Promotive effects of a 5-aminolevulinic acid-based fertilizer on growth of tissue culture-derived date palm plants (Phoenix dactylifera L.) during acclimatization

The low survival rate together with the slow growth rate of the survived tissue culture-derived date palm plants during acclimatization are critical problems facing the tissue culture as a commercial technique of date palm propagation. Growth parameters, pigment contents and nutrient uptake were examined in tissue culture-derived date palm plants (Phoenix dactylifera L.) c.v. ‘Khalas’ subject to different concentration of a 5-aminolevulinic acid-based fertilizer, commercially known as Pentakeep-v, during acclimatization. Pentakeep application at 0.02, 0.04 or 0.08% at 10 days interval significantly enhanced growth at both VP2- and VP3-stage of acclimatization. However, such effects were not detectable at the VP1-stage. At the end of this stage, the successful plants ranged from 66.6 to 78.3% with no significant differences between the Pentakeep treatments and the control. All successful plants at this stage survived both the VP2 and the VP3 stages of acclimatization. Plants treated with Pentakeep, especially at 0.04 and 0.08%, developed faster and were ready for transplanting to the nursery or to the open field conditions about 4–5 months earlier than the control or those treated with 0.02% Pentakeep. Pentakeep significantly increased chlorophyll a contents in all treatments which was subsequently reflected on total chlorophyll and chlorophyll a/chlorophyll b ratio. Pentakeep application, especially at the 0.08%, significantly increased the concentration of N, Cu and Zn in the leaves of treated plants. The concentration of available P and Zn in the soil was significantly higher in the Pentakeep treatments than the control.