Effects of plant growth regulator applications on malting barley in western Canada
Tidemann, B.D., O’donovan, J.T., Izydorczyk, M., Turkington, T.K., Oatway, L., Beres, B., Mohr, R., May, W.E., Harker, K.N., Johnson, E.N., de Gooijer, H. (2020). Effects of plant growth regulator applications on malting barley in western Canada. Canadian Journal of Plant Science, [online] 100(6), 653-665. http://dx.doi.org/10.1139/cjps-2019-0200
Plain language summary
Malting barley is an important economic crop in western Canada, yet many of the acres seeded to malting cultivars do not make malt quality, in part due to factors like lodging. Lodging, when the plant falls over from the stem or the root, can decrease barley yield and quality thus reducing the probability of acceptability for malting. In other countries chemicals with plant growth regulator (PGR) properties are commonly applied to prevent and manage plant lodging. Chlormequat chloride, trinexapac-ethyl and ethephon, plant growth regulating chemicals, were tested at five locations over 3 years in western Canada for their ability to limit lodging, as well as their effects on other pre-malt quality characteristics. Chlormequat and trinexapac are applied at a similar time, while ethephon is applied when plants are bigger. In this study some of the applications occurred at a later than desirable stage, particularly for ethephon. Seeding rates of 200, 300 and 400 seeds per square meter of CDC Copeland barley were also used. Seeding rate didn't interact with the PGR treatments. Ethephon reduced plant height but increased tillering (branching) of the plant, while reducing kernel quality. It also increased the number of days needed for the barley to mature. Trinexapac decreased plant height and kernel weight. Trinexapac was the most likely of the PGRs to reduce lodging. It is not registered on barley and weather still impacted the likelihood of barley lodging, even when PGRs were applied.
Malting barley is important in western Canada, yet many malting cultivars do not meet malt quality standards, in part due to lodging. Lodging can decrease barley yield and quality thereby reducing the acceptability for malting. In other countries, plant growth regulator (PGR) applications are used to mitigate lodging. Chlormequat chloride (chlormequat), trinexapac-ethyl (trinexapac), and ethephon were tested at five locations over 3 yr in western Canada for their ability to limit lodging, as well as their effects on yield, agronomic traits, and pre-malt quality characteristics. PGR applications occurred between Zadoks growth stage (GS) 30–33 for chlormequat and trinexapac and GS 37–49 for ethephon. Seeding rates of 200, 300, and 400 seeds m−2 of CDC Copeland barley were used to increase the likelihood of lodging. Increased seeding rate decreased tillers per plant, height, days to maturity, kernel protein, and kernel weight. Ethephon increased the number of tillers per plant and decreased plant height, kernel plumpness, and kernel weight. Trinexapac decreased plant height and kernel weight. Days to maturity was investigated across site-years, with ethephon increasing maturity in 60% of comparisons. Trinexapac and chlormequat had limited effects on maturity. Lodging was investigated across site-years, with trinexapac showing the largest number of lodging reductions and scale of reductions. Ethephon reduced lodging in 36% of comparisons, while chlormequat had inconsistent effects. None of the products affected yield or grain protein. The results suggest PGRs may not be the solution to lodging for CDC Copeland barley on the Canadian Prairies; however, trinexapac shows the most promise of the products tested.