Genetic diversity collected and observed in Persian Walnut ("Juglans regia" L) in the Western Himalaya region of India

espanolEl Himalaya occidental es la principal region productora de nogales de India, con la mayor variabilidad de la especie. El nogal persa (Juglans regia), la especie de mayor importancia comercial, es alli la unica. En cinco anos (1999-2004) se realizaron siete expediciones para recoger plasma germinal, marcandose 182 arboles en 48 sitios. Se evaluo la gama y patrones de diversidad genetica, examinando los problemas y perspectivas del cultivo de nogales. Se estudio la variabilidad de caracteres de nueces y almendras, registrandose una amplia variabilidad fenotipica. Se identificaron ubicaciones con altos niveles de variacion fenotipica atribuible al origen de los plantines de nogal. Los hallados a 1500 y mas metros de altura eran de mayor calidad (nueces de color claro y cascaras delgadas) que los de alturas menores. El cultivo de nogales decae por la baja productividad de un material de plantacion de poca calidad, escasa polinizacion, baja densidad de arboles por unidad de superficie, predomio de carga terminal, prolongado periodo juvenil, gran tamano de los arboles, escaso rellenado, poco exito de los injertos y fluctuaciones climaticas. Pero la region podria producir nogales de gran calidad por sus apropiadas condiciones agroclimaticas. Se deben seleccionar o criar variedades que combinen rasgos deseables: pequeno tamano, breves periodos juveniles, precocidad, mejor indice nuez-almendra y carga lateral. El plasma germinal disponible en la region posee casi todos los rasgos necesarios para cultivar variedades de nogal que combinen estas caracteristicas. EnglishThe Western Himalaya is the major producer region within India for walnut and contains maximum variability for the species. The most commercially important walnut species, Persian or English walnut (Juglans regia), is the only species found in the region. This study was conducted to assess the range and patterns of genetic diversity in the region, and also to study the problems and prospects for growing walnut. Seven germplasm collection trips were undertaken in five consecutive years (1999–2004) throughout the region, and 182 trees were marked at 48 sites. Variability was studied for nut and kernel characters, and a wide range of phenotypic variability was recorded. Sites with high levels of phenotypic variation in walnut characters were identified. The observed high phenotypic variation in walnut plantations in the region is attributable to their seedling origins. Walnuts found at altitudes of 1500 m and above were superior in quality (light-coloured kernels and thin shells) compared with those found at lower elevations. Walnut cultivation was found to be declining, mainly due to factors such as low productivity arising from a lack of good quality planting material; poor pollination; low tree density per unit area; predominant terminal bearing; long juvenile period; big tree size; poor filling; poor success rate of grafting; and climatic fluctuations. Nevertheless, the region has potential to produce high quality walnuts as it possesses suitable agroclimatic conditions. Varieties combining desirable traits, such as dwarf stature, shorter juvenile period, earliness, better nut-kernel ratio and lateral bearing need to be selected or bred and made available to farmers. The walnut germplasm available in the region possesses almost all the desirable traits needed to breed varieties combining these traits francaisL’Himalaya occidental est la principale region productrice de noix en Inde, l’espece la plus importante du point de vue commercial etant le noyer royal (Juglans regia). Cette etude a ete realisee pour evaluer l’amplitude et les profils de diversite genetique dans la region ainsi que les perspectives de culture du noyer. Sept missions de collecte de materiel genetique ont ete entreprises entre 1999 et 2004 sur 182 arbres dans 48 sites. La variabilite phenotypique (noix et amande) est attribuable a l’origine des plantules. Les noyers observes aux altitudes de 1500 m et au-dela ont une qualite superieure (amande de couleur claire et coque mince) par rapport a ceux qui se developpent a plus faible altitude. Plusieurs facteurs expliquent la faible productivite qui a entraine un declin de la culture du noyer : mediocre qualite des jeunes plants, mauvaise pollinisation, faible densite des arbres, predominance des varietes a fructification terminale, longue periode juvenile, grande taille des arbres, proportion elevee de noix creuses, faible taux de reussite des greffes et fluctuations climatiques. Neanmoins, les conditions agroclimatiques de la region conviennent a la production de noix d’excellente qualite. A cet effet, il est necessaire de selectionner et de mettre a la disposition des agriculteurs des varietes reunissant les caracteres souhaites (nanisme, brievete de la periode juvenile, precocite, meilleur rapport noix-amande et fructification laterale) en partant du materiel genetique disponible dans la region