Determination of safe storage moisture content of commercial maize (Zea mays) seeds during hermetic storage: Presentation

Abstract

Germination declines during storage and meeting official standards (90% limit) can be challenging for the seed industry. Hermetic storage, through the establishment of self-modified atmospheres has shown to preserve germination in high-moisture maize seeds, but in the range of the low-moisture contents (m.c.) used by the seed industry, the relationship between hermetic storage and seed quality has not been fully studied. The aim of this work was to determine the safe storage m.c. of commercial maize seeds during hermetic storage considering both germination and microbiological aspects. Maize seeds with 95% initial germination were conditioned to m.c.s. between 11.5 and 14.5% and stored hermetically at 25oC for 6 months. Germination, % oxygen, % infected grains, and colony forming units (CFU) were evaluated. Germination declined with increasing m.c.s, dropping to 50% at 14.5% m.c. Microflora respiration started to be detected at 13.5% m.c. and an anaerobic self-modified atmosphere was reached at 14.5% m.c. Despite the higher relative humidity, % infected grains and CFU count at 14.5% m.c. were lower than at 13.5%, probably due to the suppressive effect of the anaerobic atmosphere. In conclusion, 11.5% was a safe storage m.c. as it preserved germination above marketing requirements without microbiological risk. Hermetic storage was useful to generate self-modified atmospheres for m.c.s above 13.5%, but these self-modified atmospheres were not effective to protect germination. Further research on the effects of controlled and self-modified atmospheres on the quality of different maize genotypes is needed to evaluate the benefit of hermetic storage of commercial seeds.