EFFECT OF ULTRADRY ON SEED VIGOR AND SEED WATERTHERMODYNAMIC CHARACTERS
超干对种子活力及水分热力学特性的影响

Vigna Sesquipedalis seeds which were sensitive to ultradry and Brassica parachinensis seeds which were not sensitive to ultradry were used as experimental materials. Effect of ultradry on seed vigor, water sorption isotherms(WSI) and water thermodynamic parameters such as differential enthalpy(ΔS), differential entropy(ΔH),differential free energy(ΔG) were determined. Ultradrying treatments reduced V. Sesquipedalis seeds vigor and the activities of superoxide dismutase(SOD) and peroxidase(POD) and injured the cell membrane. Those harmful changes induced by ultradrying treatments occurred during ultradrying and subsequent storage under ultradry conditions. At the same time, ultradrying treatments did not induce any significant changes either seed vigor or the activities of SOD and POD of B. parachinensis seeds, and the slight damage of cell membrane induced by ultradrying treatments could be repaired during the seeds imbibition. After ultradrying treatments, the water contents of ultradried seeds in the WSI especially at the region 1 and region 2 were reduced. There were a slight increase of -ΔS and -ΔH at the region 1 of WSI, -ΔS,-ΔH at the region 2 and region 3 and -ΔG at the all regions of WSI were decreased to a various degree. In those changes the V. sesquipedalis seed is more significant. Those indicated that water binding ability of V. sesquipedalis seed was lower and it was easier to loss the essential binding water in the WSI, and then easier to induce structural changes of macromolecules. But for B. parachinensis seeds, the situation was the contrary, so it can keep the enzymatic activities and structure of cell membrane well, and was suitable for ultradry storage.