Screeining Of Biocontrolagainst Corn Stalk Rot And Studies On The Application Technology

This study Sreened biocontrol bacterial to corn stalk rot, studied the application technology of the biocontrol bacterial, and identified them and studied some biological characteristics of them.1193 bacteria were isolated from 146 kind of plant samples collected from Xuchang Pindingshan and Xinxiang in Henan province, bacteria G28-6,K3-3 and K18-5 were selected because they not only have ability to inhibit the mycelial growth of the Fusarium graminearum, Pythium graminicola and Pythium inflatum,but also have control effect to the corn stalk rot in pot experiment in greenhouse and can promote seed germination and root development.In order to explore the application of technology of the biocontrol G28-6, K3-3 and K18-5 of, we study treatment method, treatment concentration, treatment period, treated separately and mixe of the three biocontrol to the corn stalk rot. In seed soaking treatment, biocontrol G28-6, K3-3 and K18-5 use 108cfu/ml and soak 8 hours, the control effect is better; In perfusion treatment , perfusion twice treatment is better than perfusion once; Mixed treatment is better than single treatment, in the mixed treatments G28-6 and K3-3 have significant control effect to the corn stalk rot, its control effect reach 64.7%.besides, the three biocontrol have a good colonization on corn root and rhizosphere soil, in field trials, the colonization density on rhizosphere soil exceed 3.0×10~4 cfu / g soil and the colonization density on maize root exceed 9.0×10~5 cfu / g root after sowingthirty days, the colonization density on rhizosphere soil exceed 2.0×10~4 cfu / g soil and the colonization density on maize root exceed 3.5×10~4 cfu / g root after sowing sixty days.By morphological, physiological and biochemical characteristics and 16SrDNA sequence homology analysis, three of biocontrol agents were identified. G28-6 was Gram-negative bacteria, facultative anaerobic, with exercise, identified as Pseudomonas aurantiaca, K3-3 was Gram-negative bacteria, facultative anaerobic with exercise, identified as Pseudomonas chlororaphis, K18-5 was Gram-positive bacteria, facultative anaerobic, with exercise, identified as Paenibacillus polymyxa. Some biological characteristics were studied. G28-6 suitable growth phase is 20-48h, the optimum growth temperature is 28℃, the suitable medium pH is 6.5-8; K3-3 suitable growth phase is 20-48h, the optimum growth temperature is 28℃, the suitable medium pH is the 6-9; K18-5 suitable growth phase is 20-60h, the optimum growth temperature is 28℃, the suitable medium pH is 5-7.5. Three biocontrol can use a variety of carbon and nitrogen sources.