Acid growth protons (H ions) to be pumped out of the cell into the cell wall. As a result, the cell wall solution becomes more acidic. This activates expansin activity, causing the wall to become more extensible and to undergo wall stress relaxation, which enables the cell to take up water and to expand. Acid growth Acid growth refers to the ability of plant cells and plant cell walls to elongate or expand quickly at low (acidic) pH. This form of growth does not involve an increase in cell number. During acid growth, plant cells enlarge rapidly because the cell walls are
Jethro Tull (agriculturist) the plant." Again, he declares elsewhere, "That which nourishes and augments a plant is the true food of it. Every plant is earth, and the growth and true increase of a plant is the addition of more earth." And in his chapter on the "Pasture of Plants", Tull told his readers with great gravity that "this pasturage is the inner or internal superficies of the earth; or, which is the same thing, it is the superficies of the pores, cavities, or interstices of the divided parts of the earth, which are of two sorts, natural and artificial. The mouths or