Q.If a plant is provided with all mineral nutrients but Mn concentration is increased, what will be the deficiency ?

Increasing Mn concentration beyond the optimum causes Mn toxicity, which blocks the uptake of Fe, Mg, and Ca, so the plant shows deficiency symptoms of these elements.

Manganese is an essential micronutrient, needed in small amounts for photosynthetic water-splitting (the oxygen-evolving complex) and enzyme activation. However, mineral nutrients must be supplied within a narrow optimum range - too little causes deficiency, but too much causes toxicity. When Mn concentration in the growth medium is raised well above the normal requirement, it competitively interferes with the absorption and translocation of other cations, specifically preventing the uptake of iron (Fe), magnesium (Mg), and calcium (Ca) at the root and within the plant. As a result, even though Fe, Mg, and Ca are present in the medium, the plant develops their defici …