Evaluation of Inoculation Methods for Determination of Winter Wheat Resistance to Fusarium Head Blight

Abstract

One of the most severe winter wheat (Triticum aestivum L.) diseases is Fusarium head blight (FHB). It is believed that selection for resistance to FHB is better in high disease pressure environments, for which various methods of artificial inoculation are used. The standard spray method of artificial inoculation is believed to be technically demanding and labour intensive. Therefore, scattering Fusarium-infected maize stalks onto trial plots after wheat emergence is suggested as a suitable alternative. The aim of this study was to compare the mean values and heritability of the visual rating index (VRI) and the percentage of Fusarium-damaged kernels (FDK) between the two abovementioned methods of artificial inoculation and natural infection, and to determine the phenotypic correlations between the three methods for the studied traits. The achieved levels of VRI and FDK were comparable for the two methods of artificial inoculation and considerably lower under natural conditions. Heritability for VRI ranged over four years from 0.68 to 0.91 for the spray method, from 0.73 to 0.95 for the infected maize stalks, and from 0.26 to 0.65 for natural infection, whereas for FDK it ranged from 0.56 to 0.85, 0.38 to 0.83, and 0.11 to 0.44 for the three inoculation methods, respectively. The strong positive correlation between the two applied methods of artificial inoculation for studied traits suggests that scattering infected maize stalks could serve as a reliable supplement for the technically and labor-intensive spray method of artificial inoculation.

Diallel Analysis of Wheat Resistance to Fusarium Head Blight and Mycotoxin Accumulation under Conditions of Artificial Inoculation and Natural Infection

“…Therefore, the strength of correlations between the two infection conditions for FHB resistance traits should not be neglected. In the present study, this correlation was stronger for VRI (r = 0.86) than for FDK (r = 0.62), which is consistent with the study of Šarčević et al [32], who also reported stronger correlations for VRI than for FDK between the conditions of natural infection and artificial inoculation with F. graminearum, with correlation coefficients ranging from 0.39 to 0.86 and from 0.15 to 0.56, respectively. In the present study, DON and ZEN were strongly positively correlated with VRI (r = 0.91) and FDK (r = 0.96 and 0.91, respectively).…”

“…Under the conditions of artificial inoculation, the broad sense heritability was very high for all traits (h 2 b > 0.90), whereas it was slightly lower for VRI (0.86) and much lower for FDK (0.52) under the conditions of natural infection. Lower values of heritability under the conditions of natural infection were also reported by Šarčević et al [32]. Under the conditions of artificial inoculation, the heritability for VRI, FDK, and DON was higher in our study than in the studies of Miedaner et al [23], Fakhfakh et al [28], Ma et al [33], Larkin et al [34], and Zhang et al [35].…”

“…Knowing the extent of correlation between FHB resistance traits is important for optimizing the breeding efforts for FHB resistance. From a practical point of view, visual evaluation of FHB symptoms on spikes (VRI) is less laborious and time-consuming than evaluation of Fusarium-damaged kernels (FDK) and is preferred by breeders [32]. In the present study, a strong positive correlation was observed between VRI and FDK under the conditions of artificial inoculation (r = 0.93) and was of the higher magnitude compared to some previous studies, in which correlation coefficients between the two FHB ratings ranged from 0.54 to 0.89 [32,34,[39][40][41][42].…”

“…From a practical point of view, visual evaluation of FHB symptoms on spikes (VRI) is less laborious and time-consuming than evaluation of Fusarium-damaged kernels (FDK) and is preferred by breeders [32]. In the present study, a strong positive correlation was observed between VRI and FDK under the conditions of artificial inoculation (r = 0.93) and was of the higher magnitude compared to some previous studies, in which correlation coefficients between the two FHB ratings ranged from 0.54 to 0.89 [32,34,[39][40][41][42]. Compared to artificial inoculation, the correlation between VRI and FDK under natural infection was lower (0.73) in the present study.…”

“…According to Buerstmayr et al [43], FHB occurs unpredictably under natural conditions and the disease is not evenly spread across the field, confirming the need of artificial inoculation for a reliable FHB resistance evaluation. Hence, the resistance levels determined under natural conditions can serve as a good proof for the resistance levels determined by artificial inoculation [32]. Therefore, the strength of correlations between the two infection conditions for FHB resistance traits should not be neglected.…”