The Research Of Onion Fungal Disease During Storage Period In Gansu Province

Onion dry rot and Penicillium are two important diseases of onion storage in Gansu province, which restricted the storage period and quality of onion severely. To clear the pathogens and dominant species, the method of r DNA-ITS-PCR was used and identified with typical mold symptoms. The results showed that: 1 The symptoms and pathogens of Fusarium dry rot on onion bulbsThe disease could occur throughout the storage period of onion bulb, early onset of petals were faded yellow, gradually extended from the outside to the inside of the bulb, severe atrophy, dry, white mycelial growth form disease area. using the method of morphology and ITS sequence analysis, the pathogens were identified as Fusarium oxysporum Schlechtendahl emend.Snyder & Hansena and Fusarium proliferatum(Matsushina)Nirenberg, The dominant species were Fusarium oxysporum Schlechtendahl emend.Snyder & Hansena. Fusarium proliferatum(Matsushina) Nirenberg was first reported on onion bulb. 2 The biological characteristics of onion dry rot pathogensTwo species of Fusarium could grow in the range 5-40℃, both of them optimal growth temperature were 25℃, two kinds of Fusarium growth were relatively slow under 5℃ and 40℃. Using sucrose as the carbon source of the medium, the two Fusarium mycelial were all growth well, followed by glucose. Two species of Fusarium mycelial on containing mannitol and soluble carbon source medium significantly were growth slower than in the other medium carbon source. Sodium nitrate significantly promoted the growth of Fusarium oxysporum hyphae, Ammonium sulfate significantly promoted the growth of Fusarium proliferatum hyphae, But the urea medium had significant inhibition of two Fusarium mycelial growth. 3 The toxicity test of onion dry rot pathogensEight kinds of fungicides had certain inhibited Fusarium oxysporum and Fusarium proliferatum mycelial growth, inhibition rate was positively correlated with drug. The inhibitory rate and the drug concentration were positively correlated. 43% tebuconazole had best inhibitory effected Fusarium oxysporum and Fusarium proliferatum mycelial growth, the EC50 was 0.4μg/L、0.7μg/L. 4 Onion Penicillium disease symptoms and pathogensThe disease could also occur in the all onion storage period, a large number of Penicillium colony were attached to the outer layer of onion bulb, effected quality and shorten the storage time of onion. using the method of morphology and ITS sequence analysis, the pathogens were identified as Penicillium crustosum 、Penicillium polonicum、 Penicillium viridicatum and Penicillium glabrum. 5 the biological characteristics of Onion Penicillium disease pathogensFour species of Penicillium could grow in the range 5-40℃, all of them optimal growth temperature were 25℃, Four species of Penicillium mycelial growth were relatively slow under 5℃ and 40℃. Using Glucose and sucrose as the carbon source of the medium, the Four species of Penicillium mycelial were all growth well; without addition of carbon source medium, the four kinds of Penicillium mycelium had different inhibition degrees. Glycine as a nitrogen source had significant promoted four kinds of Penicillium mycelia growth, Using urea as nitrogen source were obviously inhibited the mycelia growth of four Penicillium species. Different types of media also had certain effected on mycelium growth of four penicillium species. 6 The toxicity test of onion Penicillium disease pathogensEight kinds of fungicides had certain inhibited four kinds of Penicillium mycelia growth, inhibition rate were positively correlated with drug. The inhibitory rate and the drug concentration was positively correlated. 43% tebuconazole had the best inhibitory effect in four kinds of Penicillium mycelia growth, the EC50 was 2.4μg/L、2.7μg/L、4.6μg/L、3.7μg/L.