Spatial variation is known to affect cereal growth and yield but consequences for seed quality are less well-known. Intra-field spatial variation occurs in soil and environmental variables and these are expected to affect the crop. The objective of this paper was to identify the spatial variation in barley seed quality and to investigate its association with environmental factors and the spatial scale over which this correlation occurs.

Two uniformly-managed, commercial fields of winter barley (cv Cassia, 4 ha, 2013; cv. California, 9 ha, 2014) in south east England, were assessed for spatial variation in germination, vigor, thousand grain weight and seed moisture content. Variable features within the fields included soil type (gravel terraces, clay cap and moisture retentive gullies) as well as an undulating topography. Unbalanced nested sampling design were designed based for each field based on pre-existing spatial data. The unbalanced sampling design included five spatial scales (1-81 m) with 138-150 sampling points per field. Canopy variables and soil samples were assessed at each point. Seed quality variables varied more over long (i.e. > 20 m) than over short (i.e. < 20 m) distances. Although germination and vigor tests were correlated at a 2.7m spatial scale with some canopy and soil variables, variation over this distance is not manageable by the farmer although it may assist in understanding intra-field variations.  Correlations of seed quality with canopy and environmental variables also tended to be stronger over the longer distances. Some seed quality characteristics such as seed moisture content at final harvest, varied over long distances (>60 m). In terms of precision management of the field, seed producers might be able to harvest and dry seeds separately from different parts of the field. Site-specific management in the field can therefore be proposed depending on the spatial variability of seed quality variables.