Abstract

                                It is a well known fact that organic constituents of soil can improve plant growth. But are there organic compounds in soils called ("Toxins") which are detrimental to plant growth? This question has occupied the minds of workers interested in crop production for a number of years. There was considerable controversy among research workers during the early ninteen- hundreds about the existence of toxins; it is now fairly well accepted that there are substances in soil which, under certain conditions, can be harmful to plant growth. These organic compounds or phytotoxic compounds in soils and plants have been isolated and studied using new techniques such as paper, gas and column chromatography and infra-red spectrophotometry. The purpose of this paper is to review research on microbiological decomposition products and organic substances in plant and soil residues which are known to be inhibitive to plant growth. An attempt has been made in this paper to review all the literature available so far on this subject.

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