Evaluation of resistance to aphids and barley yellow dwarf virus in 33 oat germplasms

Barley yellow dwarf virus (BYDV) is one of the main oat diseases in China. The present study aimed to confirm the resistance of different oat cultivars to aphids and barley yellow dwarf virus. Using fuzzy synthetic assessment and through observations under field conditions, the resistance of 33 oat germplasm resources against naturally inoculated viruliferous aphids and BYDV was evaluated in 2015–2017. The number of aphids and disease severity at the filling stage were investigated, the ratio of rating scale infested by aphid and average severity were calculated, and resistance to aphids and BYDV was examined. The results showed that eight oat cultivars, including Lingdang oat, Qingyongjiu 420, Qingyongjiu 119, Baiyan No.1, Nongda 360, MN10253, Ningyou No.1, and Zhongsui, showed resistance to aphids over the three years, accounting for 24.24% of the tested cultivars. Jim 1, Huawan No.6, and MN11213 cultivars were consistently sensitive to aphids over the three years, accounting for 9.09% of the tested cultivars. Ten of the tested oat cultivars were resistant to BYDV, including Lingdang, Duji, Nongda 360, Qingyongjiu 119, Qingyongjiu 260, Qingyongjiu 420, Keyan No.1, Qingyongjiu 355, Ningyou No.1, and Qingyongjiu 9, accounting for 30.3% of the tested cultivars. Dingyou NO.4 and Jim 1 were consistently sensitive to BYDV over the three years, accounting for 6.06% of the tested cultivars. Lingdang oat, Qingyongjiu 119, Qingyongjiu 420, Nongda 360, and Ningyou No. 1 were the optimal germplasm resources, as they were the most resistant to aphids and BYDV among the 33 test resources during the three-year period. Jim 1 was the only sensitive variety to both aphids and BYDV over the three years. The ratio of aphid numbers was significantly positively correlated with the severity of BYDV disease. Baiyan No. 15 was an outlier cultivar and was easily infected by BYDV. In this study, the resistance of oat germplasm resources to aphids and BYDV was studied, and the resistant oat germplasms were identified. This has extremely important guiding significance for the selective breeding of oats against pests and diseases.