Name various plant hormones and describe their physiological effects on plant growth and development.

(N/A) The major plant hormones (phytohormones) and their physiological effects are as follows:
$1$. $Auxins$: These promote cell enlargement and cell differentiation. They are responsible for apical dominance,root initiation in stem cuttings,and preventing fruit and leaf drop at early stages.
$2$. $Gibberellins$: These promote stem elongation,seed germination,and flowering. They are also involved in breaking seed dormancy and increasing the size of fruits like grapes.
$3$. $Cytokinins$: These promote cell division (cytokinesis). They help in delaying senescence (aging) in leaves,promoting lateral bud growth,and overcoming apical dominance.
$4$. $Abscisic \ acid$ $(ABA)$: This is a growth inhibitor. It promotes dormancy in seeds and buds,induces leaf abscission (falling of leaves),and causes closure of stomata during water stress.
$5$. $Ethylene$: This is a gaseous hormone that promotes fruit ripening and senescence of flowers and leaves.