Allelopathic effect of Amaranthus spinosus Linn. on growth of rice and mustard

摘要

A study was conducted to evaluate the inhibitory effect of aqueous leaf extract of Amaranthus spinosus Linn. (family Amaranthaceae), an important medicinal plant, on growth activities of rice ( Oryza sativa L.) and mustard ( Brassica campestris L.) seedling. The growth parameters were significantly inhibited due to the activity of allelochemicals present in the weed. The germination of crop seeds as well as their root and shoot length were suppressed more than 50% with the treatment. Fresh weight (FW) of rice seedlings were reduced to 16.7 g, 16 g and 15 g with 1:20, 1:10 and 1:05 concentration as compared to 18.50 g of control. In case of mustard, there was 50% reduction in FW and 40% reduction in dry weight (DW) with the same concentration. Similar trend was also recorded for relative water content (RWC) where mustard plants showed a reduction up to 58%. Among the three enzymes studied, mustard was more sensitive to catalase and á- amylase and rice to peroxidase activity in terms of mUg-1FW. Similarly chlorophyll content was reduced to 50% for both test crops. Presence of phenols, ketones, flavonoids in the leaf leachate of A. spinosus suggest that the plant has allelopathic potentiality which might be responsible for the restricted growth activity of the crops. Comparative study revealed the inhibition of metabolic activity to be more in case of mustard than in rice and that the suppression was concentration depended. However, further research is necessary to confirm the presence of single compound responsible for this interaction.