Improving Yield, Fruit Quality and Leaf Mineral Content of Navel Orange Trees with Natural Elements Compound (NEC) and Cobalt Applications

摘要

The aim of this work was to study the effect of different Natural Elements Compound (NEC) and cobalt levels on yield, fruit quality and leaf mineral content of Navel orange trees. This study was carried out through two successive seasons (2012 and 2013) in a private orange orchard in Qalubia Governorate Egypt on 40 years old Navel orange trees budded on sour orange rootstock on clay loam soil (Typic Torriorthents). Planting distance was 5 x 5 meters apart and surface irrigation was used by River Nile water. The experiment included three levels of Natural Elements Compound (NEC) (NE1= 0, NE2= 2.5 and NE3=5.0 Kg/ tree/ year as soil application) and four levels of cobalt (B1=zero, B2=10, B3=20 and B4=30 ppm Co as foliar application). Thus the experiment was laid out in factorial experiment in a randomized complete block design. Results showed that, NE2 (2.5 kg/tree/year) was sufficient for gave the high values of yield, fruit physical and chemical properties. On the other hand, yield, TSS and TSS/acid ratio were gradually increased by increasing cobalt level up to 10 ppm and/or 20 ppm. The combination between (NEC) and cobalt levels, the highest values of yield were obtained by treatment (NE2x B4) and (NE3x B3). Regarding leaf nutrient content, results pointed out that (NEC) levels affected nutrient content considerably. In most cases, level NE2 (2.5 kg/tree/year) gave more or less similar values as those of level NE3 (5.0 kg/tree/year) for N, P, K, Fe, Zn, Mn and Co content. On the other hand, the third level of cobalt B3 (20 ppm Co) gave the highest values than those of other levels especially for P, K, Zn and Mn. Regarding the interaction between (NEC) and cobalt levels, it could be concluded that, combining (NEC) with cobalt creates slightly more appreciable effect on macro- and micronutrients content of Navel orange trees than untreated trees (NE1x B1). Meanwhile, high values were obtained almost when combining the second and third levels of (NEC) with the (B2, B3 and B4 levels). The highest values were obtained by treatments (NE2x B3) and (NE3x B3) for K, Fe, Zn and Mn. Therefore, using treatment (NE3x B3) may be recommended as good treatment for enhancing Navel orange yield, fruit quality and leaf mineral content especially under old citrus orchards.