Abstract
Responses of plants to environmental signals have been studied for a long time. These responses are exhibited in the form of morphological and physiological adaptations, and relaying the signal to environment (including other plants) through volatile organic compounds and extrinsic chemicals as well as proteins. However these signals do not correspond to the consciousness in the plants. Recent research in this field has produced evidence of non-physical signals e.g. sound and (electro) magnetic field. Plants produce such signals as well as perceive and respond to these signals. There are many novel techniques that have been used in last three-four decades to understand such signals, mostly acoustic signals. This review summarizes the old knowledge as well as recent developments in the area of generation, perception, integration and processing of acoustic signals by the plants as a response to the environment as well as to communicate among themselves. If understood fully, technological interventions and manipulations of these signals can add an extra tool for crop improvement.