Trichoderma inoculation alleviates Ni stress and improves yield stability of wheat (Triticum aestivum L.) through...

Nickel acts as a hormetic micronutrient at low concentration by stimulating certain physiological responses. However, it triggers oxidative stress at higher levels, negatively affecting plant growth and overall productivity. This study evaluated the Ni-stress alleviation potential of five different strains of Trichoderma. Two wheat cultivars (BARS-2009 and Sarsabz) were exposed to Ni stress at 100 mg/kg, both alone and in combination with Trichoderma inoculation, and assessed for physio-biochemical parameters including antioxidants, photosynthetic activity, anatomical responses, agronomic traits and grain quality. Results showed that Ni stress intensified oxidative stress as evidenced by elevated H₂O₂ and MDA levels. Trichoderma inoculated Ni exposed plants alleviated Ni stress through improvement in AsA-GSH mechanism, upregulation of enzymatic (SOD, POD and CAT) and non-enzymatic (proline, phenols and flavonoids) antioxidants as well as adjustments in root anatomical structures. Ni stress reduced the plant height, spike length, grain number, seed viability and overall grain yield, which were markedly restored in plants treated with Trichoderma strains. Grain nutritional quality was also compromised under Ni exposure, including declines in reducing sugar, starch, ascorbic acid, phenol, flavonoids, sodium and potassium content. Trichoderma inoculation enhanced these contents and lowered Ni accumulation in grains by 14-48% compared with uninoculated Ni-stressed plants. This study demonstrates that tested Trichoderma strains enhance wheat tolerance to Ni stress and offer a sustainable approach for remediation of Ni-contaminated agricultural soils.