Articles
Alternative rest breaking agents and vigour enhancers tested on Fuji apple shoots under mild conditions
Article number
1346_19
Pages
145 – 152
Language
English
Abstract
The use of rest breaking agents is essential for successful bud break of apples in areas with insufficient winter chill.
Hydrogen cyanamide (Dormex®) and mineral oil are currently the industry standard for rest breaking in apples produced in South Africa.
As cyanamide is under scrutiny for its hazardous effects on man and environment, the need for alternative compounds increases.
This study investigates the potential rest breaking capabilities of nitric oxide (produced chemically and enzymatically), in the presence of oil, as a safer, more environmentally friendly alternative to Dormex®. The use of growth enhancing compounds (hormones and N-containing) to restore the vigour of apple shoots effected by insufficient winter chill is also included.
One-year-old Fuji apple shoots from a mild winter area were treated with a selection of growth enhancing and potential NO producing compounds and exposed to development forcing conditions (12°C/20°C, night/day cycle). Onset, rate and percentage bud break were used as indications of rest breaking potential.
Over the two seasons (2015 and 2016), the growth measurements of all the growth-enhancing compounds tested equal to Dormex® and oil.
Promalin® and Maxcell® showed some potential, as they were consistently the top performers.
No conclusive evidence was found for improved bud break using the growth enhancers.
Some of the NO producing rest-breaking alternatives had bud break percentages equal to or higher than that of Dormex® and oil but showed a prolonged onset to budburst and an extended time period to completion.
KNO3 was the most promising compound with positive results at the lowest concentration tested and NaNO2 the least effective with some contradicting results and lethal activity higher than 1M. In conclusion, it was found that NO producing compounds acted as a rest breaking agent in apple buds with its potential equal to that of Dormex® and oil but is slow acting.
Hydrogen cyanamide (Dormex®) and mineral oil are currently the industry standard for rest breaking in apples produced in South Africa.
As cyanamide is under scrutiny for its hazardous effects on man and environment, the need for alternative compounds increases.
This study investigates the potential rest breaking capabilities of nitric oxide (produced chemically and enzymatically), in the presence of oil, as a safer, more environmentally friendly alternative to Dormex®. The use of growth enhancing compounds (hormones and N-containing) to restore the vigour of apple shoots effected by insufficient winter chill is also included.
One-year-old Fuji apple shoots from a mild winter area were treated with a selection of growth enhancing and potential NO producing compounds and exposed to development forcing conditions (12°C/20°C, night/day cycle). Onset, rate and percentage bud break were used as indications of rest breaking potential.
Over the two seasons (2015 and 2016), the growth measurements of all the growth-enhancing compounds tested equal to Dormex® and oil.
Promalin® and Maxcell® showed some potential, as they were consistently the top performers.
No conclusive evidence was found for improved bud break using the growth enhancers.
Some of the NO producing rest-breaking alternatives had bud break percentages equal to or higher than that of Dormex® and oil but showed a prolonged onset to budburst and an extended time period to completion.
KNO3 was the most promising compound with positive results at the lowest concentration tested and NaNO2 the least effective with some contradicting results and lethal activity higher than 1M. In conclusion, it was found that NO producing compounds acted as a rest breaking agent in apple buds with its potential equal to that of Dormex® and oil but is slow acting.
Publication
Authors
L. Allderman, W.J. Steyn, E.D. Louw
Keywords
alternative rest breaking, nitric oxide, mild winters
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