Plant perception (physiology) auxin redistribution occurs in a way to produce differential growth away from gravity. For perception to happen, the plant must sense, perceive and translate the direction of gravity. Without gravity, proper orientation will not occur and the plant will not effectively grow. The root will not be able to uptake nutrients or water, and the shoot will not grow towards the sky to maximize photosynthesis. Plants do not have a brain or neuronal network, but reactions within signalling pathways may provide a biochemical basis for learning and memory in addition to computation and problem solving. Controversially, the brain is used
Plant nutrition Plant nutrition Plant nutrition is the study of the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply. In 1972, Emanuel Epstein defined two criteria for an element to be essential for plant growth: This is in accordance with Justus von Liebig's law of the minimum. The essential plant nutrients include carbon, oxygen and hydrogen which are absorbed from the air, whereas other nutrients including nitrogen are typically obtained from the soil (exceptions include some parasitic or carnivorous plants). There are seventeen most important nutrients for plants. Plants must obtain the following mineral nutrients from