Biological and pomological characteristics of superior walnut selections

Abstract
As late spring frosts are a limiting factor to successful growth of walnuts attention was focused on walnut selection in years when late spring frosts occur after bud swelling. This particularly referred to the years of 1998 and 2002, and, partly 2001. In those years, 32 walnut trees were found to produce satisfactory yield in regions severely affected by string spring frosts and were subjected to careful observation in the following years. Of that number, 11 trees were found exceptional. They were characterized by luxuriance, vigour, satisfactory resistance to walnut antracnose, and yielding capacity. Fruits had good quality and favorable characteristics of the shell (smooth, thin, light-colored, easily separable) and kernel (relatively smooth, light-colored, tasty). Fruit mass measured 18.0-9.3 g kernel mass 8.6-4.1 g, and kernel content 55.0-47.0%. The kernel contained 67.0-61.1% oil, 19.3-14.5% crude proteins and 2.65-2.12% mineral matter. All investigated selections had been grafted. They were grown in identical conditions, in collection, and the ones found best for commercial growth were selected.