ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 106, No. 3 (2019), p. 249–256
DOI 10.13080/z-a.2019.106.032

Do black dots on wheat grains have an impact on deoxynivalenol accumulation?



A study, conducted at Lithuanian Research Centre of Agriculture and Forestry in 2016 and 2017, addressed the issue of black dots on common wheat (Triticum aestivum L.) grain, which had not been widely spread in Lithuania before 2016. This problem has provoked a lot of discussion among grain growers, purchasers, processors, scientists and consumers. According to the quality requirements for purchase and supply of wheat grain, visually estimated Fusarium-damaged grain (causal agents – fungi of Fusarium genus) in a sample must not exceed 1%. The objective of the study was to ascertain which of the Fusarium species cause black dots on wheat grain, to determine and compare deoxynivalenol (DON) contamination levels in the grain with different visually estimated Fusarium damage severity, and to verify whether black-dotted grain can be stored without posing the risk of increasing DON concentration. Black dots on grain were identified as the Fusarium graminearum teleomorph Gibberella zeae fruit bodies of ascospores producing perithecia. In our study, black dots were detected in 85% of the tested wheat grain samples collected from various commercial enterprises of Lithuania. The study showed the highest DON concentrations to be present in the samples with Fusarium-damaged grain exceeding 1%, while in the black-dotted grain samples DON concentrations were low. Grain samples for the storage experiment were selected according to the abundance of black-dotted and Fusarium-damaged grain with a moisture content ranging from 19.0% to 19.7%. Black dots on grain did not cause an increase in DON concentrations in grain samples, while the samples with more than 1% visually estimated Fusarium-damaged grain showed higher DON concentrations. The study findings suggest that grain damage by black dots, higher moisture content; storage temperatures (4, 16, 20 and 28 °C) had no significant effect on the increase in DON concentrations. However, it is risky to store grain of higher moisture when the amount of visually estimated Fusarium-damaged grain in the sample exceeds 1%. A significant increase in DON concentrations was recorded in such samples. Although DON concentrations in black-dotted grain samples were low, such grains are arguably a source of pathogens and need to be treated with a high degree of responsibility and thoughtfulness.

Keywords: black-dotted grain, Fusarium-damaged grain, deoxynivalenol, wheat grain.

Full text: 106_3_str32.pdf