Maize (Zea mays L.) yield and aflatoxin accumulation responses to exogenous glycinebetaine application

Exogenously applied glycinebetaine (GB) accumulates at high levels in maize (Zea mays L.). Under water deficit and high temperature conditions GB application produces yield benefits. These sub-optimum conditions often result in high levels of aflatoxin accumulation which reduces grain quality. A 3-year (2008, 2009 and 2010) field experiment was conducted to determine the effects of GB on maize yield and aflatoxin accumulation. Weekly and alternate weekly GB application increased plant biomass by 10 and 13%, respectively. Net photosynthesis increased by 6% with GB application; however, stomatal conductance, transpiration rate and electron transport rate were not significantly affected. Grain yield increased by 6 and 13% with GB applied alternate weekly and weekly, respectively, over control plots averaged over years. GB application resulted in a trend of reduced aflatoxin accumulation in inoculated ears compared with non-inoculated controls in 2009 and 2010; however, inherent field and sampling variation did not allow us to conclude statistically any advantage attributable to GB application. We can conclude that GB did not significantly reduce aflatoxin production in the inoculated treatments.