Optimization of NPK levels of Clementine Sidi Aissa (Citrus reticulata Blanco) trees grafted on different citrus rootstocks

F.E. Omari¹, L. Beniken¹, A. Zouahri², R. Mrabet³, H. Benaouda¹, R. Benkirane⁴ and H. Benyahia¹

¹Regional Center of Agricultural Research of Kenitra, National Institute of Agricultural Research (INRA), N°14, Ave. Abou Temmam mailbox: 257. Kenitra, Morocco
²Regional Center of Agricultural Research of Rabat, National Institute of Agricultural Research (INRA), Ave. Mohamed Belarbi Alaoui mailbox: 6356 – Institutes, Rabat Morocco
³National Institute of Agricultural Research (INRA), Rabat- Morocco. Ave. Ennasr mailbox: 415 RP Rabat Morocco
⁴Plant Productions, Animal and Agro-Industry Laboratory, Ibn Tofail University, Faculty of Science of Kenitra, University Campus, mailbox 133 Kenitra, Morocoo
*Correspondence: fatimaezahra.omari@inra.ma

Abstract:

The present study aims to investigate the impact of various nitrogen concentrations on young Clementine Sidi Aissa citrus trees (Citrus reticulata Blanco), grafted on five citrus rootstocks namely Moroccan Carrizo citrange, French Carrizo citrange, Troyer citrange, Citrus macrophylla, and sour orange (Citrus aurantium L.). The experiment took place in greenhouses at the Experimental station of El Menzeh INRA-Morocco, with the young trees grown in containers. We applied five different nitrogen treatments (expressed as mg L^-1 of N-P₂O₅-K₂O): (0–0–0), (0–25–50), (25–25–50), (50–25–50), and (100–25–50). The split-plot experimental design was used with three replications.

The findings demonstrate that the nitrogen enrichment resulted in enhanced plant growth, marked by increased plant height, rootstock and scion stem diameters, diameter and shoot length, relative water content (RWC), as well as leaf chlorophyll and proline content. Optimal growth of the Clementine Sidi Aissa trees was observed under the 100–25–50 (mg L^-1 of N-P₂O₅-K₂O) treatment.

The study also found that leaf nitrogen concentration increased in line with the quantity of nitrogen added, whereas the percentages of phosphorous and potassium in the leaves decreased. The most significant growth increase across the majority of the studied parameters was noted in Clementine Sidi Aissa trees grafted on Moroccan Carrizo citrange and Troyer citrange rootstocks.

Key words:

citrus, leaf nutrient, mineral nutrition, rootstock, vegetative growth