Abstract

Seed germination is a vital stage in the morphogenesis of spermatophyte. Seed germination is regulated by storage substances and temperature. Melon is an important economic crop, and often encounters sub-low temperature environment at the seed germination stage in winter-spring, which limits the normal germination of melon seeds and affects melon production. Therefore, it is of great significance to explore the physiological mechanism of seed germination at low temperature. Here, two melon varieties, IVF521 (cold sensitive) and THY (cold tolerant), were used to study the germination and relative sugar metabolism at normal (28 °C) and low temperatures (15 °C). Results showed that THY seeds exhibited a higher cold tolerance but contained lower starch and soluble sugar than IVF521 seeds. Under normal conditions, IVF521 seeds germinated quickly and manifested a high germination percentage. Under low-temperature conditions, the neutral invertase of THY seeds were less inhibited by low temperature, which contributed to the sustained decomposition of Suc into glucose (Glu), providing energy substrate for seed germination. In addition, soaking with exogenous Glu can improve the germination rate of melon seeds at low temperature. Overall, Sucrose catabolism may play key roles in melon seed germination under low temperature.