HORTICULTURE

Detailed explanation-1: -As the weight of the soil had hardly changed, van Helmont concluded that plant growth cannot only be due to minerals from the soil. He thought that the extra plant material had come from the water alone.

Detailed explanation-2: -What did Jan van Helmont conclude from his experiment? He concluded that most of the mass a plant gained had come from water, because that was the only thing he had added to the pot.

Detailed explanation-3: -Photosynthesis was partially discovered in the 1600’s by Jan Baptista van Helmont, a Belgian chemist, physiologist and physician. Helmont performed a 5-year experiment involving a willow tree which he planted in a pot with soil and placed in a controlled environment.

Detailed explanation-4: -Van Helmont thought that his experiment was evidence that water must be food for plants. He thought that if soil and minerals in the soil were not giving the tree its food, then the tree must be gaining weight by getting food from the water. After all, he had been watering the tree everyday for five years.

Detailed explanation-5: -He planted the tree, watered it and then left it for 5 years. He then re-weighed the tree, which had increased in mass by over 12 stone. He dried the soil and weighed it, showing that the soil was almost the same mass. He concluded that the tree grew by drinking water.