Abstract:

Watermelon（Citrullus vulgaris Schrad.）seeds of two diploid varieties，Wanza 1 and Fengshou 2，were pre-dried at different levels of silica gel and then stored for 23 years under room temperature and hermetic conditions. The best storage treatments had 96% and 91% germination percentage for Wanza 1 and Fengshou 2 varieties when the seed water content was adjusted at 2.32% and 2.23% respectively. The germination-ability of the seed was negatively correlated with the seed water content during storage period. Positive correlations were found between both POD activity and sucrose content with the germination percentage，but SOD activity showed a negative correlation with the germination percentage. In addition，the viability of Wanza 1 of each treatment were compared after 9，15，20 and 23 years of storage. For the seed with water content of 5.22% or higher，the germination percentage declined quickly. However，seed water content with range of 1.65% and 4.12%，the germination percentage were well retained after 20–23 years of storage. These results suggest that diploid watermelon seeds can retain high viability under ultra-dry condition in the long term storage.

Key words: watermelon, seed, ultra-dry storage, germination percentage, antioxidant enzyme, sucrose, storability