132 Journal of Food, Agriculture & Environment, Vol.6 (3&4), July-October 2008 Evaluation of an isolated Persian walnut (Juglans regia L.) population from Eastern Transylvania, Romania Rezső Thiesz 1 , Attila Bandi 1 , Magdolna Tóth 2 and Adalbert Balog 1* 1 Department of Horticulture, Faculty of Technical Science, Sapientia University Tîrgu-Mureş, Ro-540485, POB 9, Cp.4, Tg- Mures/Corunca, Sighisoara str. 1C. Romania. * e-mail: balogadalbert2002@yahoo.co.uk., thiesz@ms.sapientia.ro, bandiattila@yahoo.com. 2 Department of Pomology, Faculty of Horticultural Science, Corvinus University of Budapest, 1118 Budapest, Villányi str. 29–43, Hungary. e-mail: magdolna.toth@uni-corvinus.hu Received 8 January 2008, accepted 25 March 2008. Abstract An isolated walnut population was investigated in Eastern Transylvania, Romania, in order to collect information for improving the present assortment of scion cultivars for the National and International Breeding Program. A total of 147 walnut individuals were investigated to determine 1) the main biological characteristics of the trees; and 2) to ascertain the main physical and qualitative characteristics of the nuts. The walnut population we studied can be considered as a genetically valuable one. Of the individuals 11% flowered between 29 th of April and 10 th of May, thus avoiding late spring frost damage. Such types bear abundantly in cold climate on lateral shoots and also have high quality fruit. In the present evaluation, 89% of the individuals had a mean flowering time between 18 th and 28 th of April. Although injuries from late spring frost are frequent in this area; the spring frost damage was low, and high quality fruit was obtained. Among the 147 individuals, 10 provided the best proportion of kernel mass compared with endocarp. Sensory characteristics of the nuts (size, colour, strength and flavour) were tested. The most valuable individuals, which were considered as prospective elites, were tested and compared with internationally recognised cultivars (‘Franquette’, ‘Hartley’, ‘Milotai 10’ and ‘Alsószentiváni 117’). Comparing the total quality scores of the 14 elites and cultivars in the study, we can observe that only one had a low score (Ozsd-37); however, its strength and flavour were similar to other cultivars. According to our observations, many individuals from this isolated population showed the same quality as some internationally recognized cultivars. Key words: Flowering periods, size, colour, strength, flavour of kernel, prospective elites. www.world-food.net Journal of Food, Agriculture & Environment Vol.6 (3&4) : - . 2008 WFL Publisher Science and Technology Meri-Rastilantie 3 B, FI-00980 Helsinki, Finland e-mail: info@world-food.net Introduction Persian walnut (Juglans regia L.) is commercially cultivated in many regions around the world for its timber, as well as for its nuts. European production of Persian walnut still largely depends on trees originated from seedlings. During the last 20 years, important work on seedling selection has been carried out in local populations of walnut throughout Europe. Also, the characteristics of wild walnut trees have been described in Bulgaria, Germany, Greece, Hungary, Italy, Poland, Portugal, Romania, Slovenia, Spain and the Ukraine 1-10 . In Romania over 85% of the yield is obtained on isolated walnut trees which can be found around houses or on private properties. Local populations present great genetic variability due to the method of seed reproduction, and also because of an intensive exchange of seminal material with Hungary, Austria and Serbia 3 . Phenotypes of the cultivars in Romania are described by their physical characteristics and named after the localities where they can be found, e.g., Sibişel 2, 3, 21, 22, 32, 34, 35, 39, 44, 45, 50 ; Geoagiu 1, 2, 53, 66, 67; Homorod 1 ; Gelmal 1 ; Romoşel 1; Apold 163; Crăciunel 1, 2, 3, 4 Meza 1, 3, 4, 6, 7, 8, 9, 10; Măgureni 3, 6; Rotunda de Satu Mare, Gubău 22; Gurbău 24; Sărmas 16; Cluj 8; Selistea 26, Cãtina 20; Bistriţa 3; Dumitra 2, 9; and Viisoara 10. Valuable edible nuts produced by walnut trees are well appreciated because they are rich in unsaturated fat (linoleic, oleic acid). They also contain other beneficial components like plant protein (e.g., arginine, leucine), carbohydrates (e.g., dietary fibre), vitamins (e.g., vitamin A, E), pectic substances, minerals (magnesium, potassium, phosphorus, sulphur, copper and iron), plant sterols and phytochemicals (phenolic acids, flavonoids etc.). Improved walnut cultivars require a well-sealed shell with a light- coloured kernel, free of flavours and comprising about 50% of the nut weight. Oil quality may be a concern in the future 11, 12 . From the consumer’s point of view (satisfaction and further consumption), the sensory properties of nuts are important, especially their visual and taste properties, which means sensory characterization is quite advisable 13 . Due to the variety of locations where the Persian walnut (J. regia) is cultivated in Eastern-Europe and Western-Asia, it is essential to know the biological characteristics and nut quality of the various prospective elites and cultivars. Some studies have shown that nuts obtained from the high-altitude locations were lighter-coloured and required more force to fracture the shells than those harvested at lower altitudes 14, 15 . The region of Eastern Transylvania where the investigation was carried out may be one of the coldest both in Romania and in UE (- 10 to -25 o C in winter and 25 to 30 o C in summer). Therefore, this isolated population, growing by seedlings, may be very resistant