Short-Term Liquid Nitrogen Storage of Maize, Common Bean and Soybean Seeds Modifies Their Biochemical Composition

We studied the effects of liquid nitrogen storage of maize, common bean and soybean seeds on their germination, electrolyte leakage, levels of chlorophylls, phenolics, aldehydes, proteins and peroxidase activity. After storage for 28 days, seeds were retrieved from liquid nitrogen, some were set to germinate and others were analyzed biochemically. No phenotypic modifications were observed visually 5 days after beginning of germination, although percentage of seed germination was reduced by LN in maize and soybean. Moreover, numerous significant effects of seed cryopreservation were recorded at the biochemical status. In maize seeds, the most important and statistically significant modifications were observed in the increased levels of chlorophyll b and total chlorophyll pigments and in the decreased contents of free phenolics after 28 days of exposure to LN, compared to the control treatment. In common bean, relevant changes were observed in the increased electrolyte leakage and in the reduced levels of chlorophyll pigments (b, total) and free phenolics. In soybean, modifications were observed in the increased levels of chlorophyll pigments (a, b, total), malondialdehyde and electrolyte leakage, and in the decreased peroxidase activity. We have shown for the first time that immersion of maize, common bean and soybean seeds in liquid nitrogen modified the levels of different biochemicals.