EFFECT OF BIOREGULATORS AND HERBICIDES ON CALCIUM AND PHOSPHORUS CONTENT OF FRUITS

The effects of bioregulators and herbicides on fruit Ca and P content are reviewed.
They are classified as direct and indirect effects.
The direct effects of bioregulators (TIBA, daminozide, and paclobutrazol) operate through decreasing the basipetal movement of auxin (IAA) which in turn decreases the acropetal movement of Ca.
As a result (mostly in apple), Ca content is reduced.
The indirect effects are associated with (1) a change in fruit size, (2) elimination of shoot-fruit competition for nutrients, (3) increase in root mass, and (4) elimination of mycorrhizae.
The first three indirect effects potentially increase fruit Ca content, as may be seen from daminozide or paclobutrazol treatment.
Herbicides that maintain a weed free orchard floor greatly reduce mycorrhizal infection of the root and decrease P uptake and P content of fruits.
The direct and indirect effects of growth regulators may act independently, and when their effects are combined, it is difficult to predict the overall effect in any given situation.

VI International Symposium on Growth Regulators in Fruit Production

M. Faust, Anita N. Miller

https://doi.org/10.17660/ActaHortic.1989.239.68