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For the scientific journal of the same name see Plant Physiology (journal).

In botany, plant physiology is the study of the function, or physiology, of plants. Fundamental processes such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, environmental stress physiology, seed germination, dormancy and stomata function and transpiration, both part of plant water relations, are studied by plant physiologists.It is closely related to biochemistry and molecular biology.

One of the leading journals in the field is Plant Physiology, started in 1926. All its back issues are available online for free.[1] Many other journals often carry plant physiology articles, including Physiologia Plantarum, Journal of Experimental Botany, American Journal of Botany, Annals of Botany, Journal of Plant Nutrition and Proceedings of the National Academy of Sciences.

Sir Francis Bacon published one of the first plant physiology experiments in 1627 in the book, Sylva Sylvarum. Bacon grew several terrestrial plants, including a rose, in water and concluded that soil was only needed to keep the plant upright. Jan Baptist van Helmont published what is considered the first quantitative experiment in plant physiology in 1648. He grew a willow tree for five years in a pot containing 200 pounds of oven-dry soil. The soil lost just two ounces of dry weight and van Helmont concluded that plants get all their weight from water, not soil. In 1699, John Woodward published experiments on growth of spearmint in different sources of water. He found that plants grew much better in water with soil added than in distilled water. Stephen Hales is considered the Father of Plant Physiology for the many experiments in the 1727 book, ^[1].

Julius von Sachs unified the pieces of plant physiology and put them together as a discipline. His Lehrbuch der Botanik was the bible of its time. Hydroponics is crop production with mineral nutrient solutions instead of soil containing silt and clay. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel or rockwool. A variety of techniques exist.

Plant physiology researchers discovered in the 1800s that plants absorb essential mineral nutrients as inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant's water supply artificially, soil is no longer required for the plant to thrive. Almost any terrestrial plant will grow with hydroponics, but some will do better than others. It is also very easy to do; the activity is often undertaken by very young children with such plants as watercress. Hydroponics is also a standard technique in biology research and teaching and a popular hobby.

• Plant physiology online study aid
• American Society of Plant Biologists
• New Phytologist free Tansley Reviews
• Vegetable Staticks

• Frank B. Salisbury, Cleon W. Ross Plant physiology Wadsworth, 1992. - ISBN 0-534-15162-0 undergraduate textbook in plant physiology
• Lambers, H. Plant physiological ecology Springer-Verlag New York 1998. ISBN 0-387-98326-0
• Larcher, W. (2001) Physiological plant ecology 4th ed. Springer ISBN 3-540-43516-6
• Duane Isely, "Julius von Sachs" in One Hundred and One Botanists Iowa State University Press, Ames, pp 216-219, ISBN 0-8138-2498-2

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