The Influence of the Physical State of the Nutrient Media on the Growth of Excised Date Palm (Phoenix dactylifera L.) Roots

Abstract

The effects of the physical state of nutrient media on the growth and elongation of excised date palm roots were investigated. Roots were cultured in a nutrient medium containing MS salts mixture, 1/2 modified White's organics, and (in mg–liter–1): NaH2PO4–H2O, 170; sucrose, 60,000; inositol, 40; adenine sulfate, 240; activated charcoal, 4000; 2,4-D, 1; kinetin, 2. pH was adjusted at 5.7 ± 0.1. Both agar and Gelrite were singly used as solidifying agents. Liquid media were either stationary or rotated on gyratory shakers at 70 to 80 rpm. The effects of incubation of cultured roots under light or dark conditions were also studied. Media pH and its effects on growth and elongation of cultured roots were tested at various ranges (3, 4, 5, 6, 7, 8, 9, 10). Trials were also made to determine the passage length for transfer and subculture of cultured roots to a newly prepared medium. Liquid media highly supported better growth and elongation of cultured roots compared to solidified media. There was no significant difference in growth or elongation between agar or Gelrite media. Shaking liquid medium resulted in significantly better growth and elongation compared to stationary medium. No difference was observed between dark- and light-incubated cultured roots. Cultured roots grew and elongated better at pH 7.0–8.0. No growth or elongation occurred at pH 9.0. Roots continued to grow and elongate even after 12 weeks in culture. Therefore, 10 to 12 weeks after culture was determined to be the optimum passage length for date palm root culture.