Dear Jawad Ali when you refer to "...recorded on control plants of drought...", does it mean that these plants are from the absolute control (without drought neither ANE treatment?

yes

Natural systems are created heterogeneous with the justifications of mother nature. Variability exists between and within micro, macro and large(field) scales in natural systems. Soil is a heterogeneous, polyphasic, porous, particulate and disperse natural system that exhibits spatial and temporal variabilities. As a result, classical and geostatistical analyses are used to interpret variations with different levels of uncertainty. Modeling variations based on measured data (database) is more pronounced to test the trends of variations.

Dear Jawad Ali the phenotypic response to different environments isn't symetric. You should to consider phenotypic plasticity and how a genotype reacts (e. g. the reaction norm) under changing conditions, in this case drought stress. Thus, different reaction norms for the different treatments must be expected. For control, since plants growth under suitable (not unsuitable) conditions, a wider reaction norm might be expected. The increasing of experimental units might help you to reduce the effects of variability.

You must increase your replicant in each treatments for reducing errors.