Question

Spraying of phenylmercuric acetate
A. Increases transpiration
B. Reduces transpiration
C. Increases photosynthesis
D. Causes guttation

Answer 1

Hint: Phenylmercury acetate (PMA) is a compound of organomercury used as a fungicide. In order to protect it, PMA has also been used as an ingredient in eye drops and paint, as a disinfectant, and as a catalyst in polyurethane systems.

Complete Answer:
- Several compounds , especially phenylmercuric acetate (PMA), can induce stomatal closure when sprayed on plant leaves. Most of these PMA experiments were conducted on detached leaves with petioles dipped in water; it was found that transpiration was substantially reduced by stomatal closure, while photosynthesis was reduced to a lesser degree.
- In arid plants, the possibility of reducing plant transpiration by chemical treatment without reducing photosynthesis significantly is of practical importance.
- In addition, a promising tool for the study of soil water-plant interrelations was provided by this method of transpiration regulation. We, in order to satisfy both ends different plants with PMA were sprayed, and stomatal opening, transpiration, and photosynthesis or development were observed.
- The saccharide content was elevated after spraying with the anti-transpirant (PMA). Treated plants displayed a variable response to both drought stress and spraying with different PMA concentrations with regard to the lipid content and content of Ca, Mg and P.
- PMA application improved cuticular resistance to the diffusion of gases. In the case of plant leaves developing in dry soil only, this means that both soil moisture stress and PMA decrease the permeability of non-stomatal epidermal cells.

The correct Answer 8s option (B) Reduced transpiration.

Note: As a fungicide and as a disinfectant, PHENYLMERCURIC acetate (PMA) has been used extensively. The antibacterial activity of mercuric compounds is well known to arise primarily from their interference with essential organism groups of sulfhydryls. However, some microorganisms are known to be immune to mercuric compounds.