Allelopathic effect of cleavers (Galium aparine) on germination and early growth of wheat (Triticum aestivum)

Aqueous extracts were prepared from the roots, stem, leaves and fruit of mature cleavers (Galium aparine) plants and soil taken from its field, to determine the allelopathic effects on germination and seedling growth of wheat (Triticum aestivum L.) in the laboratory. At 20°C, time taken for 50% germination and reduction in germination index was maximum, whereas, at 15°C, germination time was maximum. The aqueous extracts reduced the root and shoot length and biomass of wheat seedlings by 34.0 to 67.9%, 10.4 to 61.6% and 16.5 to 38.0%, respectively. The fruit extract of G. aparine proved most harmful to root and shoot length and seedling biomass of wheat. However, root extract increased the shoot dry weight (32.4%) and seedling biomass (11.4%) over control. Soil beneath the G. aparine plants also significantly reduced the shoot length, dry weight and seedling biomass but increased the root dry weight of wheat seedlings. Thus soil incorporated plant residues of this weed may have broad implications for the growth of succeeding crop.