Exhibition of allelopathy by Parthenium hysterophorus L. in Agroecosystems

Abstract

The yield and biomass of five pulse crops namely, Cyamopsis tetragonoloba, Phaseolus aureus, Phaseolus mungo vars. MI-1 Pantu-19 and Vigna umbellata when grown in soil earlier infested with Parthenium hysterophorus were greatly reduced. The seed germination parameters and relative growth rate of the crops were also reduced. The soil inhabited with P. hysterophorus was not rendered poor in its available macronutrients especially nitrogen, phosphorus and potassium. On the contrary, it was enriched. However, the texture, pH and conductivity of the P. hysterophorus inhabited soil were almost the same as that of the control (about 100 m away). On the other hand, the amount of soil chemicals was found to be maximum in P. hysterophorus inhabited soil sampled from all the three depths (0-7, 14-21 and 28-35 cm depths), compared to respective soil layers from the control. The bio-efficacy studies of the soil chemicals conducted on a representative plant Phaseolus aureus, points to its inhibitory nature. Not only the different germination parameters were affected but the mature plants too showed reduced cell survival, contents of water and chlorophyll compared to the control. Thus, the chemicals accumulated in the soil infested with P. hysterophorus, qualify to be called as allelochemicals.