Guttation is cause due to A. High water potential B. High root pressure C. Low transpiration D. All the above
Hint: The word guttations means loss of water in the form of liquid through tiny openings present on the plant parts. This usually occurs in plants growing in humid and warm climates when there is more water absorption than the transpiration rate. This is a biological process which helps the plants to maintain their balance of water and nutrients. All the plants may not show guttation.
Complete answer: The basics of guttation have been discussed and let us go into the details. We know that plants undergo transpiration where the water is lost in vapour form whereas in guttation, the water is lost in the liquid form through hydathodes. Hydathodes are small openings present on the leaf margins and have xylem vessels in it. Their main function is to secret ions and water so that the sap keeps flowing throughout the plant. At night, there is no transpiration so the excess water present is moved to leaves by the pressure created in roots as a result is the guttation. The water content in soil is more than roots, so as a result of water potential, water moves from soil to roots which further increases the root pressure. All these factors i.e. low transpiration,high water potential and root pressure contribute to the guttation process.
So, the correct answer is option D
Note: One should never get confused with guttation and dew. In guttation, the water exudated comes from the soil whereas dew is formed as a result of condensation of atmospheric moisture. Guttation can occur in plants like wheat, barley and cannot be seen in large trees. As guttation is related to root pressure, enough pressure would not be generated to force the water upwards in large trees.