Biocontrol of Parthenium for regenerating lost biodiversity

Prof N Irabanta Singh
(Contd from previous issue)
Seed germination inhibition of 88% under the influence of 9 day leaf leachate of Cassia tora was reported (Singh and Riti, 2002).
Leachates of the selected plants of different immersion period and concentration showed variable seedling growth response of Parthenium.
At 100% concentration leaf leachate of Cassia tora, 76.19% and 71.41% reduction in shoot and root length in 4 day old leachates; 78.26% and 79.31% reduction in shoot and root length in 8 day old leachates and 80% and 79.31% reduction in shoot and root length in 12 day old leachates respectively has been recorded.
Thus, the study revealed that the Cassia tora phytoextract could be used as a possible bioherbicides for the control of Parthenium.
Control of Parthenium by Cassia tora in microplot field condition
The effective botanical agents against Parthenium were selected from the above experimented result and trials were made in microplot field condition. The experiment was conducted in the Life Sciences Department, Manipur University in controlled field condition in 2x2 m microplots size in randomized complete block design. Parthenium and Cassia tora were grown in five combinations i.e. 50:25, 50:50, 50:75, 50:100 and 50:125 ratio plants. Plot of Parthenium alone was maintained as control. Observations were recorded after 3 months from DAS on average plant height, number of branches and number of flowers per plant during the flowering stage of Parthenium and dry plant biomass.
The experimental finding shows that the height of the Parthenium was found decreased as the ratio of Cassia tora to Parthenium increase. In 50:25 Parthenium to cassia tora ratio plot, the height of the Parthenium was not much effected but as the population ratio of Cassia tora increase the reduction percent of Parthenium height were 25.22%, 54%,71.92%, 82.01% and 90.25% at 50:25, 50:50, 50:75,50:100, 50:125 respectively as compared to control plot.
Cassia fora reduced the number of branch of Parthenium in the entire treated plot. Maximum number of main branch was observed in control plot with 8.6 in number and minimum was observed in 50:125 ratio plots with 1.4 in number in Cassia tora treated plot respectively.
The reduction percent of number of branch per parthenium plant was 26.92%, 42.31% ,53.85%, 57.69% and 73.08% in Cassia tora treated plot at 50:25, 50:50, 50:75,50:100, 50:125 ratio respectively as compared to control plot.
The number of flower per Parthenium plant was very much affected with Cassia tora treatment. In 50:25 ratio treatments the number of flower per Parthenium plant was reduced to 94.41% in Cassia tora treated plot respectively as compared to control plot. Cent percent inhibition of flower production per Parthenium plant was observed in 50:125 ratio Cassia tora plot.

(To be contd)