Editing Plant physiology (section)

==Environmental physiology==
[[Image:Arabidopsis thaliana.jpg|thumb|[[Phototropism]] in ''[[Arabidopsis thaliana]]'' is regulated by blue to UV light.<ref>{{Cite web |url=http://www.plantphys.net/article.php?id=266 |title=plantphys.net |access-date=2007-09-22 |archive-url=https://web.archive.org/web/20060512073313/http://www.plantphys.net/article.php?id=266 |archive-date=2006-05-12 |url-status=dead }}</ref>]]
{{main|Ecophysiology}}

Paradoxically, the subdiscipline of environmental physiology is on the one hand a recent field of study in plant ecology and on the other hand one of the oldest.<ref name="Salisbury & Ross 1992" /> Environmental physiology is the preferred name of the subdiscipline among plant physiologists, but it goes by a number of other names in the applied sciences. It is roughly synonymous with [[ecophysiology]], crop ecology, [[horticulture]] and [[agronomy]]. The particular name applied to the subdiscipline is specific to the viewpoint and goals of research. Whatever name is applied, it deals with the ways in which plants respond to their environment and so overlaps with the field of [[ecology]].

Environmental physiologists examine plant response to physical factors such as [[radiation]] (including [[light]] and [[ultraviolet]] radiation), [[temperature]], [[fire]], and [[wind]]. Of particular importance are [[water]] relations (which can be measured with the [[Pressure bomb]]) and the stress of [[drought]] or [[flood|inundation]], exchange of gases with the [[atmosphere]], as well as the cycling of nutrients such as [[nitrogen]] and [[carbon]].

Environmental physiologists also examine plant response to biological factors.  This includes not only negative interactions, such as [[competition (biology)|competition]], [[herbivory]], [[disease]] and [[parasitism]], but also positive interactions, such as [[Mutualism (biology)|mutualism]] and [[pollination]].

While plants, as living beings, can perceive and communicate physical stimuli and damage, they do not feel [[pain]] as members of the [[Animal|animal kingdom]] do simply because of the lack of any [[pain receptors]], [[nerves]], or a [[brain]],<ref name="EncyBrit"/> and, by extension, lack of [[consciousness]].<ref>{{cite journal| last1 = Draguhn| first1 = Andreas | last2 = Mallatt| first2 = Jon M. | last3 = Robinson| first3 = David G. | author-link = | title = Anesthetics and plants: no pain, no brain, and therefore no consciousness| journal = Protoplasma| volume = 258| issue = 2| pages = 239–248| publisher = Springer | date = 2021| language = | jstor = | issn = | doi = 10.1007/s00709-020-01550-9| pmid = 32880005 | pmc = 7907021 | bibcode = 2021Prpls.258..239D | id = 32880005| mr = | zbl = | jfm = }}</ref> Many plants are known to perceive and respond to mechanical stimuli at a cellular level, and some plants such as the [[venus flytrap]] or [[Mimosa pudica|touch-me-not]], are known for their "obvious sensory abilities".<ref name="EncyBrit"/> Nevertheless, the plant kingdom as a whole do not feel pain notwithstanding their abilities to respond to sunlight, gravity, wind, and any external stimuli such as insect bites, since they lack any nervous system. The primary reason for this is that, unlike the members of the [[Animal|animal kingdom]] whose evolutionary successes and failures are shaped by suffering, the evolution of plants are simply shaped by life and death.<ref name="EncyBrit">{{cite web
| url = https://www.britannica.com/story/do-plants-feel-pain
| title = Do Plants Feel Pain?
| last = Petruzzello
| first = Melissa
| date = 2016
| website = Encyclopedia Britannica
| access-date = 8 January 2023
| quote = Given that plants do not have pain receptors, nerves, or a brain, they do not feel pain as we members of the animal kingdom understand it. Uprooting a carrot or trimming a hedge is not a form of botanical torture, and you can bite into that apple without worry.}}</ref>

===Tropisms and nastic movements===
{{main|Tropism|Nastic movement}}

Plants may respond both to directional and non-directional [[Stimulus (physiology)|stimuli]].  A response to a directional stimulus, such as [[gravity]] or [[light|sun light]], is called a tropism.  A response to a nondirectional stimulus, such as [[temperature]] or [[humidity]], is a nastic movement.

[[Tropism]]s in plants are the result of differential [[cell (biology)|cell]] growth, in which the cells on one side of the plant elongates more than those on the other side, causing the part to bend toward the side with less growth.  Among the common tropisms seen in plants is [[phototropism]], the bending of the plant toward a source of light.  Phototropism allows the plant to maximize light exposure in plants which require additional light for photosynthesis, or to minimize it in plants subjected to intense light and heat. [[Geotropism]] allows the roots of a plant to determine the direction of gravity and grow downwards.  Tropisms generally result from an interaction between the environment and production of one or more plant hormones.

[[Nastic movement]]s results from differential cell growth (e.g. epinasty and hiponasty), or from changes in [[turgor pressure]] within plant tissues (e.g., [[nyctinasty]]), which may occur rapidly.  A familiar example is [[thigmonasty]] (response to touch) in the [[Venus fly trap]], a [[carnivorous plant]].  The traps consist of modified leaf blades which bear sensitive trigger hairs. When the hairs are touched by an insect or other animal, the leaf folds shut.  This mechanism allows the plant to trap and digest small insects for additional nutrients.  Although the trap is rapidly shut by changes in internal cell pressures, the leaf must grow slowly to reset for a second opportunity to trap insects.<ref>{{cite book| author = Adrian Charles Slack|author2=Jane Gate | title = Carnivorous Plants| year = 1980| publisher = Cambridge, Massachusetts : MIT Press| isbn = 978-0-262-19186-9| page = 160 }}</ref>

===Plant disease===
[[Image:Powdery mildew.JPG|thumb|[[Powdery mildew]] on crop leaves]]
{{main|Phytopathology}}

Economically, one of the most important areas of research in environmental physiology is that of [[phytopathology]], the study of [[disease]]s in plants and the manner in which plants resist or cope with infection.  Plant are susceptible to the same kinds of disease organisms as animals, including [[virus]]es, [[bacteria]], and [[fungi]], as well as physical invasion by [[insect]]s and [[roundworm]]s.

Because the biology of plants differs with animals, their symptoms and responses are quite different.  In some cases, a plant can simply shed infected leaves or flowers to prevent the spread of disease, in a process called abscission.  Most animals do not have this option as a means of controlling disease.  Plant diseases organisms themselves also differ from those causing disease in animals because plants cannot usually spread infection through casual physical contact.  Plant [[pathogen]]s tend to spread via [[spore]]s or are carried by animal [[Vector (epidemiology)|vectors]].

One of the most important advances in the control of plant disease was the discovery of [[Bordeaux mixture]] in the nineteenth century.  The mixture is the first known [[fungicide]] and is a combination of [[copper sulfate]] and [[lime (mineral)|lime]].  Application of the mixture served to inhibit the growth of [[downy mildew]] that threatened to seriously damage the [[France|French]] [[wine]] industry.<ref>{{cite book| author = Kingsley Rowland Stern|author2=Shelley Jansky | title = Introductory Plant Biology| year = 1991| publisher = WCB/McGraw-Hill| isbn = 978-0-697-09948-8| page = 309 }}</ref>