PLANT GROWTH REGULATOR ABSORPTION THROUGH ROOTS

The usual approach in applying exogenous plant growth regulators (PGRs) to fruit trees is through foliar sprays.
However, the retardant paclobutrazol enters the plant mainly through the roots.
A common way to target the roots is via a soil drench.
Conversely, apple rootstocks often have a mass of small roots on the rootstock trunk below the graft union.
These were targeted using a trunk soil-line pour (TSLP) of an aqueous solution containing known amounts of a PGR chemical.
This method and avenue of entry into the plant to produce a vegetative response were found to be highly effective for apple and peach trees.
In greenhouse experiments using the TSLP method on young tomato plants, several PGRs were found to be readily absorbed by roots, based on vegetative growth retardation or stimulation.
Thus, the roots can afford an effective avenue for PGR absorption by plants, and, for some PGR chemicals, an improvement over targeting the leaves, or as an effective method but with a lower quantity of chemical, for producing a favorable growth response.

V International Symposium on Growth Regulators in Fruit Production

L.D. Tukey

https://doi.org/10.17660/ActaHortic.1986.179.21