structure and working of stomata
what causes stomatal opening and closing
factors that regulate the opening and closing of a stoma
1. bioiogical rhythm - stomata continue to open and close on an approximately 24 hour clock even when switched to continuous light.
2. intensity of light - light causes stomata to open. the minimum light level for opening of stomata in most plants is 1/1000 to 1/30 of full sunlight, just enough to cause some net photosynthesis.
3. concentration of carbon dioxide - low concentration of co2 cause stomata to open. high carbon dioxide content causes stomata to close. if carbon dioxide-free air is blown across in darkness, stomata open.
4. water balance or humidity - wilting plants close their stomata.