Effects of plant growth regulator application on the malting quality of barley

Citation

McMillan, T., Tidemann, B.D., OʼDonovan, J.T., Izydorczyk, M.S. (2020). Effects of plant growth regulator application on the malting quality of barley. Journal of the Science of Food and Agriculture, [online] 100(5), 2082-2089. http://dx.doi.org/10.1002/jsfa.10231

Plain language summary

Plant lodging, where the plant bends or breaks at the stem or at the root level and leans over, can negatively affect the yield of barley, as well as the quality of the barley grain. Plant growth regulators (PGRs), chemicals that affect how the plants grow, are used globally to reduce barley height and therefore reduce the risk of lodging. PGR's produce shorter, thicker and stronger stems. However, it is possible that applying PGRs could also affect the characteristics of barley that are important for malting performance and the production of malt. This study examined the effect of applying 3 PGRS (ethephon, chlormequat, and trinexapac) to malting barley in several locations and years in western Canada. In addition, multiple seeding rates were used to try to increase the likelihood of lodging, which is difficult to predict and often dependent on weather conditions. However, if lodging doesn't occur it's difficult to determine if PGRs were helpful in preventing lodging. The results of the study showed that PGR treated barley had a lower weight to it's kernels, compared to barley that was not treated with PGRs. PGRs had no effect on protein concentration or germination energy, both important qualities to malt performance. Seeding rates had significant effects on barley kernel weight, protein content and germination index, but did not interact with PGRs for any effects on barley. Although PGR treated barley had smaller kernels, this did not affect many of the characteristics investigated in terms of malt performance. Overall there was slightly less fine extract produced for PGR treated barley, compared to untreated barley, however this was only statistically significant for chlormequat and trinexapac. The study concluded that although PGRs affected kernel plumpness and kernel weight, the effects of PGR application on the malting quality were generally quite small and insignificant. Few negative effects means that PGR application should not be restricted on malt barley because of concerns about malting quality.

Abstract

BACKGROUND: Lodging can negatively affect yield and quality of barley grain. Synthetic plant growth regulators (PGRs) reduce lodging by producing shorter, thicker, and stronger stems. However, the impact of applying PGRs on malting performance of barley is not known. The objective of this work was to assess the effect of application of three PGRs (ethephon, chlormequat chloride, and trinexapac-ethyl) in combination with different seeding rates on the malting quality of barley grown in several locations and years in western Canada. RESULTS: The kernel weight in PGR-treated barley was reduced by 1.7% to 6.5% compared with the nontreated grain. Application of PGRs had no effect on the concentration of proteins and germination energy. Seeding rates significantly affected kernel weight, protein content, and germination index (GI), but no interactions between PGRs and seeding rates were observed. The smaller kernels of ethephon‑ and trinexapac-treated barley showed good hydration and grain modification during malting, as indicated by high levels of starch-converting enzymes, high Kolbach indices, and low levels of wort β-glucans. Overall, the fine extract of malt from PGR-treated barley was slightly lower than that of the control malt; however, the extract reduction was statistically significant only for chlormequat‑ and trinexapac-treated barley. CONCLUSIONS: The application of PGRs had significant effects on kernel plumpness and kernel weight, but the effects of PGR application on the malting quality were generally small and insignificant. The decision of PGRs application on malting barley needs to be considered in combination with potential benefits of PGRs in mitigating lodging and their effects on the agronomic performance of barley. © Her Majesty the Queen in Right of Canada 2019.

Publication date

2020-03-30

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