Examining Adaptive Responses of Foeniculum vulgare to Elevated Sodium and Chloride Stress in the Root Zone

Severe restrictions on world crop output imposed by soil salinity highlight tremendous challenges that are inadequately addressed by classical salinity remediation approaches. Exploring novel plants with high salinity tolerance and optimal yield is direly needed. We made an effort to evaluate Foeniculum vulgare Mill. for its potential in remediating various salt levels.

The experimental layout was arranged in a completely randomized design with varying salinity levels [control (0mM), 50 mM, 100 mM, 150 mM, and 200 mM NaCl].

Compared to the control, plant height decreased by 41.97% at 200 mM NaCl, accompanied by substantial decrease in fresh weight of shoot (60.71%) and dry weight (54.45%). These biomass reductions were positively correlated with decreased chlorophyll and photosynthetic attributes. The most significant decline, 71.05% was observed in the sub-stomatal CO₂ concentration (Ci). At the highest salinity level, a progressive increase in phenolics (64.71%), ascorbic acids (222%), superoxide dismutase (87.11%), and peroxidase (71.25%) were observed. However, catalase (CAT) activity did not differ with 100, 150, and 200 mM salt levels. Saline conditions also led to an increase epidermal, cortical, and metaxylem cell area, stem and root epidermal thickness. The vascular bundle cell area of root also exhibited maximum increase (186%) in response to salinity.

Our findings offer significant advancements on physio-biochemical, and anatomical mechanisms controlling Foeniculum vulgare adaptation and tolerance to salinity. F. vulgare shows potential as an alternative crop on saline soils, offering mechanisms for understanding plant responses to salinity and breeding salt-tolerance agricultural plants.