Describe the method of Ganongs potometer to measure the rate of tranpiration.

Explanation

Ganongs potometer is used to measure the rate of transipration indirectly.In this the amount of water absorbed is measured and assumed that this amount is eaqual to the amouunt of water tranpired.
Apparatus consists of a horizontal graduated tube which is bent is opposite directions at the ends.On bent end is wide and the other is narrow.A reservoir is fixed to the horizontal tube near the wide and the other is narrow. A reservoir is fixed to the horizontal tube near the wider end.The reservoir has a stopcock to regulate waterf flow .The appartus is filled with water from reservoir .A twig or a small plant is fixed to the wider arm through a spilt cock.The other bent end of the horizontal tube is dipped inti a breaker containing coloured water.An air at the narrow end .Keep this graduated tube at the narrow end .Keep this apparatus in bright sunlight and observe.As transpiration takes place,the loss is compensated by water absorption through the xylem portion of the twig,the rate of water absorption is equal to the rate of transpiration.