homogeneity of seeds in size (primarily thickness). A batch of 1,000 seeds can have a high weight but consist of seeds of nonuniform sizes (large and small) that have varying sowing and harvest properties. It is necessary that the 1,000-seed batch have a high weight and that the seeds have good uniformity (not less than 80 percent for quality standardized seeds), since the uniform development of sprouts depends on these factors. Seed uniformity depends upon the methods of growing seed plants, meteorological factors, the structure of the inflorescence, and other factors. Even in well-developed plants there may be unevenness of seeds, caused by their position in the inflorescence. Thus, in cereals the kernels in the central part of the ear are larger and heavier than those in the upper and lower parts. Seed uniformity is particularly important in cluster and single-spot sowing, and therefore corn and other crops are graded by size. Cleaning and sorting seeds also helps achieve uniformity. Seed uniformity is ensured by state seed inspection.
The seeds are divided into groups according to size, weight, and aerodynamic properties, and the sum of the two largest adjacent groups is expressed as a percentage of the initial weight.
M. K. FIRSOVA