Biochar as a Potential Strategy for Enhancing Wheat Production in Arid Soils under deficit irrigation practices

Deficit irrigations, combined with biochar, could be an effective solution to aleviate drought stress in wheat; thereby enhancing its productivity in arid soils. To test this hypothesis, a greenhouse experiment of a randomized complete block design was conducted, comprising two factors: (1) two levels of deficit irrigations at 60 and 80% of soil field capacity (designated as FC60 and FC80, respectively) and (2) three biochar doses, i.e. 0, 5 and 10 g kg-1 (refered to as B0, B5 and B10, respectively). Plants grown on a soil irrigated at 100% of the field capacity without biochar application served as a reference control treatment. This brought the total number of treatments to seven. Results obtained in this study revealed that root biomass increased significantly with deficit irrigation; yet wheat shoots and grains decreased considerably. On the other hand, the application of biochar, generally enhanced shoot and grain yields while decreasing root growth. This in turn augmented both shoo-to-root and grain-to-shoot ratios. In this regard, the highest increase in grain yield was observed for B5+FC100, while the highest increase in shoot –to-root ratio was recorded for the B10+FC100 treatment. Biochar upgraded the coping strategies of wheat plants under drought stress by increasing the osmoregulator proline in shoots, Mn content in roots and Cu concentrations in different plant parts, especially at the highest application rate (B10). These two nutrients (Mn and Cu) are incorporated into detoxifying enzymes that neutralize superoxide radicals which accumulate under abiotic stress. Nevertheless, the high dose of biochar likely immobilized soil nutrients and reduced their concentrations in different plant parts. Overall, residual organic matter increased in biochar-amended soil, and its consequences on soil pH were not significant. This could guarantee sustainable crop production in such soils. In conclusion, the combination of deficit irrigation and biochar application can be used successfully to increase wheat production in arid soils, while optimizing irrigation water use and sustaining soil productivity.