Suppression of seed rot and preemergence of chickpea by seed treatments with fluorescent pseudomonads in Iran.
Species of Pythium isolated from rotted chickpea seeds and damped-off seedlings and chickpea soils at experimental field of Agriculture faculty of Tehran University in Karaj area that caused seed rot and preemergence damping-off of chickpea were Pyhium ultimum var. ultimum. One of the most important of soilborne fungal pathogens of the chickpea in Iran is seed rot and preemergence damping-off caused by Pythium ultimum Trow. Consequently, growers can expect as much as > 80% reduction in stand and yield if measures are not taken to control Pythium. Currently, most commercial seeds of chickpea are treated with pesticides. Fluorescent pseudomonads applied to seed are known to reduce soilborne diseases of chickpea caused by Pythium spp. In this study rotted chickpea seeds and diseased seedlings and soil samples were collected from experimental field in Karaj. Soils and roots used as sources of bacteria were collected from field. Fluorescent pseudomonads were isolated by plating samples on S1 and King's Medium B (KMB). Bacteria were preserved in 0.1 M MgSO4 for long-term storage; and NAG (containing 2% glucose) slants and plates at 4 degrees C short-term storage. Of 20 fluorescent pseudomonads isolated on S1 medium, 2 isolates selected for next tests. All strains significantly increased emergence as compared to the infested control in greenhouse trial; isolate Pf-4 consistently provided the best protection against Pythium. Seedling emergence from all bacteria seed treatments was statistically lower than the chemical treatments. All strains significantly increased fresh weight of chickpea as compared to the infested control in greenhouse trial. Seed treatment with metalaxyl were statistically better than captan in sterilized soil. In nonsterilized soil collected from the field artificially infested with P. ultimum, all strains significantly increased fresh weight of chickpea as compared to the infested control in greenhouse trial. Seedling emergence from seed treatment with isolate Pf-1 was the least effective treatment on fresh weight of chickpea in nonsterilized soil infested with P. ultimum. Seed treatment with captan was statistically better than metalaxyl in nonsterilized soil.
Ahmadzadeh
M
M
Faculty of Agriculture, Plant Protection, Tehran University, Department of Plant Protection, Karaj, Iran. ahmadz@ut.ac.ir
Sharifi-Tehrani
A
A
D029863:Cicer / Q000382:microbiology / Q000502:physiology*; D005453:Fluorescence; D007492:Iran; D010935:Plant Diseases / Q000382:microbiology*; D011549:Pseudomonas / Q000302:isolation & purification / Q000502:physiology*; D012639:Seeds / Q000382:microbiology* / Q000502:physiology