Study On The Seed Vigor Of Toona Sinensis Seeds Under Specific Storage Conditions

Toona sinensis(syn.Cedrela sinensis)is a perennial tree which belonging to the genus Polygonaceae.It is a rare species of fast-growing wood in China.In the production,the seeds of Toona sinensis need to be stored for about three months in winter,and the main producing areas of Toona sinensis are lack of low temperature seed bank.The environment of high temperature and high humidity is not good for storage.Therefore,the experimental simulation of south environmental conditions to explore the safe storage conditions of Toona sinensis.This article studied the changes of seed vigor during storage under different storage conditions,then revealed the relationship between seed vigor and storage conditions,and determined the safe storage conditions of Toona sinensis seeds,so as to provide the technical basis for the safe storage of Toona sinensis.According to the conditions of temperature and humidity in winter in parts of southern China,the storage conditions were set up as 9.1%,12.2%,14%,15.8%,17.8% moisture content and 10 centigrade,15 centigrade and 20 centigrade combined storage.Then the experiment studied the changes of germination rate,vigor index,electrical conductivity,MDA content and the activity of SOD,CAT and POD under different storage conditions in different storage period,and through the analysis of variance and linear regression of the experimental data of Toona sinensis seeds during storage of seed vigor,internal physiological and biochemical changes were analyzed and summarized.The results are as follows :1.The germination rate and vigor index of Toona sinensis seeds under different storage conditions decreased with the increase of storage time.After storage of 90 d,the seeds vigor with 9.1% mositure content kept at a high level at 10 centigrade and 15 centigrade,and the seed of Toona sinensis had lost the ability to germinate at 15.8% and 17.8% under the condition of 20 centigrade.2.Under the same storage conditions,the activity of SOD,CAT and POD decreased gradually with the increase of storage time,and the conductivity and MDA content increased gradually.Under the same water content and temperature,the rate of physiological and biochemical changes increased with the increase of temperature.With the same storage temperature and different mositure content,the electrical conductivity and MDA content increased gradually with the storage time.The membrane permeability related indicators of seeds with 9.1% mositure content increased slowly.The activity of SOD,CAT and POD decreased gradually,and the antioxidant enzyme activity of seeds with 9.1% mositure content decreased most slowly.Membrane peroxidation is one of the important reasons for the decline of Toona sinensis seed vigor.3.The effects of storage conditions on seed germination and physiological and biochemical indexes of Toona sinensis after storage for 90 days were significantly different(P < 0.01),and their interaction also reached a very significant level,which aggravated the rate of seed vigor decline.4.There was a significant positive correlation between the germination rate and activity index of seed and the activity of antioxidant enzymes.There was a negative correlation with the electrical conductivity and MDA content.SOD,CAT,POD,electrical conductivity and MDA content could effectively reflect the vigor of Toona sinensis seeds.5.Under the conditions of this test,the safe storage conditions of Toona sinensis seeds are as follows: when the temperature is not more than 15 centigrade,the moisture content should be controlled not higher than 12.2%,and the moisture content should be not higher than 9.1% when the temperature is between 15 centigrade and 20 centigrade.