Probing the allelopathic hierarchy of a monocot weed -Desmostachya bipinnata versus two dicot weeds Parthenium hysterophorus and Alternanthera sessilis using their leaf leachates on germination behaviour of Senna occidentalis seeds.

Abstract

An endeavour was made to study the hierarchy of allelopathic   potential   of   three   selected weeds of West Bengal viz- Desmostachya bipinnata (L.) Stapf (Poaceae), Parthenium hysterophorus L. (Asteraceae), Alternanthera sessilis (L.) R. Br. ex DC. (Amaranthaceae), on the seeds of weed species Senna occidentalis (L.) Link, (Fabaceae), the chosen bioassay material in this case. Germination behaviour indices of Senna seeds was measured in terms of percentage of seed germination, T50, TTC stainability of seeds and speed of seed germination exposed to [1:5, 1:10 and 1:20 (w/v)] of leaf leachate concentrations of the weeds respectively. Obtained data show that a higher concentration of leachate is directly proportional to the resistance to the percentage and speed of seed germination and seed respiratory activities as indicated by reduced stainability with TTC along with increase of the T50 values. Observed data is good fit and significant and help to establish the hierarchy of allelopathic potential of the weeds as- Alternanthera < Parthenium < Desmostachya posing questions on whether in general monocotyledonous weeds like Desmostachya bipinnata are more allelopathically vigorous than other dicotyledonous weeds including Parthenium hysterophorus and Alternanthera sessilis.