Date of Award
Department of Horticulture
Master of Science
Louis T. Kardos
Albert F. Yeager
Five different phosphorus slats were applied to the foliage of Malus robusta trees growing in the greenhouse. The radioactive isotope of phosphorus (P32) was used as a tracer in studying the absorption and translocation of the foliarly applied phosphorus.
Observations were made on the translocation of phosphorus by taking radioactive counts on fifteen-sixteenths inch leave discs at weekly intervals. At the end of the experiment, samples from the old and new leaves and stems and from the roots were analyzed and counted to determine the total P2O5 in the sample. The percent P2O5 which cam from foliar application was determined from the radioactive counts per minute obtained from the samples.
The results show conclusively that water soluble phosphorus applied as a foliar spray to foliage and small branches of apple trees can be absorbed and translocated to other parts of the trees. Under conditions of this experiment di-ammonium phosphate was absorbed and translocated in larger amounts than any of the other phosphorus salts used.
The phosphorus applied as a foliar spray was absorbed and translocated to the roots in more than double the quantity that was translocated to foliage in the unsprayed area on the same tree. Translocation of phosphorus was greater to young leaves in the unsprayed area than to older leaves in the same area.
Smith, R. Dee, "Absorption of Phosphorus by Foliage of Malus Robusta" (1952). Master's Theses and Capstones. 1498.