Deglet Nour date palm ( Phoenix dactylifera L.) is a key cultivar for Algerian date production, particularly in the Tolga oasis. However, increasing climatic variability threatens fruit quality during late maturation stages. This study assessed the impact of late-season climatic anomalies on fruit disorders across the khalal, rutab, and tamr stages, based on field observations, climatic data, and grower surveys conducted over three consecutive seasons (2023–2025). Climatic conditions between 16 August and 30 September were analyzed alongside systematic field observations. Marked interannual variability was observed. The 2023 season was characterized by extreme heat, low relative humidity, and moderate wind, coinciding with widespread fruit bunch wilting during the rutab stage. In contrast, the 2024 season exhibited higher atmospheric humidity and early rainfall events, associated with severe fruit rot during the tamr stage. The 2025 season showed more balanced climatic conditions and a low incidence of fruit disorders. Survey data supported these findings, with 78% of growers reporting significant wilting losses in 2023 and 61% reporting severe fruit rot in 2024, while both disorders were minimal in 2025. The consistency between climatic records, field observations, and growers’ perceptions suggests that these disorders are primarily climate-driven. Additionally, cultivar-specific traits, particularly the long bunch structure of Deglet Nour, may increase sensitivity to heat stress. These findings highlight the vulnerability of Deglet Nour fruit quality to climatic extremes and emphasize the need for adaptive management strategies to improve resilience under arid conditions.

This study reports the first documented occurrence of double-seeded fruits (DSF) in date palm (Phoenix dactylifera L.), a phenomenon distinct from previously described polyembryony. DSF were observed only in the cultivars ‘Kentichi’ and ‘Deglet nour’, where they occurred at very low frequencies (2.8 × 10−3% and 1.6 × 10−4%, respectively). Morphological observations indicate that DSF arise through partial or complete fusion of two carpels, resulting in syncarpic fruits that are significantly heavier and wider than single-seeded fruits, while fruit length remains unchanged. Germination rates were high and similar in both groups, but seeds from DSF germinated 8 days earlier than those from single-seeded fruits. In contrast, seedlings derived from DSF showed slower early growth. These findings identify DSF as a rare, genotype-dependent developmental variant in date palm and suggest that syncarpy influences fruit morphology, seed allocation, and germination behaviour.

Date palm cultivation is vital for sustaining agricultural economies in arid regions, where efficient pollination is essential for optimal fruit yield and quality. This study analyzed 47 morphological parameters in 10 date palm pollinators, including 32 vegetative and 15 reproductive traits, which were treated separately. The correlation matrix revealed strong positive correlations, such as pollinator vigor with palm angle and cornaf persistence with fibrillium hardness. Principal component analysis (PCA) identified eight highly discriminating vegetative traits (e.g. total palm length, palm angle) and six reproductive traits (e.g. spathe length, spikelet number). Genetic distance analysis showed close values (0.233–0.25), thereby indicating significant morphological diversity. Hierarchical classification grouped genotypes based on phenotypic similarities, with vegetative traits exhibiting greater dissimilarity (0.225–5.85) than reproductive traits (0.1–3.85). Heatmap analysis revealed that dense crowns correlated with long spikelets, while wide spines were associated with dense inflorescences. These findings underscore the importance of morphological traits for selecting and distinguishing pollinators, enhancing pollination efficiency, and ensuring sustainable production in date palm-dependent regions.

This study was conducted to investigate morphological and biochemical characteristics and potential for in vitro regeneration of the elite and extremely rare Tunisian date palm cultivar ‘Boufeggous’ grown at Tozeur oasis. The results revealed that ‘Boufeggous’ dates are heavier (19.83 versus 11.95 g), longer (50.1 versus 42.76 mm), wider (23.3 versus 18.63 mm), and higher pulp/fruit ratio (91.96 versus 89.06%) than ‘Deglet Nour’. Chemical composition study showed that ‘Boufeggous’ is predominantly rich in sugar and total soluble solids which could explain its unique sweetness and high energy value. The moisture content, pH level, titrable acidity and water activity were 23.16 ± 0.54, 5.3 ± 0.13, 1.7 ± 0.01 and 0.73 ± 0.01, respectively. In terms of minerals, ‘Boufeggous’ is rich in K and Na. In vitro regeneration on Murashige and Skoog (1962) medium comprising 1 mg/l 2,4-Dichlorophenoxyacetic acid appears to be the most effective stimulant of somatic embryogenesis and shoot organogenesis on both shoot tips and young leaf explants. Thidiazuron only acts on young leaves by stimulating embryogenic callus production with a frequency of 30%.

A stable tetraploid date palm mutant with the potential for increased fruit size was recovered from a sectorial di-tetraploid chimera via the in vitro culture of flower explants. Callus was induced using 2,4-D, followed by shoot regeneration on a medium containing NAA and BAP and rooting with IBA. Regenerated plantlets, confirmed as tetraploid via flow cytometry, were acclimatized and grown for six years. The leaves of tetraploids exhibited significantly wider petiole bases, thicker rachis and spines, broader leaflets, and a more intense green leaf color compared to diploids. However, leaf length, spine count, and overall leaf number were reduced. This is the first report of successful tetraploid recovery from a chimeric date palm, demonstrating the potential of this technique to generate novel germplasm and highlighting the phenotypic differences associated with tetraploidy in this species.

Date palms are a vital part of oasis ecosystems and are an important source of income in arid and semi-arid areas. Crossbreeding is limited due to the long juvenile stage of date palms and their dioecious nature. The aim of this study was to create triploid date palms to obtain larger and seedless fruits and to increase resilience to abiotic stresses. A tetraploid date palm mutant was crossed with a diploid male palm, yielding hundreds of seeds suspected of containing triploid embryos. Six years after planting, four palms with confirmed triploidy reached maturity. They are phenotypically distinct from diploids, with a thicker rachis, thinner spines, wider and longer midleaf spines, and a longer apical spine. They were classified as sterile bisexual, sterile male and fertile female. One of the latter produced very tasty dates with a very small seed, which is promising for the marketability and profitability of date palm fruits. This first report on triploid date palms provides a way in which to make a significant leap forward in date palm breeding. Given the vigor and fruit quality of female triploid date palms, compared to their diploid counterparts, they will be the target of breeding programs and may spearhead new oases.

Since 2017, a new leaf wilt syndrome was observed in plantations of date palm in Tunisia. Its incidence increases sharply from year to year, especially in 'Deglet Nour' trees, aged between 5 and 15 years. In severe cases, the large number of dried leaves per tree can lead to complete cessation of date production. Symptoms appear on one or more leaves in the center of the crown. Whitening and drying start at the top of the leaflets and proceed to their base, while the midrib remains green. Then the whole leaf dies. Small white-creamy leaflet fragments and roots were collected from five different regions in the Djerid Oases. They were disinfected with diluted bleach (0,8 % NaOCl) and ethanol (80%) (each 2 min), rinsed with sterile distilled water, dried and finally plated in Petri dishes containing Potato Dextrose Agar (PDA) amended with 50mg/l neomycin. After incubation for 7 days at 25ºC±2, emerging fungal colonies were single-spored by serial dilution. They were transferred to PDA, Carnation Leaf Agar (CLA) and Spezieller Nahrstoffarmer Agar (SNA) for morphological identification. Based on the colony color on PDA, conidial morphology and phialide structures on CLA and/or SNA, of the 85 Fusarium isolates, around 90% were identified as F. proliferatum and around 10% as F. brachygibbosum (Leslie and Summerell, 2006). Fusarium proliferatum colonies rapidly developed white aerial mycelium that became purple in old cultures. Microconidia were abundant in the aerial mycelium and formed chains of variable length, on monophialides and polyphialids, a characteristic that distinguishes F. proliferatum from F. verticilloides. Less often, they were observed in false heads. Chlamydospores were absent. On CLA, microconidia were mostly 2 × 15 µm in size, a large number of sickle shaped macroconidia (2 × 25 µm) had one septum, some were larger (2 × 50 µm) with 3 septa and tips at both ends. Molecular identification was carried out based on elongation factor (EF-1α) gene sequencing. The region between the EF1 and EF2 primers (O'Donnell et al., 1998) was amplified and the sequences were compared to Fusarium reference sequences (GenBank). The sequences of the isolates Fus 1953 (539 bp), Fus 1962 (618 bp), and Fus 1965 (605 bp) shared respectively 100%, 99.51% and 99.51% homology with that of F. proliferatum JF740713.1 and were deposited in GenBank with the following accession numbers: MT630418, MT630419, and MT630420, respectively. The sequences of isolates 7F, 28F, Fus 1955 and Fus 1956 shared 100 % homology with that of F. brachygibbosum (GQ505418.1) while those of Fus 1955 and Fus 1956 showed 99.02 and 98.91 % identity, respectively, with F. brachygibbosum JX118981.1. The sequences of 7F (535 bp), 28F (535 bp), Fus 1955 (608 bp), and Fus 1956 (647 bp) were deposited in GenBank with the following accession numbers: MT630409, MT630410, MT630411, and MT630412, respectively. Two ml suspension of 106 conidia / ml of each isolate was sprayed separately or in combinations on in vitro cloned 'Deglet Nour' plants, placed in a greenhouse at 28°±2 °C and 70% R.H.. Isolates of F. proliferatum led to dryness and wilting leaflets after 3 weeks. Fusarium brachygibbosum only induced mild leaf yellowing, while in combination they were more virulent. Fungal isolates of both species were re-isolated and their identity confirmed to be the same of those isolated from leaflets infected in the open field, confirming Koch's postulates. Control plants lacked symptoms. Fusarium proliferatum is known as date palm pathogen in many countries (Saleh et al. 2017), however, to our knowledge, this is the first report of F. proliferatum and also F. brachygibbosum causing Leaf Wilt symptoms on P. dactylifera in Tunisia.

This study addresses the development of unpollinated and pollinated flowers of date palm (Phoenix dactylifera L.). cv. Deglet Noor in three successive seasons (2015-2017), focusing on the physico-chemical characterization and functional properties of fruits at Kimri stage. Results showed for the first time that dropped fruits at Kimri stage have a clear beneficial action on human health compared even with Tamar stage, given its higher total polyphenols and antioxidant activity, 3 and 34 times superior to Tamar stage, respectively.

In the oasis of Tozeur (Tunisia) a peculiar date palm ploidy chimera was discovered, showing a diploid (2n =2x) and a tetraploid (2n =4x) sector and a uniform tetraploid offshoot.This chimera allowed to describe the effects of chromosome doubling on some selected features.Because both ploidies occur within one plant, there was no environmental bias.Tetraploid leaves are longer, bear larger leaflets and spines and have a thicker rachis than normal diploid leaves.During three seasons, tetraploid inflorescences appeared ten days later than their diploid counterparts.The tetraploid sector formed bunches with stalks bearing larger fruits, with a higher percentage of inedible parthenocarpic fruits, than bunches that arose from the diploid sector.Tetraploid fruits are significantly longer, wider and heavier than diploid fruits, with a larger pulp diameter, irrespective of whether they are seeded or parthenocarpic.Diploid parthenocarpic fruits are longer than seeded fruits, while tetraploid parthenocarpic and seeded fruits both show the same size.The occurrence of tetraploidy opens new perspectives in date palm breeding.Pollination of tetraploid pistils with pollen from diploid males gave rise to a relatively low number of triploid plantlets, suggesting a triploid block.

The date palm (Phoenix dactylifera L.) is dioecious with male flowers deficient in functional gynoecium and female flowers deficient in functional androecium borne on separate palms. The presence of male and female flowers on the same plant, a phenomenon known as monoecy, is unusual in male date palms. This study reports for the first time on hermaphrodite (bisexual) flowers borne by two female date palms, 'Alligue', that were found growing in an open field in Degache, southern Tunisia. The observations on these two female palms were compared with hermaphrodite male date palms growing in the same location. Hermaphrodite female date palm inflorescence branches bear female flowers predominantly near their base, in contrast to the hermaphrodite flowers that are found primarily toward their upper part. The position of the hermaphrodite flowers in hermaphrodite male date palms is reversed: inflorescence branches bear male flowers toward the upper part while the hermaphrodite flowers are found at the base. Histological examination of female hermaphrodite flowers revealed that they had three carpels and 1-6 stamens. Hermaphrodite flowers on male plants were usually also composed of three carpels of variable size, and six stamens. Hermaphrodite flowers on both female and male palm trees turn generally into parthenocarpic fruits. The present data support the theory that dioecious plants are derived from a common hermaphrodite ancestor. Floral hermaphroditism in date palm should be investigated in relation to the in planta self-fertilization process to identify sex markers and genes that control sex organ development.

The temporary immersion system (TIS) is being used with tremendous success for automation of micropropagation of many plant species. TIS usually consists of a culture vessel comprising two compartments, an upper one with the plant material and a lower one with the liquid culture medium and an automated air pump. The latter enables contact between all parts of the explants and the liquid medium by setting overpressure to the lower part of the container. These systems are providing the most satisfactory conditions for date palm regeneration via shoot organogenesis and allow a significant increase of multiplication rate (5.5-fold in comparison with that regenerated on agar-solidified medium) and plant material quality, thereby reducing production cost.

Background and Aims Date palms (Phoenix dactylifera, Arecaceae) are of great economic and ecological value to the oasis agriculture of arid and semi-arid areas. However, despite the availability of a large date palm germplasm spreading from the Atlantic shores to Southern Asia, improvement of the species is being hampered by a lack of information on global genetic diversity and population structure. In order to contribute to the varietal improvement of date palms and to provide new insights on the influence of geographic origins and human activity on the genetic structure of the date palm, this study analysed the diversity of the species.Methods Genetic diversity levels and population genetic structure were investigated through the genotyping of a collection of 295 date palm accessions ranging from Mauritania to Pakistan using a set of 18 simple sequence repeat (SSR) markers and a plastid minisatellite.Key Results Using a Bayesian clustering approach, the date palm genotypes can be structured into two different gene pools: the first, termed the Eastern pool, consists of accessions from Asia and Djibouti, whilst the second, termed the Western pool, consists of accessions from Africa. These results confirm the existence of two ancient gene pools that have contributed to the current date palm diversity. The presence of admixed genotypes is also noted, which points at gene flows between eastern and western origins, mostly from east to west, following a human-mediated diffusion of the species.Conclusions This study assesses the distribution and level of genetic diversity of accessible date palm resources, provides new insights on the geographic origins and genetic history of the cultivated component of this species, and confirms the existence of at least two domestication origins. Furthermore, the strong genetic structure clearly established here is a prerequisite for any breeding programme exploiting the effective polymorphism related to each gene pool.

The date palm - one of the oldest domesticated fruit crops - is the tree most adapted to growing in desert areas. It has always been looked upon as a key source of stability, survival and evolution of the oasis agro-system as it constitutes the basic features of the ecological pyramid in desert regions. Tunisian date palm germplasm is characterised by high genetic diversity, with more than 250 varieties identified. However, this patrimony is seriously menaced by severe genetic erosion due to different biotic and abiotic factors. In Tunisia, as well as in North African countries, dates are cultivated for fruit production, and all parts of the tree are used for many other artisanal and/or industrial purposes. Recent efforts have focussed on the development of phenotypic, biochemical and DNA-based markers useful in characterising the genetic diversity of date palm populations and to establish the relationships between different cultivars. This chapter reviews current efforts made towards developing such selection markers for Tunisian date palm cultivars for use in breeding programmes.

Clonal plants of date palm (Poenix dactylifera L.) were regenerated from juvenile leaves on regimes consisting of the use of 2,4-D. Success depended on the concentrations of 2,4-D tested. The cultures produced adventitious shoot buds directly at the basal part of leaves as well as excessive calli. Somaclonal variation in plantlets which can be induced by 2,4-D during recurrent somatic embryogenesis were tested by random amplified polymorphic DNA (RAPD) profiles. Nine arbitrary 10- mer primers were used to amplify DNA from 180 plantlets. RAPD patterns of the plantlets were identical with the original plant mother, indicating that 2,4-D did not induce somaclonal variation that can be detected by the RAPD technique.