Abstract
Increased drought due to climate change urges the necessity of adaptive management solutions for sandy soils and crops resilience to water deficiency. Here, the effects of biochar (BC) and super-absorbent polymer (SAP) are compared in terms of soil water retention and alleviation of drought stress in faba bean (Vicia faba L.). A sandy soil was collected from south Tunisia, mixed with BC at 2% (BC1) and 4% (BC2), with SAP at 0.1% (SAP1) and 0.2% (SAP2) and then packed in pots. Changes in soil moisture content due to evaporation were monitored on a daily basis. Moreover, physiological and morphological responses of faba bean to drought stress were analyzed. There was no significant difference in soil water evaporation among BC1 (10.54 +/- 0.36 mm), SAP1 (9.97 +/- 0.82 mm) and SAP2 (10.64 +/- 0.86 mm) treatments. Compared to the control, these hydro-retainers reduced the cumulative amount of evaporative loss by 19, 23 and 18%, respectively. Drought stress has had a negative impact on the vegetative and physiological attributes of faba bean plants. Most of these traits were positively influenced by the application of SAP and BC amendments. However, the extent of the effect was contingent upon the specific type of amendment and the applied rate. Hence, the performance of the applied amendments was in the order: SAP2 > SAP1 > BC2 > BC1. Additionally, through flavonoids and phenolic content assessment, it was found that BC and SAP application enhanced the plant's resistance mechanisms under drought conditions, with SAP yielding better results. Despite SAP exhibiting superior performance compared to BC, both amendments demonstrated positive impacts on soil water retention and faba bean tolerance to water stress, thereby supporting their use for building resilience in sandy soils experiencing drought.
