Allelopathc Effects of Medicinal Plant Species on Seed Germination and Seedling Growth of Wheat Varieties

Allelopathic effect of three medicinal plant species viz. Costus speciosus, Tinospora cordifolia and Coleus forskohli was examined on seed germination and seedling growth of four (Pusa gold, HD2733, VL-914, RSP 561) popular wheat (Triticum aestivum L.) Varieties. The aqueous leaf extracts reduced the seed germination and seedling growth of wheat. The value of percent reduction in seed germination and relative germination index (GRI), inhibitory effect of different leaf extracts was maximum in susceptible varieties (VL-914& RSP 561) followed by tolerant varieties (Pusa gold & HD2733). The root and shoot length, root and shoot dry weight declined with the increase in the concentration of the leaf extracts of all the three medicinal species. Leaf extract of all three species showed inhibitory effect on sugar and protein and a stimulatory effect on total amino acid contents of the wheat seedling. The results indicated that the allelopathic effect of leaf extracts of Coleus forskohlii was maximum in terms of all physiological and biochemical parameters.