Improving Fruit Quality and Nutritional Value of Deglet Nour dates subjected to Salt Stress by using Phospho-Potassium Fertilization (Biskra south-east of Algeria)
Abstract
Afield study was carried out during the two consecutive years (2015-2016) in the region of Biskra, southern east of Algeria on date palms of Deglet-Nour variety, grown in a salty environment. To study the combined effect of salinity and phospho-potassium fertilization on the quality and nutritional value of dates, two sites of different salinity, occupied by 54 date palms variety Deglet-Nour has been selected. The palms were fertilized by receiving three doses of potassium (0, 2 and 3 kg / palm) as potassium sulphate K SO (50%) combined with three levels of phosphorus (0, 1 and 2 kg / palm) as 2 4 superphosphate (TSP 46%). The results revealed that applying 2 kg of potassium/palm in an excessively salty environment and 3 kg/palm in alow or unsalted environment associated to 1 kg of phosphorus in the two different cases of salinity of the two sites S1 and S2 improving the fruit traits.
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Introduction
The problem of salinity is multiple, because in addition to the toxicity of Na+ and Cl-ions (dissolved in the irrigation water or present in the soil solution) and the perturbations of the mineral nutrition (following the interactions between ions), plants have difficulty absorbing soil water because of its high osmotic pressure, and this is justified by water stress in addition to salt stress, thus complicating and altering their physiological state exponentially and causing multiple perturbations on the metabolism, growth and development of plants at the molecular, biochemical and physiological levels (Winicov 1998 Munns 2002, Tester and Davenport 2003).
In arid regions in addition to drought and heat that inhibits growth and productivity of the date palm saline stress mainly affects its vitality. Furr (1975) reported that it is evident that the date palm is more salt tolerant than barley and that it can be the most salt-tolerant of all cultivated plants but increasing soil salinity is beginning to have a negative impact on the agro-ecosystem of date palm in the arid region, particularly in the Middle East (Dakheel, 2005). In Algeria in the Ziban oases (Biskra region) mismanagement of irrigation and drainage water has detrimental consequences on the phoenicultural environment (Munier, 1973), it has led to soil salinization, falling yields and poor-quality dates (Dutil, 1971; Dubost, 1991). Relative yields become null if the farmer uses salted soils by the usual method and it allows to obtain some harvests, but extremely low and of poor quality because of the salt content.
In the context of improving fruit quality and the nutritional value of Deglet Nour dates, phospho-potassium fertilization is considered an important factor that affects fruit quality and date palm productivity.
The objective of this study is to spatialize salinity, characterize soil in an irrigated palm grove and then adapt a phospho-potassium fertilization program aimed at improving the production and quality of Deglet-Nour dates grown in saline soil.
Conclusion
It is therefore necessary to emphasize that date palms, like other trees, need to be fertilized, especially since the palm tree needs nutrients continuously without any specific period, because its growth continues throughout year. At the end of this study, we were able to highlight the effect of phospho-potassium fertilization in improving date quality as an integrated action to minimize the consequences of different constraints.
The quality of the dates obtained in this study complies with the criteria for the qualitative evaluation of dates of Algerian, Moroccan, Tunisian, Egyptian and Iraqi cultivars reported by Rygg, (1953);Meligi and Sourial, (1982) and Mohamed et al, (1983); Rayens et al (1994);Othman (1995).
To improve the quality and nutritional value of the fruits, it is recommended to apply 2kg of potassium sulphate/palm in an excessively salty environment and 3kg/palm in a non-salty environment with 1 kg of phosphorus in both situations.
