Neran Salem Aljarah
Abstract: The study was conducted to evaluate the activity of the fungus Metarhizium sp., as a biocontrol agent, against Pythium aphanidermatum causative agent of cucumber seedlings damping off in Agriculture College Baghdad University. Results showed a high significant increase in lateral root 13.7/ seedling and root length 9.3 cm in seedling grown on water agar (WA) inoculated with Metarhizium sp. After 4 days of cultivation compared with 7.8 lateral root / seedling and 4.3cm length in control (without Metarhizium sp.). More intense of hairs on the main root in seedling on water agar with Metarhizium sp. compared with control were observed. The increasing of root formation was found associated with high inhibition of P. aphanidermatum as proved by the reduction of mycelium growth on PDA compared with control. The presence of Metarhizium sp. with P. aphanidermatum in the soil cultivated with cucumber plants induced a significant increase in healthy seedling, 86.7 and 66.7 % after 7 and 21 days of cultivation respectively compared with 50 and 40 % in control respectively. The increase in healthy seedling was found associated with an increase in plant dry weight. The dry weights of root and foliage were attained to 0.56 and 0.89 g/ plant in pots inoculated with Metarhizium sp. and P. aphanidermatum respectively compared with 0.31 and 0.45g/plant respectively in control after 30 days of cultivation.
Keywords: Metarhizium sp, Pythium aphanidermatum, biocontrol agent, cucumber plants