MINOR CONTAMINANTS OF BIURET AND CYANURIC ACID AS ADDITIVES FOR PEACH FRUIT THINNING WITH UREA

The precise fruit thinning responses of peach cultivars to urea is variable and sometime unpredictable.
Biuret and cyanuric acid (CA) are phytotoxic minor contaminants found in synthetic urea.
It was assumed that these compounds had a direct effect on fruit thinning.
The objective of the present study was to evaluate the contribution of biuret and CA to the fruit thinning effect of urea.
Experiments were carried out to evaluate the effect of urea and it’s contaminants, alone and in combination, on fruit thinning.
Neither biuret nor CA alone influenced significantly the eventual fruit set.
A concentration of 160 ppm of biuret in 8% urea solution caused some synergistic effect which was not increased further by addition of higher amounts of biuret.
No synergistic effect was found when biuret was applied in combination with 4% and 12% urea.
Urea from several sources containing different levels of biuret had similar thinning effect.
When CA was applied in combination with urea, synergistic effect was evident close to application.
With time, this effect on abscission disappeared as the natural abscission of the control reached the level caused by urea + CA. It was concluded that these contaminants in urea solutions do not contribute significantly to the thinning effect of urea.

VII International Symposium on Plant Growth Regulators in Fruit Production

S. Zilkah, I. Klein, I. David

https://doi.org/10.17660/ActaHortic.1993.329.51