Vol.:(0123456789) 1 3 Horticulture, Environment, and Biotechnology (2023) 64:695–708 https://doi.org/10.1007/s13580-023-00511-4 REVIEW ARTICLE Salinity stress in date palm (Phoenix dactylifera L.): tolerance, mechanisms and mitigation Khalid M. Al‑Absi 1 Received: 15 July 2022 / Revised: 8 January 2023 / Accepted: 10 January 2023 / Published online: 1 April 2023 © The Author(s), under exclusive licence to Korean Society for Horticultural Science 2023 Abstract The salinization of soil and irrigation water is becoming an increasingly serious constraint for the cultivation of fruit crops, especially in arid and semiarid areas. The efect of salinity of diferent ionic compositions on date palm growth and toler- ance at diferent stages of growth and development has been described in this review; the tolerance is based on the type of salt stress: osmotic efect, specifc ion toxicity, and/or nutritional imbalance. Up to recently, the mechanisms underlying salt tolerance of date palms are far from being completely clarifed. In response to salinity stress, date palm adapts via diferent mechanisms, including ion homeostasis (Na exclusion by the root system and the ability to sustain a proper K/Na ratio), reactive oxygen species scavenging, and osmotic adjustment to limit water loss and protect the photosynthesis process. Much work is needed at the molecular and biochemical levels toward a full understanding of the mechanisms of salinity tolerance in date palms. The expression analysis of some genes (PdGLX1, PdPIP1;2, PdDJ-1 and PdVIK) promote date palm growth by enhancement of methylglyoxal (as toxic oxygenated short aldehyde) detoxifcation activity and decreasing the accumulation of reactive oxygen species under salt stress environment. The extent of tolerance mechanisms is strongly cultivar-specifc; so, supplementary research is required to recognize the genotypic variation in salt adaptation among date palm cultivars in the long term and thus start new breeding programs. The cyclic use of saline water and good quality water and avoidance of irrigating trees with high saline water at sensitive stages of growth are, also, good and safer strategies to reduce the negative impact of salt stress. Keywords Osmotic efect · Specifc ion toxicity · Ion homeostasis mechanism · Tolerance · Stress mitigation 1 Introduction Water scarcity; nearly always aggravate by low qual- ity pushes planners, and decision-makers more and more strongly to adopt water supplies from such non-conventional sources as saline irrigation water and wastewater. The prin- cipal criteria of water suitability for irrigation are sodicity, salinity, and specifc ion toxicity. Thus, the use of saline water and wastewater in agriculture is considered one of the alternative sources of irrigation water in countries, which sufer from a shortage of fresh water, such as Jor- dan and other Mediterranean countries. Salinity has been an important issue in the history of mankind and in agricul- tural systems upon which mankind has relied. It limits food production due to the damage efects of salts on plant growth caused by the physiological drought, specifc ion efect, and nutritional imbalance (Flowers and Colmer 2015). This warning is increasing in arid and semi-arid areas due to the frightening rise of global temperatures in addition to the inability of restricted precipitation to leach salts out of the root zone. Jordan is classifed as a semiarid region sufering from drought, where about 90% of its area receives a rainfall of about 200 mm or less. Date palm (Phoenix dactylifera L., 2n = 36) is an impor- tant dioecious evergreen perennial fruit tree grown in most countries of arid regions in the Middle East, where plants are often subjected to extreme environmental conditions. The date palm cultivation had begun in 4000 BC in Iraq (lower Mesopotamia) and 3000 BC in Nile Valley (Erskine et al. 2004). Date palm is a minor fruit crop grown in Jordan. Its cultivation covers less than 1% of the total area planted Communicated by Ali Sarkhosh. * Khalid M. Al-Absi absikhal@mutah.edu.jo 1 Department of plant production, Faculty of Agriculture, University of Mutah, B.O.Box 7, Mu’tah 61710, Jordan