels due to their negative correlation with As uptake. Further in-depth phytometric profiling is needed to understand the underlying mechanisms of plant stress tolerance and nutrient homeostasis under these combined stresses.