Abstract:
The present study was conducted to assess the allelopathic effect of leaf and bark aqueous extracts of
Robinia pseudoacacia on germination and growth of some important food crops of the Garhwal Himalayas
viz. Triticum aestivum,
Hordeum vulgare, Lens culinaris and
Brassica rapa in laboratory and pot culture experiment. Different leaf and bark aqueous extracts (5%, 10%, and 15%) were prepared by soaking 25g, 50g and 75g of dry leaves and bark powder in 500mL of distilled water for 24 hours at room temperature and the resultant leaf and bark extracts were used to irrigate the seeds of various test crops. The results revealed that in laboratory conditions the concentration dependent significant inhibitory effect of all the concentrations of aqueous leaf extracts on germination, root length and shoot length of all the test crops except in
Hordeum vulgare where, the stimulatory effect of all the concentrations of leaf extract was observed in shoot length. Among all the test crops
Lens culinaris was found most sensitive with (41.6%) germination and root length (2.1 cm) in the seeds treated with 15% concentration of leaf extract as compared to control having germination (72.3%) and root length (7.2 cm). Similarly the maximum reduction by the 15% concentration of leaf extract was noticed in the shoot length of
Brassica rapa (5.5 cm) as compared to control (9.1cm). The 15% bark extract showed the maximum inhibitory effect on the germination of
Hordeum vulgare where germination percentage was reduced (48.0%) as compared to control (81.6%). Similarly, the maximum reduction in root length (2.7 cm) and shoot length (2.1 cm) as compared to control with root length (7.2 cm) and shoot length (6.7 cm) was observed in
Lens culinaris by 15% bark extract. In pot culture experiment
Hordeum vulgare was most sensitive with respect to germination percentage (39.2%) in 15% leaf extract as compared to control (77.0). While in root length maximum inhibitory effect was recorded in
Brassica rapa (3.4 cm) by 5% leaf extract as compare with control (4.2 cm). In general the non-significant stimulatory effect of all the concentrations of leaf extract was observed in all the test crops whereas, in
Lens culenaris the effect was significant stimulatory with shoot length (19.5cm) in 15% concentration as compared to control (19.0 cm).
Similarly 15% bark extract, performed maximum reduction in
Brassica rapa where the germination percentage was significantly reduced down (40.7%) as compare with control (77.5%). However, the effect of all the concentrations of bark extract showed non-significant effect on root length and shoot length of all the test crops. Therefore, to reduce allopathic effect on all the test crops
viz., Triticum aestivum,
Hordeum vulgare, Lens culinaris and
Brassica rapa it is advised to remove the fallen leaves and bark from the field.