Alterações fisiológicas e oxidativas durante o armazenamento em sementes de Moringa oleifera Lam.

Abstract

Oxidative damage plays a central role in seed deterioration during storage. In this way, the present work aimed to characterize viability and vigor as well as oxidative damage and protection during the storage of Moringa oleifera Lam. (moringa) seeds. Seeds were kept in plastic bags and stored in a growth chamber (27 ± 2°C and RH 65%) or in a refrigerator (4 ± 2°C and RH 25%) for eighteen months. Samples were collected just after harvesting and every three months during storage, evaluating water content, germination percentage, germination speed index, percentage of abnormal seedlings, K+ leakage, H2O2 content, lipid peroxidation, protein carbonylation, reduced ascorbate content, as the activity of superoxide dismutase, ascorbate peroxidase, phenol peroxidase and catalase. A decrease in the percentage of abnormal seedlings occurred more sharply in the seeds stored in the growth chamber than in those stored under refrigeration for 18 months. Regardless of the storage environment, lipid peroxidation and protein carbonylation remained unchanged, whereas the content of H2O2 and POX activity decreased in parallel with an increase in the AsA content and SOD, APX and CAT activities. The viability and vigor of moringa seeds are best conserved under refrigeration and low RH for a maximum period of 15 months. Loss of quality after this time can not be associated with the accumulation of H2O2, lipid peroxidation and protein oxidation. Preservation of AsA levels and SOD, APX and CAT activities seems insufficient to maintain viability and vigor of moringa seeds after 15 months of storage.