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--- invisible_gardens [2014/11/24 10:11] – [PRE OPENING of the GREEN LIGHT DISTRICT exhibition: wednesday 05/11/2014] ami
+++ invisible_gardens [2016/01/13 17:48] – external edit 127.0.0.1
@@ Line 88: / Line 88: @@
   * Edible Forest garden zone: http://opengreens.okno.be/garden_timeline.php?id=32
+=====CIRCADIAN RYTHM OF PLANTS=====
+A circadian rhythm is a roughly-24-hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria. The term "circadian", coined by Franz Halberg, comes from the Latin circa, "around", and dies, "day", meaning literally "about a day." The formal study of biological temporal rhythms such as daily, weekly, seasonal, and annual rhythms, is called chronobiology.
+The first endogenous circadian oscillation was observed in the 1700s by the French scientist Jean-Jacques d'Ortous de Mairan who noticed that 24-hour patterns in the movement of plant leaves continued even when the plants were isolated from external stimuli.
+Circadian rhythms may be defined by three criteria:
+• The rhythm persists in constant conditions (for example constant dark) with a period of about 24 hours
+• The rhythm period can be reset by exposure to a light or dark pulse
+• The rhythm is temperature compensated, meaning that it proceeds at the same rate within a range of temperatures.
+Disorders of the circadian rhythm system can result from decreased light activation.
+http://www.browardresearch.com/circadian-09.htm
+{{:greenlightdistrict:lightsensor.png?500X123|}}
+//The graph shows a clearly disturbed rythm of the UV-light from november 1 to november 10.//
+A circadian rhythm is any biological process that displays a built-in oscillation of about 24 hours. These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, and fungi. The formal study of biological temporal rhythms is called chronobiology. Although circadian rhythms are self-sustained, they are adjusted to the local environment by external cues, commonly the most important of which is daylight.
+Plant circadian rhythms tell the plant what season it is and when to flower for the best chance of attracting pollinators. Behaviors showing rhythms include leaf movement, growth, germination, stomatal/gas exchange, enzyme activity, photosynthetic activity, and fragrance emission, among others.[32] Circadian rhythms occur as a plant entrains to synchronize with the light cycle of its surrounding environment. These rhythms are endogenously generated and self-sustaining and are relatively constant over a range of ambient temperatures. Important features include two interacting transcription-translation feedback loops: proteins containing PAS domains, which facilitate protein-protein interactions; and several photoreceptors that fine-tune the clock to different light conditions. Anticipation of changes in the environment allows appropriate changes in a plant's physiological state, conferring an adaptive advantage.
+Light is the signal by which plants synchronize their internal clocks to their environment and is sensed by a wide variety of photoreceptors. Red and blue light are absorbed through several phytochromes and cryptochromes.
+http://en.wikipedia.org/wiki/Circadian_rhythm
+The light sensor used to measure the UV light is an analog sensor bought at Adafruit NY.
+https://learn.adafruit.com/adafruit-ga1a12s202-log-scale-analog-light-sensor
+{{:greenlightdistrict:lightsensor-ga1a1s202wp_spec.pdf|This is the datasheet}}.
 =====GARDEN IN 3D=====
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 Volgens Rufin hebben de olijfbomen in het begin te wieinig water gekregen. Door de warmte is er een groter vochtverlies en moeten de planten meer water hebben. Rufin heeft ze nu goed door-en-door bewaterd, en we hopen dat de bladeren terug gaan komen.
 Maar al bij al blijft de Invisible Garden een installatie in progress, met levende materialen kan men ook niets anders verwachten.
+Zonet enkele snapshots van de tuin op 24/11/2014 doorgestuurd gekregen.
+Wat je ziet is normaal, gezien de omstandigheden:
+- dat de planten uit hun biologisch ritme gehaald zijn en zich terug moeten aanpassen (van buiten naar binnen)
+- dat de planten de eerste 10 dagen eenzeer onregelmatig dag/nacht ritme hebben gehad omdat de lichten en/of de timers nog niet werkten => dis probleem is nu gelukkig opgelost maar heeft zeker een invloed op het bladverlies
+- dat er, gezien de warme omstandigheden in de 'atelier2', misschien iets te weinig water is gegeven tot nog toe (omdat het door de warmte sneller verdampte dan gewoonlijk) => Rufin gaat daar nu op letten
+- dat we werken met levende materie die in evolutie is en die naast zijn eigen bioritmew onderhevig is aan externe factoren als licht, temperatuur en vochtigheid
+- dat het sowieso herfst is, en de winter moet nog komen!
+Het enige wat nog nog dringend moet gebeuren: ik moet asap kunnen checken hoeveel micromol licht er exact door de UV lampen wordt afgegeven. Indien dit niet voldoende blijkt, moeten we misschien enkele lampen bijsteken. De armaturen hangen er al, dus moest dit nodig zijn is dit geen groot werk.