Abstract:
Investigating root water uptake (RWU) is necessary since it has direct relationship with water use efficiency and crop productivity. However, abiotic stresses negatively influence theRWU rateespecially under salinity stress conditions.In this works, a field and a column experiment werecarried out to test the hypothesis thatbiochar soil amendments (BA) could increase the okra RWU, water balance, improve water productivity and alleviate salt stress.For column experiment, twoBA applications (BC0, 0% and BC1, 10% w/w) were considered for three irrigation water salinity levels, i.e.0.75 dS m-1 (S0), 3.0 dS m-1 (S1) and 6.0 dS m-1 (S2).. For field experiment, three BA soil applications, i.e. 0 ton ha-1 (B0), 12.5 ton ha-1 (B1) and 25 ton ha-1 (B2), were considered for the sameirrigation water salinity levels. The HYDRUS-1D model was utilized to simulate and evaluate the effects of BA on okra RWU for each salinity treatment under field conditions. The model was calibrated and validated using the column experiment.The results obtained showed that, for non BA treatments, the maximum value of RWU (0.45 cmday-1) was obtained in S0 while S2 gave the minimum value (0.30 cmday-1). The B1 increased the RWU by 2%, 5% and 16 % for S0, S1 and S2, respectively. Meanwhile for B2, the increment in RWU under S0, S1 and S2 were 4%, 5% and 26 % respectively. The results indicated that biochar diminished salt stress in Okra by adsorbing transient sodium ions and reducing ion toxicity, while releasing potassium, calcium, and magnesium ions to the soil solution. Hence, BA can be considered as an effective practice to enhance RWU under salt stress and alleviate the negative salinity impacts.
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