Enhancing San Marzano dwarf tomato performance: The role of biochar under saline irrigation conditions

A greenhouse experiment was conducted in an unheated greenhouse to study the growth, physiology, metabolic mechanisms and yield of tomato in response to salinity stress with the addition of biochar. It was hypothesized that biochar supplementation could enhance plant growth and yield by mitigating the deleterious effect of salinity from NaCl due to its inherent sorption capacity. Tomato plants were exposed to three concentrations of NaCl (0, 40 and 80 mM) and three different percentages of biochar (0, 1 and 2 % v/v). Biochar supplementation improved the physiological response of salinized plants both at the vegetative stage (increased leaf fresh weight by 41.53 % at moderate salinity levels) and at the end of the experiment due to a significant reduction in the uptake of toxic Na+ (-35 %) and Cl- (-41 %) ions. In addition, biochar application positively influenced the balance of sugars, starch and amino acids, supporting a coordinated metabolic response to salt stress. There were significant increases in metabolites such as proline and γ-Aminobutyric-acid (GABA), contributing to stress adaptation and improved fruit quality. The findings underscore the value of biochar's potential as a sustainable solution for amending soils and improving tomato production under adverse conditions such as NaCl stress.