of Pinus sylvestris. The allelopathic activity is due to the highest phenolic accumulation. Also, there was higher phenolic content, and their variety in shoot extract was
compared to the root extract of plant species.
Emodin
Physcion
Two allelochemicals emodin and physcion (above figure) were detected from
various parts (rhizomes, aerial parts, and fallen leaves) of Polygonum sachalinense
Fr. Schm. [29].
Coumarins and their glucosides are abundant and commonly present phytochemicals in the plants. Families, namely, Apiaceae, Rutaceae, Asteraceae, and Fabaceae,
are known for the presence of coumarins. Some of the coumarins, scopoletin,
umbelliferone, and esculetin, are known for their allelopathic effect. Some of the
reports which support phytotoxic activity due to presence of coumarin are [30–33].
Imperatorin and psoralen are two other coumarins which show considerable allelopathic activity [34].
scopoletin
umbelliferone
Esculetin
2.2
Alkaloids
Many past and recent research reports revealed that alkaloids are also known for
their allelopathic effect. Caffeine, gramine, and nicotine show the allelopathic effect.
Caffeine is responsible for autotoxicity in coffee and tea plantations, while nicotine
affects the seed germination at higher concentration [35]. Phytotoxicity of gramine
on oat, wheat, rye, and weed Lolium rigidum was studied [36]. Rhazya stricta also
contain alkaloids with allelopathic activity [37].
caffeine
Gramine
Nicotine
Hordenine
446
A. Bachheti et al.
compared to the root extract of plant species.
Emodin
Physcion
Two allelochemicals emodin and physcion (above figure) were detected from
various parts (rhizomes, aerial parts, and fallen leaves) of Polygonum sachalinense
Fr. Schm. [29].
Coumarins and their glucosides are abundant and commonly present phytochemicals in the plants. Families, namely, Apiaceae, Rutaceae, Asteraceae, and Fabaceae,
are known for the presence of coumarins. Some of the coumarins, scopoletin,
umbelliferone, and esculetin, are known for their allelopathic effect. Some of the
reports which support phytotoxic activity due to presence of coumarin are [30–33].
Imperatorin and psoralen are two other coumarins which show considerable allelopathic activity [34].
scopoletin
umbelliferone
Esculetin
2.2
Alkaloids
Many past and recent research reports revealed that alkaloids are also known for
their allelopathic effect. Caffeine, gramine, and nicotine show the allelopathic effect.
Caffeine is responsible for autotoxicity in coffee and tea plantations, while nicotine
affects the seed germination at higher concentration [35]. Phytotoxicity of gramine
on oat, wheat, rye, and weed Lolium rigidum was studied [36]. Rhazya stricta also
contain alkaloids with allelopathic activity [37].
caffeine
Gramine
Nicotine
Hordenine
446
A. Bachheti et al.