HISTORY OF DATE PALMS Date palm ( Phoenix dactylifera L.) has long been one of the most important fruit crops in the arid regions of the Arabian Peninsula, North Africa, and the Middle East. During the past three centuries, dates were also
The seeds of two cultivars of Phoenix dactylifera L. (Medjol and Deglet-Nour) were cultured on modified Murashige and Skoog (MS) medium containing 0.5 mg/l NAA and 2.0 mg/l BA. Later they were treated with 25 or 50 pulses of excimer laser radiation. The results indicate that these seeds exhibited significantly less contamination than control. The highest percentage germination for both cultivars was obtained with explants treated with 50 pulses excimer laser radiation. Compared to other treatments, the occurrence of somatic embryo-genesis and shoot regeneration was greater with the Medjol cultivar.
Date palm ( Phoenix dactylifera L.) is one of the most successful fruiting trees in semiarid and arid areas around the world, and it is regarded as a significant subsistence crop ( Mohamed et al., 2014 ). Date is the most popular fruit consumed
Currently, the identification and characterization of date palm varieties rely on a small number of morphological traits, mainly of fruit, which are complex and greatly influenced by the environment. As a result, different varietal names may actually refer to the same variety while different varieties may have the same name. Therefore, new descriptors like molecular markers are required to identify, characterize, and estimate genetic diversity in this crop. Here we used amplified fragment length polymorphism (AFLP) markers to discriminate 18 Iraqi date palm varieties and to estimate the genetic relationship among the varieties. A total of 122 polymorphic AFLP loci were scored, with an average of 17.4 polymorphic loci per primer combination. The use of any one of the four combinations, P101(aacg)/M95(aaaa), P74(ggt)/M95(aaaa), P73(ggg)/M95(aaaa), or P100(aacc)/M95(aaaa), was sufficient to uniquely identify all the varieties. Jaccard's genetic similarity index ranged from 0.108 to 0.756, indicating moderate to diverse relationships. Estimation of average proportion of fixed recessive AFLP loci indicated that most of the loci in variety `Chipchab' were fixed, whereas most of the loci in `Jamal Al-Dean' could be heterozygous and in-between in other varieties. Unweighted pair group method with arithmatic mean (UPGMA) analysis ordered the date palm varieties first into two broad groups at 27% similarity levels. One group consisted of seven varieties and the second group consisted of the remaining 11 varieties of date palm. These results showed that the AFLP technique is an efficient method for varietal identification and estimating genetic relationships in date palm.
The study was carried out at the Experimental Station of Agric. Sci. College at Al-oha region. Eight hundred seedlings (7 months old) were chosen for each following cultivars, Lulu, Boman, Barhee and Khalas. The seedings for each cultivars were irrigated weekly with 0, 6, 12, 18 g I.-1 Nacl solution.
The results revealed fresh weight of stems, roots and number of leaves/plant of Lulul, Barhee and Khalas cultivars progressively reduced with increasing Nacl concentration in irrigation water, while dry matter percentage of stems and roots increased and increasing salinity in irrigation water. The results also declared that the seedlings of four date palm cultivars has similar behavior, when exposed to high Nacl concentration in irrigation water during long term.
Date palm trees are among the most plentiful fruit trees in the Arabian Gulf States. Bioregulators have been used for the improvement of quality and productivity of date plam tree fruits. Application of gibberellic acid (GA3), naphthalene acetic acid (NAA), and ethephon, separately or in a mixture, has significant effects on fruit set, fruit dry matter percentage, fruit soluble percentage, fruit ripening, and yield of date palm trees. A study was conducted to assess relative effectiveness of GA3, NAA, ethephon, and a mixture of growth regulators on some fruit characteristics, and productivity of `Barhee' date plam trees. Five uniform female `Barhee' date palm trees were pollinated on 5–15 Mar. 1994, 1995, and 1996 by placing eight fresh male strands on female spadix centers (flower cluster). Ten flower clusters were used on each tree, and every two flower clusters were subjected to one of the following treatments: control (water), 150 mg·L–1 GA3, 100 mg·L–1 NAA, 1000 mg·L–1 ethephon, and a mixture of growth regulators. The fruit set (%), dry matter (%), total soluble solids (°Brix), fruit ripening (%), and fruit weight (kg per bunch and per tree) were measured. The data showed that the application of GA3 or ethephon on flower clusters of `Barhee' date palm trees had no constant effect on fruit characteristics and productivity of trees. NAA or a mixture of growth regulators reduced fruit dry matter percentage, fruit ripening percentage, and increased fruit weight per bunch and per tree. Spraying `Barhee' date palm flower clusters with NAA or a mixture of growth regulators 20 days after pollination decreased dry matter percentage, fruit ripening, and increased fruit flesh percentage and tree yield.
Several experiments were conducted in this investigation with the objective of determining the chemical components and the physical state of an optimal medium for the growth and elongation of excised date palm, cv Sukkari, roots. The chemical tests carried out included: Comparison of (MS)-salts with “White's”-salts mixture and different concentrations of (MS)-salts and its chelated iron; sugars; Modified White's Organics; inositol; adenine sulfate; growth regulators; and some antioxidants. The physical tests, on the other hand, included comparison of the growth and elongation of cultured roots in a liquid or on solidified nutrient media. The effects of various pH values were also tested. Roots were cultured in basal nutrient media composed of: (MS)-salts mixture, and (in mg·liter–1): NaH2PO4·H2O, 170; sucrose, 30,000; inositol, 200; Modified White's Organics; adenine sulfate, 120; activated charcoal, 1500; (2,4-D), 1; kinetin, 2. pH was adjusted at 5.7 ± 01. (MS)-salts mixture was found to be superior to “White's”-salts. No significant difference was observed between (1/2MS) and full-strength (MS)-salts. However, twice the concentration was found to be inhibitory. The normal concentration of (MS)-Fe was found to be optimum for root growth and elongation. The optimal concentration most suitable for the growth and elongation of excised date palm roots has been determined for each of: sugars; Modified White's Organics; inositol; and adenine sulfate. The only growth regulator that needs to be added to the nutrient medium is 2,4-D at 0.1–1.0 mg·liter–1. The study showed the importance of the inclusion of activated charcoal to the nutrient medium. The growth and elongation of roots were both stimulated at all concentrations tested. (PVP), on the other hand, was inhibitory at all concentrations tested. Shaken liquid media was recommended for better root growth and elongation at pH 7.0–8.0. Incidentally, the medium developed was found to support the growth and elongation of roots excised from two other cultivars, namely `Khudri' and `Khaias'.
This experiment was conducted to study the effects of bagging on fruit set, fruit characteristics and yield of Khastawi Date Palm CV. Two different types of bags were used: cloth and paper. The spadices were covered immediately at two different times during the first season; one month and the second continued until harvest time. Since positive results were obtained during the season, two extra bagging treatments were added in the second season (2 and 3 months). Unbagged spadices were used as control for both seasons. The results indicated that there were no significant differences between the two types of bags. Moreover, bagging for either two or three months produced positive results in fruit set improvement and yield.
Six date varieties from Egypt, one `Deglet Noor' and four `Medjool' date accessions from California, and 66 accessions of `Medjool' date from Morocco, the country of origin of `Medjool' date, were examined using four sets of fluorescent labeled amplified fragment length polymorphism (AFLP) markers. A total of 402 AFLP bands were generated and 160 were polymorphic (39.8%). The 66 `Medjool' accessions from Morocco shared minimum 79% of genetic similarity. These results support the hypothesis that `Medjool' date is a landrace variety and not a genetically uniform variety. `Medjool' is the first confirmed landrace variety of date palm worldwide. This raises the possibility that other landrace varieties of date palm may exist in different date-growing areas and in centers of diversity. The confirmation of a landrace variety of date palm also has significant impact on future date palm germplasm collection and preservation. The mechanism(s) creating the genetic variation within `Medjool' accessions remains unknown. One possible mechanism is that spontaneous genetic changes could occur frequently within vegetative tissues of date palm like offshoots under high temperature and drought stresses.
Abstract
Endogenous root promoting and root inhibiting activity as measured by the mung bean bioassay showed 2 rooting promoters at Rf 0.1-0.2 and at Rf 0.3-0.5, respectively. Extracts were paper chromatographed with isopropanol: water (8:2 v/v). No clear correlation was found between rooting ability and root promoting activity. Root inhibiting activity at Rf 0.5-0.8 was higher in difficult-to-root than in easy-to-root offshoots. The total carbohydrate content was higher in easy-to-root than in difficult-to-root offshoots although the latter contained more reducing sugar.