There is an increase in . . . . . . . . under drought conditions

There is an increase in ABA content, Ethylene content, and also proline content under drought conditions.
Under drought stress, ABA levels were found to be significantly enhanced in the developing seed.
Under drought, the production of ethylene increases and results in an initial increase, drought induces the de novo synthesis of ACS, the rate-controlling enzyme of the ethylene biosynthesis pathway.
Proline accumulates in the leaf under drought stress. Compared to roots and stems, the proline content of the leaf was higher by 1 h post-drought stress and reached the peak.