Document Type : Short paper
Author
Yazd Agricultural and Natural Resources Research and Education Center, AREEO,Yazd, Iran
Abstract
Keywords
Main Subjects
Extended Abstract
Introduction
The production of greenhouse crops is crucial in Iran due to its dry, low rainfall climate. However, high investments in this field are hindered by a lack of proper management in controlling pests and plant diseases, leading to reduced productivity. Among greenhouse products, greenhouse cucumber is a significant agricultural product in the country. According to statistics from the Ministry of Agricultural-Jihad, greenhouse cucumber production exceeded 1.9 million tons, with Tehran province at 39.4%, southern Kerman province at 21.3%, Yazd province at 13.4%, and Isfahan province at 8.1% ranking as the top producers. The lack of proper plant disease management, particularly fungal diseases, results in severe crop losses, such as root and stem rot caused by Fusarium oxysporum f. sp. radicis-cucumerinum in greenhouse cucumbers annually. The rise in fungal diseases, especially in greenhouse crops, has led to excessive use of chemical pesticides, resulting in increased production costs, pathogenic resistance, environmental damage, and harm to the natural ecosystem. Additionally, the maximum residue limits of pesticides in agricultural products have negative effects on human and animal health, as well as on the export of agricultural products, causing irreparable damage to the country's economy, agricultural industry, and farmers' livelihoods. Biological control is an optimal method for managing plant diseases that aligns with environmental goals and poses less risk to human health and the environment. In recent years, biological control agents, such as non-pathogenic bacteria like Bacillus strains, have been utilized to reduce the use of chemical toxins due to their ability to produce fungal inhibitory compounds. This research compares Bacillus mycoides LUTUUS-AF1 (BmL) from Lotus Co. with Pars Bacil internal biological fungicide (BvP) based on Bacillus velezensis bacteria and an imported biological fungicide (SAS) based on Bacillus velezensis (BvB) bacteria to assess their antagonistic abilities in laboratory and greenhouse conditions.
Materials and Methods
First, the inhibitory power of these three samples against Fusarium oxysporum f. sp. radicis-cucumerinum was investigated through cross-culture in PDA medium in a completely randomized design with four replications. Next, under greenhouse conditions, the ability of these three samples to control Fusarium stem and root rot disease in a 50-day growth period on greenhouse cucumbers was evaluated through a factorial experiment in a completely randomized design with 3 factors and 3 replications. The studied factors were: 1- Treatments (Bacillus mycoides strain LUTUUS-AF1, Pars Bacil based on Bacillus velezensis, and an imported biological fungicide (SAS) based on Bacillus velezensis (BvB) bacteria), 2- Different concentrations of bacterial treatments (0, 0.1, 0.3, and 0.5% of the concentration of 1*109 cfu/ml for all three treatments with irrigation water), and 3- Application time of treatments (0, 96, and 192 hours).
Results and Discussion
The results showed a significant difference between the studied Bacillus species against the pathogen. Among the three samples, B. mycoides strain exhibited the highest inhibitory power at 48%, effectively controlling the growth of Fusarium fungus. The imported biological fungicide (SAS) and Pars Bacil treatments provided 30% and 29% inhibition against Fusarium fungi, respectively. In greenhouse conditions, the mortality rate in the control treatment was close to 70%. B. mycoides strain, at concentrations of 0.3% and 0.5% with three repetitions (0, 96, and 192 hours), demonstrated the best efficiency during the 50-day period, with disease incidence close to zero and no observed mortality in the plants. Despite a significant difference between B. mycoides and SAS, the latter at a concentration of 0.5% and three repetitions (0, 96, and 192 hours) yielded similar results. Both were significantly different from Pars Bacil, which showed the lowest mortality rate (approximately 8%) at a concentration of 0.5% and three repetitions.
Conclusion
Overall, due to the strong inhibitory effect of B. mycoides in both laboratory and greenhouse conditions, further research is recommended for the production and commercialization of this bacterium.
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