RESPONSES TO ENDOGENOUS AND APPLIED GROWTH REGULATORS DURING THE PROPAGATION AND RAISING OF FRUIT TREES

B.H. Howard, Nina L. Bassuk, Y. Kim
The main results are given from five studies examining the role of exogenous and endogenous growth regulators at different stages in the propagation and nursery production of fruit trees.
  1. A major component of the response to dipping plum winter cuttings to different depths in 50% ethanol or acetone solutions of IBA is increased uptake resulting from absorption through the cut end of liquid draining from the epidermis. Pretreatment of the cutting base with an organic solvent increased the rooting response to powder formulations.
  2. A phenolic rooting cofactor obtained from vacuum-extracted apple sap has root-promoting activity synergistic with IBA. It appears to be a product of a reaction between polyphenol oxidase and phloridzin and to be the cause of seasonal changes in rooting potential of winter cuttings.
  3. The growth of dwarf plum micropropagules and summer cuttings was promoted by sprays of GA3. These substitute for chilling requirement after plants have been checked following potting.
  4. Removal of small, unsaleable shoots in layer/stoolbeds of MM.106 apple by early-summer sprays of 4% Tipoff (NAA) resulted in the remaining shoots giving a higher proportion of top-grade rootstocks suitable for high budding as long as soil fertility was adequate.
  5. Higher lateral branches on maiden trees raised from a single scion bud were obtained by delaying the removal of rootstock shoots, apparently because this increases levels of ABA which inhibits the emergence of lower laterals. This simulates the response in grafted trees where up to 4 scion shoots begin to grow before one is selected to be the maiden tree.
Howard, B.H., Bassuk, Nina L. and Kim, Y. (1981). RESPONSES TO ENDOGENOUS AND APPLIED GROWTH REGULATORS DURING THE PROPAGATION AND RAISING OF FRUIT TREES. Acta Hortic. 120, 199-210
DOI: 10.17660/ActaHortic.1981.120.27
https://doi.org/10.17660/ActaHortic.1981.120.27

Acta Horticulturae