Effect of three plant extracts on germination, vigour index and fungal infections of six soybean varieties (Glycine max L.) cultivated in Cameroon

Soybean seeds are affected by numerous seed-borne fungi. Seed treatment is an essential strategy for protecting plants against these fungi while improving germination rates, seedling vigour and reducing infections. This study aims to improve soybean productivity by treating seeds with plant extracts prior to sowing. Seeds of six soybean varieties were collected at the Institute of Agricultural Research for Development (IRAD). These seeds were treated separately with the three aqueous extracts of Chenopodium ambrosioides, Cestrum nocturnum and Callistemon viminalis at concentrations of 25, 50 and 75 mg/ml for six hours. Seeds were then placed in Petri dishes to collect data on germination percentage, vigour index and infection percentage. The results show that seeds of the SC Signal variety treated with Chenopodium ambrosioides extract at 75 mg/ml exhibited a germination rate of 95%, an infection rate of 1.67% and a vigour index of 2150. In addition, all varieties from seeds treated with the different plant extracts showed a significantly p ≤ 0.05 higher germination percentage, a lower infection rate and a higher vigour index compared with plants from untreated seeds. These results suggest that the use of these plant extracts can reduce soybean seed infections and improve germination rate and plant vigour index. Based on the results obtained, we recommend using Chenopodium ambrosioides extracts at a concentration of 75 mg/ml, as well as the SC Signal variety for good seed germination and vigour while reducing fungal infections.