315 Journal of Nuts Journal homepage: ijnrs.damghaniau.ac.ir Journal of Nuts 11(4) (2020) 315-326 Phenotypic Evaluation and Identification of Superior Persian Walnut (Juglans regia L.) Genotypes in Mazandaran Province, Iran Mousa Kouhi 1 , Ali Rezaei 2 , Darab Hassani 3 , Saadat Sarikhani 4 , Kourosh Vahdati 4* 1 Department of Horticultural Science, Faculty of Agriculture and Natural Resources, Karaj Branch ,Islamic Azad University, Karaj, Iran 2 Department of Horticultural Science, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran 3 Temperate Fruits Research Center, Horticultural Science Research Institute, Agricultural Research, Education and Extension Organizations, Karaj, Iran 4 Department of Horticulture, College of Aburaihan, University of Tehran, Tehran, Iran A R T I C L E I N F O A B S T R A C T Keywords: Genetic diversity; Juglans regia L., Kernel percentage; Late-leafing; Superior genotypes Huge genetic diversity of Persian walnut in Iran provides a great opportunity for walnut breeders to use it for introducing varieties with desirable traits. In this regard, evaluating the genetic diversity and introducing superior genotypes is the foundation step of a walnut breeding program. This study was conducted to exploit the genetic diversity in Savadkuh county, Mazandaran province, Iran to identify some superior genotypes during 2013-2016. In the first step, 91 seed-originated genotypes were selected based on questionnaire. In the second stage, the morphological characteristics of the selected genotypes were studied using two IPGRI and UPOV descriptors in 2015. The results showed that nut and kernel weight ranged between 7.3-16.7 g and 3.2-8.6 g, respectively. Also, kernel percentage and shell thickness varied from 36 to 60.74% and from 0.8 to 2.8 mm, respectively. According to the morphological evaluation, 9 out of 91 genotypes (SR7, SR8, SR14, SR23, SR24, SR33, SR52, SR60 and SR83) were selected as superior genotypes. The selected superior genotypes were morphologically evaluated for two consecutive years (2015-2016). These superior walnut genotypes had high yield, lateral bearing habit (45-60%), heavy (13.4-16.7 g) and large nuts, high kernel percentage (48.6-56.6%), thin to moderate shell (1.1-1.6 mm) with light kernel color. Due to distinct and desirable characteristics, the selected superior genotypes can not only be used as parents in the further breeding program, but also some of them have the potential to release as commercial varieties. Introduction Persian walnut (Juglans regia L.) is a monoecious species with dichogamous habit which is grown in a wide range of temperate zone (Ebrahimi et al., 2009 and Bernard et al., 2020). Due to high amounts of unsaturated fatty acids, proteins and antioxidants compound in walnut kernel, demand for consumption and consequently demand for its production is rapidly rising (Ros and Mataix, 2006 and Sarikhani et al., 2021). According to FAO data, the world walnut production and area harvest were 4498442 tones and 1305349 hectares which has increased by 62.5% and 29.7% over the prior 10 years, respectively. China, USA * Corresponding author: Email address: kvahdati@ut.ac.ir Received: 31July 2020; Received in revised form:29 September 2020; Accepted: 5October 2020 DOI: 10.22034/jon.2021.1919541.1104 315