Abstract:

【Objective】The present study aimed to determine the effects of dehydration on the physiological responses of Phoebe zhennan seeds, to provide a basis for a long-term seed preservation. 【Method】Phoebe zhennan seeds were dehydrated using the silica gel. When the water loss reached 0, 3%, 6%, 9%, 12%, 15% and 18%, physiological indexes of the samples were measured. 【Result】The initial water content of P. zhennan seeds was 37.74%, viability was 89.41%, and the half-lethal water content was 29.09%. The viability of P. zhennan seeds gradually decreased during the gel dehydration, and the electrical conductivity and malondialdehyde (MDA) contents continuously increased. Superoxide dismutase (SOD) and catalase (CAT) activities first increased, then sharply decreased. The activities of SOD and CAT negatively correlated with electrical conductivity and MDA content (correlation coefficients: -0.833 and -0.743; -0.819 and -0.871, respectively). The results showed that dehydration inhibited the viability of the protective enzyme system, and strengthened membrane lipid peroxidation. The decrease or complete loss of seed viability led to the increased membrane permeability and peroxide accumulation. 【Conclusion】Water conditions should be carefully managed during storage because P. zhennan seeds are highly recalcitrant. However, slight dehydration can stimulate activity of the protective enzyme (antioxidant) system, which helps to improve the dehydration tolerance. The optimum water content for P. zhennan seeds’ preservation is 34.74%, and in actual production, it can be controlled within its 3%.

Key words: recalcitrant seed, dehydration tolerance, antioxidant enzyme, membrane lipid peroxidation, seed storage