Effects Of Storage Years On Seed Physiological And Biochemical Characteristics Of Oat

In order to study the effects of storage years on the physiological and biochemical characteristics of oat seeds,four oat varieties(Baiyan No.2,Dingyou No.6,Longyan No.2,Baiyan No.7)were used as materials,the germination characteristics,seedling growth,osmotic adjustment,enzyme activity and malondialdehyde content of oat seeds were studied with different storage years.The main results were as follows.(1)The moisture content of tested oat seeds was between 6.12% and 8.05%,which was significantly lower than the safe moisture content and less affected by the storage years.The oat seed germination potential,germination rate,germination index,vigor index,seedling shoot length and root length decreased with the prolongation of storage years,while the conductivity of seed extract increased remarkably and membrane permeability increased accordingly.During the 1~4 year storage period,Baiyan No.2,Dingyou No.6 and Baiyan No.7 seeds all had germination rate of over 88%.When Longyan No.2 was stored for 2 years,the germination rate decreased from 94.67% in the harvest year to 84.33%,and further decreased to 73.00% in storage for 4 years.Baiyan No.2,Dingyou No.6 and Baiyan No.7 should not be used for seed after 4 years of storage,and Longyan No.2 lost its seed value after 1 year of storage.(2)Storage years had significant effects on oat seed osmotic adjustment substances and storage substance.The soluble sugar content increased during the storage period of 1~4 year,and then the soluble sugar contents of Baiyan No.2 and Dingyou No.6 decreased significantly,while Longyan No.2 and Baiyan No.7 continued to rise.The soluble protein content of oat seeds increased first and then decreased with the increase of storage years.The soluble protein content of Baiyan No.2,Dingyou No.6 and Baiyan No.7 reached the maximum at 1 year of storage and then decreased gradually.When stored for 8 years,it decreased by 13.44%~38.56% compared with 1 year.The proline content had similar variation tendency with soluble protein.Baiyan No.2 and Dingyou No.6 reached a peak stored for 2 years,and Longyan No.2 and Baiyan No.7 reached a peak stored for 4 years,and then all decreased significantly.The starch content showed a general downward trend.Baiyan No.2 had the largest decline,and storage for 8 years decreased by 19.13% compared with the harvest year.(3)The germination potential and germination rate of oat seeds was significantly positively correlated with the activities of antioxidant enzymes(SOD,CAT,POD).During the storage period of 4 years,the activity of antioxidant enzymes of Baiyan No.7 seed increased,and then decreased sharply.At 8 years of storage,activity of SOD,CAT and POD decreased by 84.96%,11.28% and 84.54% compared with 4 years of storage respectively.The other three varieties also had large declines with the prolongation of storage years.Dehydrogenase and protease activity of oat seeds increased first and then decreased with the prolongation of storage years.The activity of polyphenol oxidase increased with the prolongation of storage years,but the variation among varieties was significant.The content of malondialdehyde increasedwith the increase of storage years.The antioxidant enzymes and ?-amylase activity of oat seed were significantly positively correlated with germination potential and germination rate,and could be used as the main physiological indicators for seed vigor determination.In summary,storage time was the most important reason for the changes in oat seed vigor,osmotic adjustment substances,storage substances,and enzyme activities.Among the four tested oat varieties,Baiyan No.7 had the best storage resistance.