Given below are two statements. Statement I - There is no need of...

Statement I is correct because callus culture is typically grown on a solid agar medium where agitation is not required. In contrast, suspension culture involves growing cells in a liquid medium, which requires continuous agitation (usually on a rotary shaker) to ensure proper aeration, nutrient mixing, and to prevent the aggregation of cells.

Statement II is incorrect because the standard temperature maintained in a plant tissue culture laboratory is generally around $24^{{}^{\circ}}\text{C}$ to $28^{{}^{\circ}}\text{C}$ (often specified as $25 \pm 2^{{}^{\circ}}\text{C}$), not $18$ to $20^{{}^{\circ}}\text{C}$.

Therefore, Statement I is correct but Statement II is incorrect.

Answer: Statement I is correct but statement II is incorrect.