The calcium present in the milk acts as a fertilizer, for the growth of pumpkin size.
Explanation:
Scientific answer: Milk contains nutrients, minerals mainly calcium which are good for the growth of the plant as a fertilizer.
Milk gets readily absorbed by the roots due to the solubility of nutrients in milk.
The root hairs of the plant transport the calcium to the other parts like stem.
This will only help when all other factors of plant growth are present as sunlight, water other than fertilizer.
Non-scientific question:
The Hypothesis here is those pumpkin plant fed with milk are bigger on size.
Also injecting stems with milk would cause no good.
Pumpkin plants fed with milk and some plants fed with water are compared, we get the result that giant pumpkins are one that are fed with milk. This is statistical analysis.
