| Wheat Fanmai No.8,Fanmai No.803,Zixuan No.39 and old varieties of wheat Abbondanza,Lovrin No.10,and Huixianhong were used in this experiment.The large and small seeds were screened out as the test materials by slotted screens of 3.0×20mm,2.5×20mm and 2.3×20mm.Field investigation of the agronomy characters of the wheat were conducted at different growth stages,lodging resistance was measured at maturity,and the yield and yield traits were investigated after the seeds were harvested.The seed germination experiment and the measurement of seedling root vigor and morphology were conducted in laboratory.The results were as follows:(1)The seed size has no significant effect on germination percentage.The small seeds germinate faster than the large ones,while the vigor indexes of the large seeds were higher than that of the small ones.The results of the field seedling emergence showed that the the percentage of the seedling emergence of the large seeds was slightly higher than that of the small ones without significant difference.Therefore,it is thought that the germination of large seeds is later than those of small grains,but the seedlings of large seeds grow faster than that of small ones in the late stage of seedling growth.(2)The seedling root activity of unit mass gradually decline with the seedlings growing for both of them,and the seedling root activity of the large seeds has been higher than that of small grains.On seedling root morphology,differences between large and small grains were not obvious at the beginning of the germination,with the growth of seedlings,the length,volume and surface area of the roots increased,the difference between grain sizes is gradually obvious,the seedlings of the large grains grew faster than that of small grains.While the average root diameter decreased with the seedling growing,no obvious difference between the seeds of two sizes.The results showed that there were significant differences in root length,root volume and root surface area,and there was no significant difference in the mean root diameter.(3)With the plant growing,the difference in the seedling stage was gradually narrowed after the overwintering period and the reviving period.The investigation on plant height at the filling period suggested that no evident differences between the plant height of seed of the two sizes.The stalk resistance test found no evident differences exist between the plant lodging-resistance capability of the large seeds and small ones of one variety.Among different varieties,the old varieties were highly susceptible to lodging due to the high plant height and thin stalks,while the new breeds perform well and the lodging is very light.(4)The output comparison at the mature stage suggested that there is no significant difference between the large seeds and the small ones considering the TKW(thousand kernel weight),the number of the ears per mu,and the numbers of the kernels on each ear.The output of the large seeds is slightly higher than that of the small ones.The large seeds of the varieties Zixuan No.39 and Fanmai 8 yield significantly higher than the small grains,while the output of the large seeds of the variety Lovrin No.10 is significantly below that of the small ones.The large grains yield of Fanmai No.803,Abbondanza and Huixianhong was higher than that of small grains,but the difference was not significant.The seeds produced by different sizes of grains of different varieties had no significant difference in grain shape,except for Fanmai No.8 with larger seeds produced by large grains.(5)It is suggested to classify seeds in those variaties of which either the large or the small seeds have obvious advantages so as to avoid the resource competition of seedlings when the seeds are mixed to sow.At the same time,the field management of small seed seedlings should be strengthened to enable the strong seedlings form as early as possible to ensure higher yield. |
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