What Is Allelopathy?
Allelopathy refers to the beneficial or harmful effects of one plant on another plant, both crop and weed species, from the release of biochemicals, known as allelochemicals, from plant parts by leaching, root exudation, volatilization, residue decomposition, and other processes in both natural and agricultural systems. Allelochemicals are a subset of secondary metabolites not required for metabolism (growth and development) of the allelopathic organism. Allelochemicals with negative allelopathic effects are an important part of plant defense against herbivory (i.e., animals eating plants as their primary food) (Fraenkel 1959; Stamp 2003).
The term allelopathy is from the Greek-derived compounds allelo and pathy (meaning "mutual harm" or "suffering") and was first used in 1937 by Austrian scientist Hans Molisch in the book Der Einfluss einer Pflanze auf die andere - Allelopathie (The Effect of Plants on Each Other) (Willis 2010). First widely studied in forestry systems, allelopathy can affect many aspects of plant ecology, including occurrence, growth, plant succession, the structure of plant communities, dominance, diversity, and plant productivity. Initially, many of the forestry species evaluated had negative allelopathic effects on food and fodder crops, but in the 1980s research was begun to identify species that had beneficial, neutral, or selective effects on companion crop plants (Table 1). Early research grew out of observations of poor regeneration of forest species, crop damage, yield reductions, replant problems for tree crops, occurrence of weed-free zones, and other related changes in vegetation patterns. Our purpose here is to introduce the concept of allelopathy, to cite specific examples, and to mention potential applications as an alternative weed management strategy.
Nature of Allelopathy
Commonly cited effects of allelopathy include reduced seed germination and seedling growth. Like synthetic herbicides, there is no common mode of action or physiological target site for all allelochemicals. However, known sites of action for some allelochemicals include cell division, pollen germination, nutrient uptake, photosynthesis, and specific enzyme function. For example, one study that examined the effect of an allelochemical known in velvetbean, 3-(3',4'-dihydroxyphenyl)-l-alanine (l-DOPA), indicated that the inhibition by this compound is due to adverse effects on amino acid metabolism and iron concentration equilibrium.
Allelopathic inhibition is complex and can involve the interaction of different classes of chemicals, such as phenolic compounds, flavonoids, terpenoids, alkaloids, steroids, carbohydrates, and amino acids, with mixtures of different compounds sometimes having a greater allelopathic effect than individual compounds alone. Furthermore, physiological and environmental stresses, pests and diseases, solar radiation, herbicides, and less than optimal nutrient, moisture, and temperature levels can also affect allelopathic weed suppression. Different plant parts, including flowers, leaves, leaf litter and leaf mulch, stems, bark, roots, soil, and soil leachates and their derived compounds, can have allelopathic activity that varies over a growing season. Allelopathic chemicals or allelochemicals can also persist in soil, affecting both neighboring plants as well as those planted in succession. Although derived from plants, allelochemicals may be more biodegradable than traditional herbicides, but allelochemicals may also have undesirable effects on non-target species, necessitating ecological studies before widespread use.
Selective activity of tree allelochemicals on crops and other plants has also been reported. For example, Leucaena leucocephala, the miracle tree promoted for revegetation, soil and water conservation, and livestock nutrition in India, contains a toxic, non-protein amino acid in its leaves that inhibits the growth of other trees but not its own seedlings. Leucaena species have also been shown to reduce the yield of wheat but increase the yield of rice. Leachates of the chaste tree or box elder can retard the growth of pangolagrass but stimulate growth of blueste m, another pasture grass. Many invasive plants may have allelopathy as a feature for their ecological success. One study in China found that 25 out of 33 highly noxious weeds screened had significant allelopathic potential.
Time, environmental conditions, and plant tissue all factor into variations in allelochemical concentrations in the producer plant. Foliar and leaf litter leachates of Eucalyptus species, for example, are more toxic than bark leachates to some food crops. The allelopathic potential of mile-a-minute vine (Ipomoea cairica) is significantly greater at higher environmental temperatures. One study indicated that soil biota reduced the allelopathic potential of sticky snakeroot (Ageratina adenophora). Red fescue infected by a fungal endophyte produced more allelochemi
อัลลีโลพาทีคืออะไรอัลลีโลพาทีอ้างถึงผลประโยชน์ หรือเป็นอันตรายของพืชหนึ่งในพืชอื่น พืชและวัชพืช ชนิด จากรุ่น biochemicals, allelochemicals จากชิ้นส่วนของพืชโดยละลายเรียกว่า ราก exudation, volatilization แยกส่วนประกอบของสารตกค้าง และกระบวนการอื่น ๆ ในระบบธรรมชาติ และเกษตร Allelochemicals เป็นชุดย่อยของ metabolites ที่ไม่จำเป็นสำหรับการเผาผลาญ (เจริญเติบโตและการพัฒนา) ของสิ่งมีชีวิต allelopathic รอง Allelochemicals กับ allelopathic กระทบเป็นส่วนสำคัญของพืชป้องกัน herbivory (เช่น สัตว์กินพืชเป็นอาหารหลัก (Fraenkel 1959 แสตมป์ 2003)The term allelopathy is from the Greek-derived compounds allelo and pathy (meaning "mutual harm" or "suffering") and was first used in 1937 by Austrian scientist Hans Molisch in the book Der Einfluss einer Pflanze auf die andere - Allelopathie (The Effect of Plants on Each Other) (Willis 2010). First widely studied in forestry systems, allelopathy can affect many aspects of plant ecology, including occurrence, growth, plant succession, the structure of plant communities, dominance, diversity, and plant productivity. Initially, many of the forestry species evaluated had negative allelopathic effects on food and fodder crops, but in the 1980s research was begun to identify species that had beneficial, neutral, or selective effects on companion crop plants (Table 1). Early research grew out of observations of poor regeneration of forest species, crop damage, yield reductions, replant problems for tree crops, occurrence of weed-free zones, and other related changes in vegetation patterns. Our purpose here is to introduce the concept of allelopathy, to cite specific examples, and to mention potential applications as an alternative weed management strategy.Nature of AllelopathyCommonly cited effects of allelopathy include reduced seed germination and seedling growth. Like synthetic herbicides, there is no common mode of action or physiological target site for all allelochemicals. However, known sites of action for some allelochemicals include cell division, pollen germination, nutrient uptake, photosynthesis, and specific enzyme function. For example, one study that examined the effect of an allelochemical known in velvetbean, 3-(3',4'-dihydroxyphenyl)-l-alanine (l-DOPA), indicated that the inhibition by this compound is due to adverse effects on amino acid metabolism and iron concentration equilibrium.Allelopathic inhibition is complex and can involve the interaction of different classes of chemicals, such as phenolic compounds, flavonoids, terpenoids, alkaloids, steroids, carbohydrates, and amino acids, with mixtures of different compounds sometimes having a greater allelopathic effect than individual compounds alone. Furthermore, physiological and environmental stresses, pests and diseases, solar radiation, herbicides, and less than optimal nutrient, moisture, and temperature levels can also affect allelopathic weed suppression. Different plant parts, including flowers, leaves, leaf litter and leaf mulch, stems, bark, roots, soil, and soil leachates and their derived compounds, can have allelopathic activity that varies over a growing season. Allelopathic chemicals or allelochemicals can also persist in soil, affecting both neighboring plants as well as those planted in succession. Although derived from plants, allelochemicals may be more biodegradable than traditional herbicides, but allelochemicals may also have undesirable effects on non-target species, necessitating ecological studies before widespread use.
Selective activity of tree allelochemicals on crops and other plants has also been reported. For example, Leucaena leucocephala, the miracle tree promoted for revegetation, soil and water conservation, and livestock nutrition in India, contains a toxic, non-protein amino acid in its leaves that inhibits the growth of other trees but not its own seedlings. Leucaena species have also been shown to reduce the yield of wheat but increase the yield of rice. Leachates of the chaste tree or box elder can retard the growth of pangolagrass but stimulate growth of blueste m, another pasture grass. Many invasive plants may have allelopathy as a feature for their ecological success. One study in China found that 25 out of 33 highly noxious weeds screened had significant allelopathic potential.
Time, environmental conditions, and plant tissue all factor into variations in allelochemical concentrations in the producer plant. Foliar and leaf litter leachates of Eucalyptus species, for example, are more toxic than bark leachates to some food crops. The allelopathic potential of mile-a-minute vine (Ipomoea cairica) is significantly greater at higher environmental temperatures. One study indicated that soil biota reduced the allelopathic potential of sticky snakeroot (Ageratina adenophora). Red fescue infected by a fungal endophyte produced more allelochemi
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