Correlations between basic physical parameters of nuts and the weight of common beech (Fagus sylvatica L.) seeds

Selected physical attributes of common beech nuts harvested from four tree stands in northern Poland were determined. Seeds were manually extracted from every nut. Seeds and nuts were weighed, and the results were used to determine the ratio of seed weight to nut weight, which described the degree of nut filling. Physical parameters and the calculated coefficients were compared by the t-test for independent samples, analysis of variance, correlation analysis and linear regression analysis. The following ranges of variation were reported in the physical attributes of nuts and the coefficients of common beech seeds: critical transport velocity of nuts - from 6.33 to 11.28 m s-1, nut thickness - from 4.76 to 9.86 mm, nut width - from 6.46 to 13.54 mm, nut length - from 12.63 to 21.62 mm, angle of sliding friction of nuts - from 15.67 to 26.67o, nut weight - from 93.0 to 513.7 mg, coefficient of sliding friction of nuts - from 0.28 to 0.50, seed weight - from 11.0 to 374.8 mg, and ratio of seed weight to nut weight - from 0.08 to 0.88. The majority of nuts contained one seed (average weight of 195.36 mg), and only 2.3% of nuts contained two seeds (average weight of 103.11 mg). The attribute that was most highly correlated with the ratio of seed weight to nut weight was seed weight (0.685), followed by critical transport velocity (0.527) and weight of nuts (0.493). The results indicate that common beech seeds would be processed most effectively in vibration-pneumatic separators or, alternatively, in pneumatic separators where nut fractions obtained with the use of mesh screens can be sorted separately.