Impact of Salinity Stress on Date Palm (Phoenix dactylifera L) – A Review

Abstract

The growth and productivity of palms are primarily affected by salinity stress in the arid regions apart from drought and heat. The world scenario on salinity problems is critical, over 20 percent of the cultivated area and half of the irrigated land in the world is encountering salinity stress of different magnitudes. The importance of date palm culture for its high nutritive, economic and social values is well recognized, especially in arid and semi-arid areas where it plays an important role influencing microclimate in a way that enhances the production of other agricultural crops. Worldwide production, utilization and industrialization of dates are increasing continuously (Botes and Zaid 2002). Different productivity parameters such as germination of seeds, seedling growth, vigor, reproductive flushing and fruiting are adversely affected reflecting on optimum production and productivity. The basic cause of salinity hazards is enhanced ion toxicity causing impaired sequestering of sodium ions into the vacuoles. The increased ionic concentration of the soil solution decreases the osmotic potential of the soil creating severe water stress derailing the uptake process. This can create imbalance in the absorption process of other minerals. In order to achieve salt-tolerance, the foremost task is either to prevent or alleviate the damage, or to re-establish homeostatic conditions in the new stressful environment (Parida and Das, 2005). The date palm growth and production in the arid regions is adversely affected by salinity problems apart from other crops like vegetables and fruits (Figures 1 & 2). Date palm is considered as the subsistence crop of the Middle East and North Africa. Despite date palms outstanding agronomic and socio-economic significance, attempts to use date palm biodiversity to screen against salinity tolerance have been limited and therefore of urgent priority. Although potential salt tolerant cultivars are available, there is no systematic approach to characterize such genotypes employing molecular diagnostic techniques. The understanding of the molecular, physiological, biochemical basis and soil factors will be helpful in developing selection strategies for improving salinity tolerance. Therefore pooling the information through the present review on salt responses in relation to various factors is crucial in developing strategies and improving salt tolerant mechanism in date palms. The review article covers the different aspects under the various growth stages of date palm, like seedling, vegetative phase and reproductive phase. The review also focuses on the use of remote sensing technology in date palm responses to salinity.