Evaluation of wheat genotypes resistance to Fusarium head blight in Paraguay

Abstract

Fusarium head blight (FHB), or scab, caused by a Fusarium spp. complex, is an important wheat disease in Paraguay. Among the strategies used to control it, the genetic resistance is considered highly efficient and cost effective. This study aimed to evaluate and compare the effects of F. graminearum on six wheat genotypes, including two comparison varieties, in two seeding dates. The genotypes were artificially inoculated in the spike, at the flowering stage, by injecting a pool of four pathogenic F. graminearum isolates. The FHB development was evaluated by scoring the disease incidence and severity, percentage of diseased spikelets and damaged kernels, as well as using the area under the disease progress curve. Besides the kernel infection, its impact on the development of mycotoxins (deoxynivalenol) and interactions with the genotypes were also evaluated. The results identified an advanced breeding line (Lin 84) with a resistance level to FHB comparable to that of the universally known resistance sources (Sumai 3 and Frontana). The other three genotypes (Caninde 11, Caninde 12 and Caninde 21), in spite of presenting a higher grain yield potential, were evaluated as moderately susceptible to susceptible. These results suggest that, although it is possible to transfer the FHB resistance to a higher agronomic type, combining such resistance with a higher grain yield potential remains an ongoing challenge.

KEYWORDS: Fusarium graminearum, Triticum aestivum, genetic resistance, scab.