the pot size (volume) is the most accurate factor affecting the growth of plants when grown in pots. In this case, the volume in cm3, liters or gallons are the correct units (depending on if you are using SI system or not). When publishing in international journals, you must use liter as a measuring unit. the authors who are using cm2, probably they are investigating the soil surface area rather than the volume of the root zone. So, if you are going for example to study the water use of the plant, you should consider the surface area of the pots to account for evaporation.

I agree with Dr. AMR. I am doing my work in Pots now and volume is the most accurate way to representing the Pots size. But still you can test the effect of Pot width and depth on plants specially roots this may give you a good results. Good luck

In my opinion, in 5 treaments: (1.5cm, 2cm, 2.5cm, 3cm, 3.5cm), do this experiment to the size you said, and check the effect of the size and size of the pot until the best size To be determined.

When you report and publish your study you need to report it in away that another researcher can repeat it, therefor give the most information that needed. Now if you study the effect of pot size, then you should report the diameter and volume of the pot too. In many countries some pot sizes are standard and when we use them, we report in a general way as 4cm, 1liter, 1gal or 5 gal.

The liters are common unit used in international journals.

I Agree With Esteban Blanco Camejo

I agree with Chaim Kempler.

To ensure you are measuring through the middle of the pot, hold the ruler down on one side of the pot and then move it back and forth on the other side until you find the widest point. For square and rectangular planters, measure the length and width of the inside opening. Finally, measure the depth of the planter.