If you touch the leaves of Mimosa pudica, it folds and wilts. What kind of movement is this?
This is seismonastic movement. Here, the plant respond to diffused stimulus i.e. our touch or shock .
Write the physiological effects of gibberellins in plant growth.
Physiological effects of gibberellins are:-
Many plants respond to application of GA by a marked increase in stem length; the effect is primarily one of internode elongation.
Besides general increase in stem length, gibberellins specifically induce internodal growth in some genetically dwarf varieties of plants like Pea and Maize. It appears that dwarf- ness of such varieties is due to internal deficiency of gibberellins.
Gibberellins induce sub-apical meristem to develop faster. This causes elongation of reduced stem or bolting in case of rosette plants (e.g., Henbane, Cabbage) and root crops (e.g., Radish).
Gibberellins overcome the natural dormancy of buds, tubers, seeds etc., and allow them to grow. In this function they are antagonistic to abscisic acid (ABA).
During seed germination, especially of cereals, gibberellins stimulate the production of some messenger RNAs and then hydrolytic enzymes like amylases, lipases and pro
teases. The enzymes solubilise the reserve food of the seed. The same is transferred to embryo axis for its growth.