2.2 Release of Allelochemicals
Plants use different methods to release allelochemicals by exudation, through crop
residue decomposition in the soil, through leaching from aerial parts, volatilization,
and pollen spreading in some plants (Hameed et al. 2019). Volatilization and
leaching (Bertin et al. 2003) are the two main processes of the release of
allelochemicals into the atmosphere or rhizosphere. Recently, Pereira et al. (2016)
reported that the volatile mode of release of allelopathic compounds (allelopathins)
would broadly reign in plants thriving in hot, dry climates, whereas water-soluble
allelopathins would preponderate in wetter climates (Pereira et al. 2016). Different
methods for the release of allelochemicals into the atmosphere or rhizosphere under
the suitable physiological, environmental, and ecological conditions are listed hereunder and described in Fig. 5.3.
1. Leaching – The allelochemicals leached through precipitation, due to the moisture content in the air through dewdrops, rain, or flooding, which may ooze out
the allelopathic chemicals from the aboveground plant parts and consequently
deposit them on other plants or into the soil. Leaching may likewise happen
through plant residues (Bertin et al. 2003; Cruz-Ortega et al. 2002).
2. Volatilization – The allelopathic compounds are discharged into the atmospheric
air. It is culpable only if the atmosphere was in dry, hot, or semiarid conditions.
The allelochemicals might be engrossed as vapors by neighboring or surrounding
plants, by the condensation form of these vapors as dew, or the condensate may
reach the rhizosphere and absorbed by the roots (Putnam and Tang 1986).
Fig. 5.3 Release and mode of action of allelochemicals in different environmental and ecological
conditions
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H. Palanivel et al.
Plants use different methods to release allelochemicals by exudation, through crop
residue decomposition in the soil, through leaching from aerial parts, volatilization,
and pollen spreading in some plants (Hameed et al. 2019). Volatilization and
leaching (Bertin et al. 2003) are the two main processes of the release of
allelochemicals into the atmosphere or rhizosphere. Recently, Pereira et al. (2016)
reported that the volatile mode of release of allelopathic compounds (allelopathins)
would broadly reign in plants thriving in hot, dry climates, whereas water-soluble
allelopathins would preponderate in wetter climates (Pereira et al. 2016). Different
methods for the release of allelochemicals into the atmosphere or rhizosphere under
the suitable physiological, environmental, and ecological conditions are listed hereunder and described in Fig. 5.3.
1. Leaching – The allelochemicals leached through precipitation, due to the moisture content in the air through dewdrops, rain, or flooding, which may ooze out
the allelopathic chemicals from the aboveground plant parts and consequently
deposit them on other plants or into the soil. Leaching may likewise happen
through plant residues (Bertin et al. 2003; Cruz-Ortega et al. 2002).
2. Volatilization – The allelopathic compounds are discharged into the atmospheric
air. It is culpable only if the atmosphere was in dry, hot, or semiarid conditions.
The allelochemicals might be engrossed as vapors by neighboring or surrounding
plants, by the condensation form of these vapors as dew, or the condensate may
reach the rhizosphere and absorbed by the roots (Putnam and Tang 1986).
Fig. 5.3 Release and mode of action of allelochemicals in different environmental and ecological
conditions
100
H. Palanivel et al.