Usefulness of 13 morphological and phenological characteristics of sweet chestnut (Castanea sativa Mill.) for use in the DUS test

Abstract

The descriptive value of 13 chestnut characteristics was assessed in the present study. The variables were measured over a period of 3 years in a contemporary collection of traditional cultivars located in two different environments in the northwest of the Iberian Peninsula. Descriptors, which are particular to each species, are used in the characterization, differentiation and protection of cultivars and should comply with the following three criteria: distinctness, uniformity and stability (DUS). Evaluation of the morphological and phenological characters was carried out with some UPOV descriptors and other descriptors previously recommended on the basis of their potential usefulness for the DUS test. ANOVA models were used to estimate the genetic and environmental components of variability and the genotype × environment interaction, with the aim of determining the properties of different descriptors for use in the DUS test. Most of the variables differed significantly among the cultivars, with high to very high heritabilities of between 0.63 and 0.97. Exceptions were observed with the variables fruit size, chestnut length and time of fruit ripening, which did not differ among cultivars in either plantation. The variables that showed the highest degree of distinctness, uniformity and stability were: time of leaf bud burst, filament length in male flower, time of beginning of male and female flowering, size of fruit hilum, and percentage of chestnuts with split pericarp. In contrast, time of fruit ripening, fruit size and chestnut length showed a low degree or no distinctness and highly heterogeneous degrees of uniformity and stability.