Does καλλιέργεια mean the act of growing / cultivation or the resultant crop
It's the act of cultivation. The resultant is σοδειά or συγκομιδή.
The other thread in this unit (καρπούζι) explains that καλλιέργεια can also mean "that which is / things cultivated" ie crops. The example given was roughly translated genetically modified cultivations ie crops.