The Laws Of The Seed Absorption And Desorption For Different Types And Physiological And Biochemical Variations In The Decreasing Process Of Vigor

In this study, silty type and protein type seeds with different initial moisture content (IMC) were used to study the laws of the seed moisture absorption or moisture desorption under different storage conditions (temperature and humidity), and the regression equation between equilibrium time and 3 factors(initial moisture content, storage temperature and relative humidity)was established and tested. Meanwhile, physiological and biochemical characteristics variations in the falling process of seed vigor under different storage conditions were studied, aiming to providing theoretical basis for seed storage safety. The main conclusions were as followings:1. The laws of seed moisture absorption or moisture desorption were different for seed types and storage conditions. The soybean seeds presented moisture desorption when the storage temperature (ST) was 15℃, 25℃, 40℃and the relative humidity (RH) was less than 18.78% (4% IMC) or 48.10% (8% IMC and 12% IMC), and presented moisture absorption in other storage conditions. The cotton seeds presented moisture desorption on condition that the ST=15℃and RH<7.49% (4% IMC), 18.78% (8% IMC) or 48.10%(12% IMC) depends on different IMC. The cotton seeds also presented moisture desorption when ST=25℃, RH<18.78% (4% IMC) or 48.10% (8% IMC and 12% IMC), or ST=40℃, RH<7.49% (4% IMC) or 48.10% (8% IMC and 12% IMC), and presented moisture absorption in other storage conditions. The maize seeds with 8% IMC under the condition of the storage temperature (ST) 15℃, RH<18.78% or ST=25, 40℃, RH<48.1% presented moisture desorption, so did the ones with 13.5% and 18% IMC under the condition of ST= 15, 25, 40℃and RH<48.1%, and presented moisture absorption in other storage conditions. The wheat seeds presented moisture desorption on condition that the ST=15, 25, 40℃and RH≤18.78% (8% IMC) or 48.10% (18% IMC) depends on different IMC; The ones with 13.5%IMC presented moisture desorption when ST=25℃, RH<18.78% or ST=25, 40℃, RH<18.78%, and presented moisture absorption in other storage conditions. 2. The predictive model of equilibrium time (d) depends on IMC (x), RH (y) and ST (z) were established and tested. The predictive model was d=36.97 +1.78 x-0.58 y-0.58 z-0.016 xy-0.021 xz-0.0012 yz+0.007 y2 for Fengkangmian 6, d=23.29+3.72 x-0.19 y-0.86 z-0.02 xy-0.09 xz-0.008 yz+0.005 y2+0.03 z2 for Liaodou 11, d=48.64+0.36 x-0.44 y-1.49 z-0.008 yz+0.006 y2+0.026 z2 for Hed- ou 13, d=35.34+4.32 x-0.28 y-0.35 z-0.031 xy-0.012 xz-0.0011 yz+0.003 y2 for Zhengdan 958, d=39.76+2.35 x-0.39 y-0.27 z-0.022 xy-0.014 xz-0.0057 yz+ 0.008 y2 for Nongda 108, d=25.69+7.65 x-0.27 y-0.89 z-0.12 xy-0.07 xz-0.007 yz+0.006 y2+0.04 z2 for Shannong 15, and d=46.67+0.39 x-0.28 y-1.72 z-0.006 yz+0.006 y2+0.017 z2 for Tainong 18. Through the model test, F<2.39, which indicated that conformity was high between the predictive value and the test value.3. Physiological and biochemical characteristics variations in the falling process of seed vigor. The higher the ST was, the worse the germination rate, germination energy, seedling height, seedling weight were with the prolongation of storage time at a given seed IMC, and so were the activities of POD and CAT; There were differences for physical and chemical index variations under different ST: The decreasing range for the activities of acid phosphatase and glutamate dehydrogenase were shown as high temperature> middle temperature> low temperature, and so were the increase range for the content of seed free proline, the conductivity of leaching solution and the content of MDA. The higher the seed IMC was, the worse the germination rate, germination energy, seedling height, seedling weight were, and so were the activities of POD, CAT, acid phosphatase and glutamate dehydrogenase, while the increase range for the content of seed free proline, the conductivity of leaching solution and the content of MDA showed opposite with the prolonga- tion of storage time at a given ST. The variations of all the vigor indexes in artificial aging test were the same as the above.4. There were different requirements for the 2 seed types in safe storage. According to the results of this study, the RH should be below 55% for wheat seeds in the safe storage, and should be below 60% for maize seeds; The ST for wheat and maize seeds in longterm safe storage should be below 15℃; The seed moisture should be below 12% in wheat seeds, and should be below 13% in maize seeds. The RH should be below 55% for cotton seeds in the safe storage, and should be below 60% for soybean seeds; The ST for cotton and soybean seeds in long-term safe storage should be below 15℃; The seed moisture should be below 9.5% in cotton seeds, and should be below 12% in soybean seeds.