Allelopathy of decomposed maize straw products on three soil-born diseases of wheat and the analysis by GC-MS

QI Yong-zhi; ZHEN Wen-chao; LI Hai-yan

摘要

In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the ifeld. In order to investigate the alelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identiifed by gas chromatography-mass spectrometry (GC-MS). Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight ofRhizoctonia cerealiswere promoted at concentrations of 0.03, 0.06 and 0.12 g mL–1 and inhibited at concentration of 0.48 g mL–1 of the decomposed products. No signiifcant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth ofGaeumannomyces graminis was promoted at almost al concentrations except the highest one. Mycelial growth and spore germination ofBipolaris sorokiniana were signiifcantly inhibited by al concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration (0.03 g mL–1), with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by al the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL–1 of decomposed products after irrigation. However, the incidence rates and disease indexes were signiifcantly increased by 0.12, 0.24 and 0.48 g mL–1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-al were signiifcantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn’t change, signiifcantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the alelochemicals identiifed in straw decomposed products contained p-hydroxybenzoic acid (9.21%), dibutyl phthalate (6.94%), 3-phenyl-2-acrylic (5.06%), 4-hydroxy-3,5-dimethoxybenzoic acid (2.26%), hexanoic acid (1.73%), 8-octadecenoic acid (1.06%), 3-(4-hydroxy-3-methoxy-phenyl)-2-propenoic acid (1.04%), 4-hydroxy-3-methoxy-benzoic acid (0.94%) and salicylic acid (0.94%).

Allelopathy of decomposed maize straw products on three soil-born diseases of wheat and the analysis by GC-MS

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