Fruit Quality Properties of Walnut (Juglans regia L.) Genetic Resources in Montenegro

Abstract

Centuries-old generative reproduction, relatively favourable agro-ecological conditions, natural selection, and anthropogenic roles have significantly influenced the formation of a rich, heterogeneous population of common walnuts in Montenegro. This variability can be exploited by applying a positive selection of genotypes that would have good ecological adaptability and high economic value and that would not lag behind walnut varieties originating from other countries. The paper presents the results of studying 20 selected walnut genotypes from the continental part of Montenegro in a three-year period. Šeinovo variety and the Rasna selection were used as standard. The most important biological and pomological properties were investigated based on the international walnut descriptor. The basic criteria on which the selection approach was based were: late vegetation initiation, earlier date of end of vegetation, well kernel ratio, ease of kernel removal from the shell, shell texture that should be less rough, protecting the kernel, tasty kernel, light coloured kernel, and good chemical composition of the kernel. Genotypes had fruit weight between 8.43 and 13.84 g, kernel weight between 4.20 and 6.54 g, kernel ratio between 39.20 and 52.25%, oil content between 62.04 and 67.23%, and protein content between 13.91 and 19.04%. Most of the selected genotypes have the late time of leaf bud burst, and from that point of view, the BP44 and BP42 genotypes that the leafing on May 5 and 6 are especially interesting, due to avoidance of late frost. The walnut is adapted to the existing agro-ecological conditions over a long period of successful growth in this region, and most genotypes finish their vegetation earlier and are prepared to enter the period of winter dormancy. Genotypes BP09 and AN29 with their properties surpass the worldwide recognized Šeinovo, and in this region, highly valued selection Rasna. BP48 and BP50 genotypes also deserve attention due to the quality of the fruit.