Manganese application increases winter hardiness in barley

Manganese (Mn) deficiency is commonly connected with soil properties, and application of Mn is frequently performed to winter barley (Hordeum vulgare L) in fields with a history of deficiency. Since the availability of Mn also is affected by seasonal variations, there is a risk of excessive application in some seasons while the application is not sufficient in other seasons in such fields. The objective of this study was to investigate the effect of foliar application of Mn in autumn and early spring on barley winter hardiness, in combination with or without N application in autumn. We also evaluated a commercially available Mn-scanner as a tool to identify the need for Mn application. Two field experiments per growing season were performed in south Sweden in 2010-2011 and 2011-2012 in fields where Mn deficiency often occurs. Foliar applications of various Mn products were made once (in October) or twice (in October and in March the following year). A single dose of 0 or 30 kg ha(-1) N was applied, as N-NO3, in October. Barley leaves were collected and Mn status determined with the NN-Easy55 Mn-scanner. Yield was determined in the field experiments in 2011-2012. Our results showed that the requirement of Mn application varied between sites and seasons and was affected by N supply. Mn application increased the winter survival by 33% and the grain yield by 36% in the barley plants with the lowest Mn status in autumn. The risk of Mn deficiency increased when N (NO3-N) was applied in autumn. In one of the harvested field experiments, yield was suppressed by N application in autumn and was recovered by Mn application. Repeated Mn applications might be required to increase winter survival and grain yield, especially when N has been applied in the autumn. To reach an optimal Mn application, tools such as the NN-Easy55 Mn-scanner can be used to monitor the Mn status of the plants. Thereby unnecessary application of Mn is prevented and sufficient amounts are applied during deficiency. (C) 2014 Elsevier B.V. All rights reserved.