No, I have never heard that topping peas to increase production but I do know this works with producing more blooms on Sweet Peas. Why not experiment? Pinch out the top third of one or two pea seedlings and compare them to your control peas as growth continues. Please let us know if the peas you shortened produced more peas to harvest. Gardening is an adventure and we are always learning. Keep growing, Marianne Binetti