Physical properties of horticultural products are important in designing the sorting, transporting, processing and packaging systems. Among physical attributes, dimensions, weight, volume, projected areas and porosity are useful for designing grading systems. This study carried out on four superior walnut (Juglands regia) genotypes, which were selected from primary morphological screening of 608 genotypes in Neyriz city, Iran. G-570 with higher nut weight (12.46 g), kernel weight (8.25 g) and kernel ratio of 66.21% was a promising genotype among others. Regarding studied physical properties, G-570 was 44 mm in diameter significantly different from other genotype. In this research walnut mass was predicted by using different physical properties with linear and nonlinear models as three classifications (dimension, projected areas and volume). Results showed that the highest correlation was between models number three, two and one. Among grading system based on dimensions in walnut (first classification), minor diameter model with nonlinear relation was the best and could be considered as a good model for economical and horticultural designing systems. (c) 2009 Published by Elsevier B.V.
