冬季灌水对土壤中向日葵菌核的活力及其致病力的影响

Effects of winter broad irrigation on the vigor and pathogenicity of sunflower sclerotia in soils

为明确内蒙古巴彦淖尔市河滩地向日葵菌核病发生轻的原因,在内蒙古农业大学教学农场模拟了巴彦淖尔市河滩向日葵地块的种植条件即对土壤中的向日葵菌核进行了冬季大水漫灌处理,并在次年春天对冬灌水处理后土壤中菌核的活力、草酸分泌量、多聚半乳糖醛酸酶(polygalacturonase,PG)的活性以及致病力进行了测定。结果表明,灌水处理后土壤中菌核萌发率为46%,比未灌水处理的对照降低了27%;草酸分泌量为50.94μg/mg,PG活性为14.82 U/mg,均显著低于对照。冬灌水处理后的菌核萌发后在离体叶片上接种病斑大小仅为0.69cm,显著低于未经冬季灌水处理的1.29 cm。2012和2013年的向日葵植株活体接种试验结果表明,用冬灌水处理后的菌核接种后发病株率分别为10.67%和18.37%,显著低于未经灌水但混有菌核的处理。表明冬季灌水处理能够降低土壤中菌核来年对向日葵的致病力,从而降低向日葵菌核病的发病程度。

To unravel the reasons why sunflower white mold caused by Sclerotinia sclerotiorum is much less severe in fields along Yellow River bank in Bayannaoer region,the river flooding condition of sunflower fields in the river bank of Bayannaoer were mimicked under the farm conditions in winter. The germination rate,oxalic acid secretion,polygalacturonase activity( PG) and pathogenicity of the treated sclerotia were measured. The results showed that germination rate of water-treated sclerotia was 46%,compared with the untreated control( 27%). Oxalic acid value was 50. 94 μg /mg and PG enzyme activity was 14. 82 U /mg. The average lesion size on the detached leaves was only 0. 69 cm,much smaller than that of the control. The infection rates of living plants were 10. 67% and 18. 37% in 2012and 2013,respectively. These results indicated that winter broad irrigation treatment could be used as one of agricultural practices to reduce the severity of sunflower white mold in sunflower fields.