Allelopathy in Agroecosystems: an overview

Abstract

Allelopathy plays an important role in the agroecosys-tems leading to a wide array of interactions between crop-crop, crop-weed and tree-crops. Generally, these interactions are harmful to the receiver plants but provide a selective benefit to the donor. Soil microbes play a key role in determining such interactions as they not only alter the nature of allelopathic interactions but also modify the expression of allelochemicals. Soil sickness problem in the croplands could also be attributed to the allelopathic property or even the autotoxicity. The allelochemicals released largely by the plant residues that are left in the fields after the harvest of crops add to the multifarious problems. If properly managed, these residues could be used for controlling weeds and pests. As is true for any chemical based response, allelopathic interactions are also concentration specific. The promotory functions that are inbuilt need to be worked out and exploited. Now a days allelopathic interactions, in general, and the allelochemicals, in particular, are viewed as an important tool for sustainable weed and pest management, and disease control. In this direction, a number of strategies like use of cover or smother or companion crops for weed management, direct use of allelochemicals as natural pesticides, and even the transfer of allelopathic traits/principles to modern day cultivars are being adopted. The purified allelochemicals and/or their derivatives and even the compounds synthesized on their chemistry can be used as novel agrochemicals for sustainable management in an eco-friendly manner. The present paper aims to discuss all the above mentioned roles and aspects of allelopathy in the agroecosystems.