Occurrence and histological structure of offshoots and inflorescences produced from Phoenix dactylifera L. plantlets in vitrol

TISSEKATB,. AND D. A. DEMASON(U SDA, Ag. Res. Service, Western Region, Fruit and Veg. Chem. Lab., Pasadena, CA 91 106 and Dept. Botany and Plant Sciences, Univ. California, Riverside, CA 92521). Occurrence and histological structure of offshoots and inflorescences produced from Phoenix dactylifera L. plantlets in uitro. Bull. Torrey Bot. Club 112: 35-42. 1985.-A histological investigation into the origin of offshoots and inflorescences produced from Phoenix dactylifera L., date palm, plantlets derived from lateral bud callus, excised zygotic embryos, and shoot tip cultures was conducted. Plantlets, about 2-4 months of age, could exhibit offshoot production when grown on a basal nutrient media supplemented with 0.1 mgll a-naphthaleneacetic acid (NAA). Histological examination revealed that these additional shoots were derived from a common shoot axis via lateral bud proliferations. Suckering occurred in about 40 per cent of the asexual plantlets derived from callus; suckering was observed from plantlets derived from excised embryos and shoot tips somewhat less frequently (10 per cent and 20 per cent, respectively). Inflorescences were sometimes produced from these lateral bud outgrowths in cultured shoot tip and excised embryo cultures. Inflorescence production occurred on nutrient media containing 0.1 mgll NAA and 5-15 mgll benzyl adenine, kinetin, or N6-(A2-isopentyl)adenine. Tissue culture conditions were found to be suitable for development of mature shoot phenomena from palm plantlets. Usually such a shooting state only occurs when a palm is in its fourth through seventh year of development. Initiation and production of these lateral bud outgrowths in a controlled system can be useful to study the physiological control of palm growth which, heretofore, has been difficult to study.