Some Considerations Regarding Experimental Design

Although it is virtually impossible to do ideal experiments with intact plants, certain considerations should be kept in mind in all experiments. Manipulations of whole plants are at best disruptive. Specifically, cutting a plant or plant part will inevitably produce a wound response and in addition it will interrupt hormonal signals which would have been received in the intact plant. Replacing plant parts with variously applied hormones may lead to the presence of the hormones in unnatural places, and to unusual metabolism of these hormones both at the cut surface and within the plant. In addition exogeneously applied hormones may increase an endogenous pool to the point of producing hormone imbalance and metabolic disturbance. 

An increasingly important consideration is the unequivocal identification and quantification of hormones extracted from the plant. Clearly, to determine when a hormone is performing as a hormone requires that distinctions between active, accessible, and inactive, less accessible, or stored forms of the hormones should be made where possible. Long-term experiments require careful analysis of the processes and kinetics involved, and the careful consideration of the possibility of any intermediate steps. In addition, the presence of microorganisms, as contaminants, is likely to affect both long-term and short-term processes, and, therefore, should be avoided, if possible (Libbert and Risch 1969). 

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