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Charles R. Clement and Joseph DeFrank

Pejibaye (Bactris gasipaes Kunth) is being evaluated in Hawaii for production of fresh heart-of-palm. Yields and offshoot (sucker) production were evaluated in response to woven black polypropylene mat (control), three legumes [Arachis pintoi Krap. & Greg., Cassia rotundifolia Pers., and Desmodium heterocarpon (L.) DC], and a grass (Chloris gayana Kunth) used as ground covers. D. heterocarpon and C. gayana formed closed canopies quickly and controlled weeds well, but required more frequent mowing. A. pintoi formed a closed canopy slowly and only controlled weeds after forming a thick canopy, but required less mowing. Cassia rotundifolia died out after flowering and setting seed. All vegetative ground covers delayed heart-of-palm harvest and had reduced yields 1.5 years after planting. A combination of polypropylene (adjacent to plants) and vegetative ground covers (in service rows) may provide the best solution to minimizing labor for vegetative management in this orchard crop.

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Charles R. Clement and Joseph DeFrank

Pejibaye (Bactris gasipaes Kunth) is being evaluated in Hawaii for production of fresh heart-of-palm. Yields and offshoot (sucker) production were evaluated in response to woven black polypropylene mat (control), three legumes [Arachis pintoi Krap. & Greg., Cassia rotundifolia Pers., and Desmodium heterocarpon (L.) DC], and a grass (Chloris gayana Kunth) used as ground covers. D. heterocarpon and C. gayana formed closed canopies quickly and controlled weeds well, but required more frequent mowing. A. pintoi formed a closed canopy slowly and only controlled weeds after forming a thick canopy, but required less mowing. Cassia rotundifolia died out after flowering and setting seed. All vegetative ground covers delayed heart-of-palm harvest and had reduced yields 1.5 years after planting. A combination of polypropylene (adjacent to plants) and vegetative ground covers (in service rows) may provide the best solution to minimizing labor for vegetative management in this orchard crop.

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Mohamed A. Shaheen

Seeds of four Saudi date palm cultivars were germinated on a modified White's medium (liquid and solid) containing various concentrations of sodium, calcium, and magnesium chlorides. These salts were incorporated in the medium to simulate their concentrations in Saudi underground water commonly used for irrigation. Different germination responses were observed on the liquid and solid medium. Variations between the four test cultivars on the same medium also were noticed.

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Vyacheslav Gurevich, Uri Lavi and Yuval Cohen

Date palm (Phoenix dactylifera L.) is a major tree crop in arid regions of the Middle East and North Africa, having an important impact on the economy of many countries in these regions. Date palms are traditionally propagated through offshoots. The development of propagation methods through tissue culture resulted in massive expansion of date palm plantations. While most trees generated from tissue culture are normal and true-to-type, several typical abnormal phenotypes are detected. The present study applies amplification fragment length polymorphism (AFLP) analysis to characterize the genetic variation of two elite date cultivars, `Barhee' and `Medjool', as well as male clones, propagated from offshoots and through tissue culture. The two cultivars have very distinct AFLP band patterns. Most offshoots, as well as the tissue culture-propagated plants, have very similar band patterns, demonstrating a low level of genetic variation. However, a significant level of genetic variation was detected among `Medjool' plants generated from tissue culture. Several phenotypically abnormal trees were characterized by unique and different AFLP band patterns. The male clones are characterized by a high level of polymorphic bands. Genetic variation was also detected between various tissues of variegated `Medjool' trees propagated from tissue culture. The significance of these results, regarding the mechanism of the phenomenon and its relevance to agricultural practice, is discussed.

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Severn C. Doughty, Daniel J. Gill and David C. Blouin

Landscape palms were surveyed for cold damage 8 to 10 months after the coldest weather episode recorded this century in the New Orleans, La., area. Fourteen genera and 21 species of palms totaling 9039 individuals were surveyed and assigned to one of three condition categories within six geographic areas. Area 1, north of Lake Pontchartrain, was not a reliable area for the majority of the 21 species found. South of Lake Pontchartrain, areas 2-6 were considered statistically better for overall palm survival, with area 3 best followed by areas 4, 2, 5, and 6. Although species survival depended somewhat on area, 10 species were found to be statistically reliable south of Lake Pontchartrain: Brahea armata, Chamaedorea microspadix, Phoenix canariensis, Rhapidophyllum hystrix, Sabal mexicana, S. minor, S. palmetto, Sabal spp., Sabal spp. seedlings, and Trachycarpus fortune;. Two species, Phoenix reclinata and Phoenix spp., were found to be marginal and seven species were found to be unreliable: Butia capitata, Chamaerops humilis, Livistona chinensis, Rhapis excelsa, Syagrus romanzoffiana, Washingtonia filifera, and W. robusta. Due to low individual numbers, survival for three species could not be reliably estimated: Arenga engleri, Phoenix dactyfifera, and Serenoa repens.

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Shatha Matar Al-Matar, Mostafa M. Abo El-Nil, Jameel Al-Khairy and Gerald Klingaman

Cell suspension cultures of four date palm cultivars were established, namely, Niboat Saif, Madjhool, Sukarri, and Berhi. In this study, two factors were tested for their effect on embryo maturation and hyperhydration. The effect of sucrose concentration was assessed by inoculating 0.5 g of embryogenic callus into a liquid MS basal medium supplemented with 10 mg/L inositol, 3 mg/L glycine, 20 mg/L glutamine, and 0, 20, 30, 40, 50 g/L sucrose. Polyethylene glycol (PEG) concentration effect on embryo maturation and hyperhydration was tested. PEG (molecular weight 7000–9000) was added at concentrations of 0, 10, 30, and 60 g/L to the date palm suspension cultures. Cultures were examined and subcultured every 3 weeks for 2 months. Embryos formed were then transferred to a solid MS medium supplemented with 10 mg/L inositol, 3 mg/L glycine, 5 mg/L glutamine, and 30 g/L sucrose. The number of embryos germinated from each treatment was counted to compare cultivar differences. Preliminary data suggests that the medium containing 30 g/L sucrose is most effective for embryo maturation, and those embryos germinated when transferred to a solidified MS medium. The study found that incorporating PEG into the medium reduced the hyperhydration of date palm tissues. The various cultivars reacted differently to the treatments employed.

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Hameed J. Aljuburi

An experiment was conducted at the United Arab Emirates Univ., in Al-Ain, to study the effect of saline water on the growth characteristics of date palm (Phoenix dactylifera L.) seedings cultivar Lulu-salt alone or a combination of NaCl and indole acetic acid (IAA) or IAA alone were tested with different levels. Then the plant growth characteristics were measured. Hormone did not antagonize the salt effect on shoot length of date palm seedlings. Application of 24 mg·L–1 salt alone or in combination with hormone and 12 mg·L–1 in combination with 0.2 mg·L–1 IAA significantly increased the root: shoot ratio over the control. Irrigation date palm seedlings with saline water alone or in combination with IAA for 80 days resulted in a significant increase in dry matter (percentage) of leaves with salt symptoms, whereas the number of leaves per seedling were reduced over the control. The results also showed that the irrigation of seedlings with 0.15 mg·L–1 IAA in combination with 24 or 12 mg·L–1 salt alleviated adverse effect of salt by increasing or reducing significantly root length or leaves with salt symptoms percentage over using 24 or 12 mg·L–1 salt alone.

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Timothy K. Broschat and Monica L. Elliott

Foxtail palms (Wodyetia bifurcata Irvine) were grown in 6.2-L containers using a 3 calcitic limestone gravel: 2 coir dust (by volume) substrate to induce Fe chlorosis. Plants were treated initially and 2 and 4 months later with soil applications of FeDTPA, FeEDDHA, FeEDTA+FeHEDTA on vermiculite, FeEDTA+FeDTPA on clay, ferric citrate, ferrous ammonium sulfate, ferrous sulfate, ferrous sulfate+sulfur, or iron glucoheptonate at a rate of 0.2 g Fe/container. Similar plants were treated initially and 2 and 4 months later with foliar sprays of FeDTPA, FeEDDHA, ferric citrate, ferrous sulfate, or iron glucoheptonate at a rate of 0.8 g Fe/L. After 6 months, palms receiving soil applications of FeEDDHA, FeEDTA+FeHEDTA on vermiculite, FeDTPA, or FeEDTA+FeDTPA on clay had significantly less chlorosis than plants receiving other soil-applied Fe fertilizers or untreated control plants. Palms treated with foliar Fe fertilizers had chlorosis ratings similar to untreated control plants. Palms with the most severe Fe chlorosis also had the highest levels of leaf spot disease caused by Exserohilum rostratum (Drechs.) K.J. Leonard & E.G. Suggs. Neither chlorosis severity nor leaf spot severity was correlated with total leaf Fe concentration.

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Alan W. Meerow and Timothy K. Broschat

Anatomical differences in leaves of queen palm [Syagrus romanzoffiana (Chamisso) Glassman] showing visible K, Mn, and Fe deficiency symptoms are described. Potassium-deficient leaves showed less organization in the mesophyll than healthy leaves. Adaxial fibers increased in diameter. Chloroplast frequency was reduced overall, but most severely in areas of the leaf showing gross symptoms of the deficiency. Manganese-deficient leaves had reduced chloroplast frequency, especially in tissue near necrotic areas, and thicker and more fibers per unit length. Iron-deficient leaves had few chloroplasts throughout the mesophyll, and also thicker and more fibers per unit length.

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Timothy K. Broschat

All leaves from 10 replicate Cocos nucifera L. `Malayan Dwarf' (COC) and Phoenix canariensis Chabaud (CID) trees were sampled for leaf nutrient analysis. In addition, the leaflets of the youngest fully expanded leaves and the third oldest leaves were divided into five groups along the primary leaf axis and these leaflets were then cut into thirds to determine nutrient distribution patterns within leaves and leaflets. Nutrient remobilization rates were calculated for N, P, K, Mg, and Mn. Results showed that N, P, and K were highly mobile within and between leaves of both species of palms. Up to 31% of the N, 66% of the K, and 37% of the total P in the oldest leaves were ultimately remobilized to newer leaves within the palm. Magnesium remobilization rates averaged ≈71% for CID but only ≈10% for COC. The middle-aged leaves appeared to be the primary sink for Mg in COC, rather than the youngest leaves as in CID. Manganese was also quite mobile in both species, with up to 44% of the total Mn remobilized in CID. Samples consisting of recently matured leaves were determined to be the most appropriate for Ca, Fe, Mg (COC only), and Zn, but oldest leaves are more suitable for N, P, K, and Mn analysis.