Physiological Basis for Inhibition of Maize Seed Germination by Flooding

Field emergence of maize (Zea mays L.) can be severely reduced by flooding shortly after planting. This study was conducted to characterize the response of several maize inbreds to soaking injury and to examine the importance of ethanol and acetaldehyde accomulation as determinants of tlooding tolerance. Seeds of four maize inbreds (Z38, B49, G49, and GS0) were soaked from 0 to 7 d 27 °C. Subsequent germination of Z38 and IM9 was relatively unaffected by this treatment, while germination of G49 and GS0 was reduced to <10%. Soak temperature affected germination, with minimal inhibition at 15 to 20 °C and maximal effects at 0.1 and 40 °C. All inbreds excreted ethanol and acetaldehyde during soaking, but amounts excreted were not significantly correlated with subsequent germination. Purging the soak water with air or N2 gas during soaking resulted in subsequent improvements in germination. Soak‐induced inhibition of germination was partially reversed by venting the seed after soaking but prior to planting. Venting was accomplished with flowing air, N2 gas, or a vacemn treatment. Treatment with ≈0.15 MPa (1.5 atm) of total pressure resulted in no improvement in germination after soaking. These data are consistent with the concept that soak‐induced inhibition of germination results from accumulation of volatile metabolite(s) other than ethanol or acetaldehyde.