Walnut cultivars in the sub-carpatian area of Oltenia

Advantages and disadvantages offered by growing lateral bearing walnut cultivars in the sub-carpatian area of Oltenia. Mihai Botu, Ion Botu, Maria Tudor, Papachatzis Alex Universitatea din Craiova - SCDP Valcea Tehnological Education Institution of Larissa Abstract. Romania is a country where walnut culture has tradition. This fruit crop has good productive potential but it is necessary to grow adequate cultivars in concordance with the ecological conditions and market demands. Lateral bearing walnut cultivars are grown in many countries due to their productivity and precocity. For this reason, cultivar testing program carried out at SCDP Valcea from 1994 was focused also on introduction and evaluation of lateral bearing walnutcultivars from abroad in order to establish the most appropriate Romanian and introduced cultivars to be grown in the sub-Carpathian area of Oltenia. Laterar bearing walnut cultivars proved to be precocius regarding their coming into production, also the yields obtained were upto 40% higher in the case of ’Ferjean’, ’Vina’, ’Hartley’ and ’Lara’ comparatively with ’Franquette’, which was used as control. These cultivars showed higher susceptibility to bacterial blight then’Franquette’ and Romanian cultivars in the sub-Carpathian area of Oltenia ecological conditions. Keywords: walnut, Juglans regia, cultivars, evaluation Cuvinte cheie: nuc, Juglans regia, soiuri, evaluare 1. Introduction. There are many cultivars of walnut (Juglans regia L.) worldwide with very different characteristics agrobiological characteristics, these cultivars offer a choice for the most valuable in terms of production,fruit quality, adaptation to different environmental conditions, etc. The research work conducted in different ecological zones of the world have shown how the specific behavior of each kind of walnut cultivar in accordance with its genotype under the given environmental conditions (Ramos, 1985; Aleta and Ninot, 1997; Botu, 1998; Germain et al, 1999; Botu et al., 2000; Cociu et al., 2003; Tudor, 2010). In Romania, a country with tradition and production potential in walnut culture, the research activity has been directed towards the assessment of domestic and foreign cultivars with terminal bearing. These cultivars are less productive, but adapted to the ecological conditions in the areas with vocation for this fruit crop culture and vocation and less susceptible to diseases; they cultivars have encountered plenty of difficulties for several reasons in order to be promoted into culture in fruit farms (mainly due to difficulty of grafting propagation). The lateral bearing cultivars were extended in many countries, but their requirements for certain environmental conditions and technological level needed for their growing diminish the advantages brought by them through high productivity. The research conducted at SCDP Vâlcea on some lateral bearing walnut cultivars of different geographical origin aimed to evaluate them and to highlight the advantages and disadvantages of their growing into the sub-Carpathian region of Oltenia. 2. Materials and methods. The research activity on this topic at SCDP Valcea was conducted from 1994 to 2009 and was based on the study of 10 lateral bearing walnut cultivars which were compared with ‚Franquette’, an old French variety with terminal bearing, which was used as control. The cultivars which were studied have different geographical origin and are most popular worldwide: ‚Ferjean’, ‚Fernette’, ‚Fernor’, ‚Lara’ (from France) and ‚Hartley’, ‚Payne’, ‚Pedro’, ‚Tehama ‚, ’Serr’ and ‚Vina (from USA). ‚Franquette’ (originated in France) is the most popular walnut variety grown in many countries, this cultivar has terminal or standard bearing. All the cultivars from this study have been grafted on Juglans regia seedlings. Planting was done at 9 m by 8 m (139 trees per hectare). Each cultivar was represented by five trees. The trees were trained as a mixed pyramid and were anually fertilized with 100 kg of N, 20 kg of P and 40 kg K, phytosanitary–spraying were done in accordance with Vâlcea Plant Protection Inspectorate warnings. Observations and measurements were carried u ton trees’ growth and yielding. 3. Results and discussions. The behaviour of lateral bearing walnut cultivars and the results obtained were dependent on technological and climatic conditions of the sub-Carpathian region of Oltenia. The climate of this area is mild continental with Mediterranean influences. In 112 years time the annual average temperature was 10.2°C, the absolute minimum one of – 27°C (in 1967) and the annual amount of rainfall of 712 mm. During the study of fructification time of the walnut cultivars (1996-2009 period) the annual average temperatures have fluctuated between 9.8°C (in 1997) and 12.0°C (in 2007 and 2009). The lowest absolute minimum temperature was – 22.7°C (in 2006), in the other years during study period temperatures did not go below -16°C. In the first days of April minimal temperatures of – 5°C,- 6°C were recorded, but did not affect the flowers and shoots’ development. The rainfall ranged from 493 mm (2008) to 1085 mm (2005) per year, registering a substantial deviation from the normal rainfall quantity of the area. Taking into account this determinant context of climatic conditions, the lateral bearing walnut cultivars had a trunk cross sectional area (TCSA) ranging from 518 cm2 (‚Pedro’) to 665 cm2 (‚Tehama’), much lower than the terminal bearing cultivar ‚Franquette’ (742 cm2) used as control. All the cultivars which have terminal bearing differ very significant negative or distinct significantly negative compared with ‚Franquette’. The crown volumes ranges from 118.8 m3 (‚Ferjean’) to 165.8 m3 (‚Tehama’). Crown volume of these varieties differ significant distinct