Gestion Datiles

The response of date palm to calcareous soil fertilisation
H. A. Kassem1
1Plant Production Dept., College of Food and Agriculture Science, King Saud University, Saudi Arabia. hkassem39@yahoo.com

Abstract
An experiment was conducted during two successive seasons, 2008/2009 and 2009/2010, on the Zaghloul date palm cultivar grown in calcareous loamy sand and irrigated with drainage water. Thepurpose of the experiment was to investigate the effects of 1,000 g total N per palm applied as either ammonium sulphate, ammonium nitrate or urea and two levels of potassium (K2O) and elemental sulphur (S) on the nutritional status, productivity and fruit quality of the cultivar. The results of the study showed that the ammonium sulphate form (N1) increased the fruit yield, weight, length andcolour compared to the ammonium nitrate (N2) or the urea form (N3). Fruit TSS, sugars, anthocyanin and dry matter content increased, whereas fruit acidity and tannins decreased under N1 fertilisation. Furthermore, the potassium and sulphur fertilisation enhanced the physico-chemical characteristics of the fruit. The N1 application increased the leaf N, K, Ca, Fe and Zn contents, as did the potassiumand sulphur application. The N1 application increased the fruit N, P, K, Fe and Zn contents, whereas the fruit Cd, Pb and NO3 were highest with N2. The potassium and sulphur applications increased the fruit N, Fe, Mn, Cd, Pb and NO3 contents.
Keywords: Fertilisation; Calcareous Soil; Drainage Water; Date Palm.

1. Introduction
Date palm (Phoenix dactylifera) is the most common fruit tree grownin semiarid and arid- regions of the Middle East and North Africa. In Egypt, many farmers rely on date palm cultivation. According to FAO (2010), Egypt is considered the leading country among the top ten date producers (1,130,000 tonnes). Date palm fruits are one of the most important export fruit crops in Egypt, where they are harvested and marketed at three stages of their development. Thethree stages are khalal (bisr), rutab and tamar. Dates in the khalal stage appear first in the harvesting season and therefore find a ready market. The best date varieties suitable for marketing at the khalal stage are Zaghloul dates, which are the most economically important soft cultivars grown in Egypt. Generally, they are grown and are highly productive under stringent environmental conditionsthat may be not suitable for many other species of fruit trees. The palms investigated in the present study were grown in loamy calcareous soil and irrigated with drainage water. These conditions strongly influence the amount of nutrient uptake. Therefore, the adaptation of a proper fertilisation program, including adequate rates, appropriate sources and efficient application methods and timing areimportant strategies for obtaining better yield and fruit quality (Fageria and Baligar, 2005).
Nitrogen is known to be one of the most important elements for plant nutrition and development because it plays an important role as a constituent of all proteins, nucleic acids and enzymes (Nijjar, 1985). The forms and levels of nitrogen, the cultivars considered and the physico-chemical properties ofthe soil are all related to the use of nitrogen by plants (Li et al., 2007). The form of nitrogen applied can play a significant role in plant growth and productivity (Sady et al., 2008). Ammonium (NH4+), nitrate (NO3-) and urea are the forms of nitrogen generally applied. Different nitrogen sources may be preferred for use with different plant species (Marschner, 1995). The responses of a largenumber of fruit trees to the application of different nitrogen forms have been reported previously (Saleh et al., 2000).
Potassium is also an important nutrient for date palm growth and productivity (Al-Kharusi et al., 2009). Potassium is necessary for basic physiological functions, such as the formation of sugars and starch, the synthesis of proteins, cell division and growth, fruit formation...