Allelopathic effects of different phenological stages of Cassia occidentalis L. on Parthenium hysterophorus L. Narsingh Bahadur Singh*, Sanjay Kumar, Deepti Singh and Kavita Yadav

The effect of leachates of different phenological stages of Cassia occidentalis L. on Parthenium hysterophorus L. was studied. Seed germination, radicle length, plumule length and fresh and dry weight of Parthenium were recorded. Pigments and protein contents were also measured to evaluate relation between biochemical and biophysical parameters of Parthenium under stress. The leaf leachate of Cassia in different developmental stages and pod and seed leachates exhibited varying effect. The Cassia leachate obtained from the leaves of vegetative and flowering stages was more phytotoxic. It caused maximum inhibition of germination and seedling growth of Parthenium.  Biochemical parameters, viz. protein and chlorophyll were also influenced. Root and shoot growth and fresh and dry weight decreased in almost all the treatments. The inhibition of germination was in order of vegetative > flowering > fruiting > fruit ripening > pod > seed while 25 and 50% concentrations of seed leachate stimulated the germination. The 100% concentration of leaf leachate from vegetative stage completely inhibited the germination while highest concentration of leaf leachate from vegetative, flowering, fruiting and fruit ripening stages caused the death of the plants. The average inhibition of parameters of seedlings in pot culture was in order of fruiting > vegetative > fruit ripening > flowering > pod > seed.