Evaluation of rootstocks for Valencia and Navel orange trees in Saudi Arabia

Abstract

Introduction . Environmental conditions and cultural practices vary considerably from one region to another. Therefore, a long-term study was carried out to investigate the horticultural adaptability and performance of ‘Olinda Valencia’ and ‘Parent Washington Navel’ orange trees on nine commercial rootstocks in the Najran area of Saudi Arabia. Materials and methods . The trees were planted in 1987 with a (6.0 × 6.0) m spacing and a density of 278 trees·ha–1 . Fruit yield, fruit size, individual fruit weight, peel thickness, percent of juice, soluble solids and acid were measured. Results . Over the 7-year production period, trees on Volkamer lemon (VL), Citrus macrophylla (Cm ) and rough lemon (RL) were the most productive and trees on Cleopatra mandarin (Cleo) and Swingle citrumelo (Sc) were the least productive. Trees on Sour orange (SO), Amblycarpa, Carrizo citrange (CC) and C. taiwanica (Ct ) were intermediate in fruit production. The greatest fruit individual weight and largest fruit were found on trees budded on RL, VL and Cm , while the lowest fruit weight and smallest fruit were found on trees budded on Cleo and SO. Trees on RL had the lowest juice content. Fruit from trees on CC and SO accumulated the highest soluble solids and fruit from trees on Cm and Ct accumulated the lowest soluble solids. Valencia trees produced more fruit with higher juice content and soluble solids than Navel trees. Conclusion . Overall, trees on Swingle citrumelo and Cleopatra mandarin performed most poorly. Trees on vigorous rootstocks (Volkamer lemon, C. macrophylla , rough lemon) performed better and were more productive than trees on other rootstocks and Valencia trees were more profitable than Navel trees.