Yes, you can use: "The watermelon crop".
"Η καλλιέργεια" means "the growing of the watermelon or other food. It is the agricultural activity of planting, nurturing, and harvesting a plant." It does not define the plant.
So, if you wrote: "the watermelon crop" it would be accepted because it would refer to that activity.
But the closest correct English is :
"cultivation as seen in the sentence above.
"Η καλλιέργεια του καρπουζιού." Translation:The cultivation of the watermelon.
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Thank you very much!
Surely cultivation refers to the process of growing a crop, and harvesting refers to the bringing in of the crop after cultivation when it is ripe. I don't speak Greek but does the εργεια of καλλιέργεια not refer in some way to the working of the land, preparing the ground, planting seeds, hoeing, watering etc all needing work.
"καλλιέργεια" in the right context can be used both for "cultivation" and "crop".
E.g. γενετικά τροποποιημένες καλλιέργειες genetically modified crops.
συντήρηση των καλλιεργειών crop maintenance
Here's my go-to set of dictionaries. https://www.lexilogos.com/english/greek_dictionary.htm
"crop" refers to the "produce"... "the watermelon that is harvested".
Here we are referring to the cultivation...the growing of the watermelon