2012). The first validated allelochemical was juglone (5,hydroxyl-1,4naphthoquinone), which emanates from black walnut (Juglans nigra) (Williamson
and Weidenhamer 1990). As illustrated in Fig. 5.1, (Grummer 1955) special terminologies are used for the chemicals involved in allelopathy based on the kind of plant
producing the compound and the type of plant affected. They are as follows:
1. Antibiotic – a chemical substance produced by a microorganism that inhibits and
is effective against a microorganism.
2. Phytoncide – an inhibitor compound produced by higher plants that affect the
microorganism.
3. Marasmins – the biochemical compounds produced by microorganisms and
detrimental to the higher plants.
4. Kolines—the biochemical compounds produced by the higher plants and effective against higher plants.
However, with the exemption of antibiotics, these descriptions have received
narrow usage.
Most researchers have selected to use the broad terminology of allelopathic
chemicals or allelochemicals. Allelochemicals can be classified into ten categories
(Li et al. 2010a, b), conferring to their structural relationship in R moiety and
characters:
1. Water-soluble organic acids, straight-chain alcohols, aliphatic aldehydes, and
ketones.
2. Simple lactones.
Fig. 5.1 Special terminologies for allelopathic compounds involvement in the plants
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H. Palanivel et al.
and Weidenhamer 1990). As illustrated in Fig. 5.1, (Grummer 1955) special terminologies are used for the chemicals involved in allelopathy based on the kind of plant
producing the compound and the type of plant affected. They are as follows:
1. Antibiotic – a chemical substance produced by a microorganism that inhibits and
is effective against a microorganism.
2. Phytoncide – an inhibitor compound produced by higher plants that affect the
microorganism.
3. Marasmins – the biochemical compounds produced by microorganisms and
detrimental to the higher plants.
4. Kolines—the biochemical compounds produced by the higher plants and effective against higher plants.
However, with the exemption of antibiotics, these descriptions have received
narrow usage.
Most researchers have selected to use the broad terminology of allelopathic
chemicals or allelochemicals. Allelochemicals can be classified into ten categories
(Li et al. 2010a, b), conferring to their structural relationship in R moiety and
characters:
1. Water-soluble organic acids, straight-chain alcohols, aliphatic aldehydes, and
ketones.
2. Simple lactones.
Fig. 5.1 Special terminologies for allelopathic compounds involvement in the plants
96
H. Palanivel et al.