Optimal spatial and temporal measurement repetition for reducing environmental variation of berry traits in grape breeding

Environmental variance components were estimated for berry ripening time (BRT), berry weight (BW), soluble solids concentration (SSC), titratable acidity (TA), and deformation at the ®rst major peak (DFP) and maximum force (MF) in penetration tests of berry ̄esh in grapes (Vitis vinifera L. and V. labruscana Bailey). The variance among berries within clusters was largest among environmental variance components for BW, SSC, DFP and MF. The variance among clusters within vines was smaller than the variance among berries within clusters for all traits. The sum of the variance among years and the variance associated with the genotype year interaction was generally larger than that among vines within genotypes. Consequently, increasing the number of yearly repetitions was more ef®cient than increasing vine replications in evaluating the genetic potential in breeding. # 2000 Elsevier Science B.V. All rights reserved.