Preliminary Investigations on the Control of Yam (dioscorea Rotundata Poir) Tuber Rot Through Nanoscience

In vitro and in vivo experiments were conducted to evaluate the bioactivity of nanoparticles of silver and neem (AgNeemnano) solution on some organisms that cause yam rot. In the in vitro study, organisms were isolated from a decaying yam tuber and identified as Fusarium moniliforme and Lasiodiplodia theobromae. The organisms were cultured in Sabouraud dextrose agar. With a cork borer of diameter 8 mm, cups were made at the centre of each of the agar plates, and then 0.05 ml AgNeemnano solution in varying concentrations (28.40, 56.81, 113.63, and 227.27 mg/ml) was aseptically introduced into the cups starting from the lowest to the highest concentration. The plates were incubated at 35 degrees C for 48 h, and the zones of inhibition were determined. In the in vivo study, sterile yam slices, each weighing approximately 12.6 g, were dipped into each level of AgNeemnano solution for 3 min and thereafter inserted into the Petri dishes containing each of the organisms. The minimum inhibition concentration ( MIC) of the AgNeemnano that inhibited the mycelial growth of F. moniliforme was 0.8 mg/ml, while the MIC of the AgNeemnano for L. theobromae was 0.5 mg/ml. The sterile yam slices dipped in the AgNeemnano solution and later inserted into cultured organisms were not attacked by the rot-causing organisms.