Nutrient Diagnosis Norms for Date Palm (Phoenix dactylifera L.) in Tunisian Oases

Abstract

Several studies have pointed out the promising use of nutritional diagnosis methods for the determination of optimum nutrient contents in plant tissues. The present investigation was carried out in different oases in Southern Tunisia to determine reference values for the interpretation of leaf analyses of date palm (Phoenix dactylifera) Deglet Nour cultivar with the Critical Value Approach (CVA) and the Compositional Nutrient Diagnosis (CND). A database (n = 100) of yield and mineral concentrations taken from date palm leaflets in October, at the maturity stage of dates, was used. The yield cut-off between low-yield and high-yield subpopulations, selected from cumulative variance ratio functions across survey data, was 76 kg palm−1 and the global nutrient imbalance index (CNDr2) was 10.06. Critical CND nutrient indices were found to be symmetrical around zero as follows: (1.59; +1.59) for IN, (−0.44, +0.44) for IP, (−0.63, +0.63) for IK, (−0.94, +0.94) for ICa, (−1.05, +1.05) for IMg, (−0.80, +0.80) for IFe, (−0.74, +0.74) for ICu, (−0.80, +0.80) for IB, (−0.93, +0.93) for IZn, (−1.04, +1.04) for IMn, and (−1.03, +1.03) for the residual value. Compared to CND, the CVA approach shows weak detection of the nutrients that cause nutritional imbalance. CND indices revealed, except for N, the presence of nutrient imbalances and the necessity to correct the mineral nutrition of date palm in the Kebeli oases.

Compositional Nutrient Diagnosis (CND) Standards for Opuntia ficus-indica (L.) Miller 'Rojo Pelón' Fruiting

“…On the other hand, the DRIS and CND approaches involve nutrient interactions (Bhaduri and Pal, 2013). Various authors indicate that there are little differences between DRIS and CND for establishing nutrient norms (Khiari et al, 2001b;Barłóg, 2016;Mostashari et al, 2018;Barros de Morais et al, 2019;Bendaly Labaied et al, 2020). Nonetheless, other researchers endorse the CND arguing that it is more efficient to determine the nutritional status of crops because of its sound mathematical and statistical bases (Kumar et al, 2003;Blanco-Macías, 2009;René et al, 2013;Valdez-Cepeda et al, 2013;Barros de Morais et al, 2019).…”

“…Up to now, CND norms for nutrient status diagnosis have been developed for various crops such as Carya illinoinensis (Wangenh.) K. Koch (García-Hernández et al, 2009), Aloe vera L. (García-Hernández et al, 2006), Coffea arabica L. and Coffea canephora Pierre ex A. Froehner (Wairegi and Van Asten, 2012), Phoenix dactylifera L. (Bendaly Labaied et al, 2020), Vitis vinifera L. (Mostashari et al, 2018), Eucalyptus grandis W. Hill ex Maid. (Costa da Silva et al, 2004;Barros de Morais et al, 2019), Zea mays L. (Khiari et al, 2001a;Magallanes-Quintanar et al, 2006), Musa spp.…”