Gibberellic acid
I first read of the use of gibberellic acid or A3 in the Royal National Rose society Rose Annual 1978. The article I read the author discribed the use of gibberellic acid as a seed stratification aid. A three-year experiment showed an increased in the germination rate of rose seeds soaked in Gibberellic acid by about three times the rate as untreated seeds.
Gibberellic acid (actually a group of related substances called gibberellins) was discovered as a metabolic byproduct of the fungus Gibberella fujikuroi, which causes the stems of growing rice to elongate so rapidly the plant collapsed. Synthetic forms of gibberellic acid are available commercially.
Gibberellic Acid (GA) is a very potent hormone whose natural occurrence in plants controls their development. Since GA regulates growth, applications of very low concentrations can have a profound effect. Timing is critical: too much GA may have an opposite effect from that desired; too little may require the plant to be repeatedly treated to sustain desired levels of GA.
By doing a little research I found you get the following benefits by using Gibberellic Acid
- Overcoming dormancy. Treatment with high concentrations of GA is effective in overcoming dormancy and causing rapid germination of seed. Concentrations of about 2 ppm can cause tubers to sprout earlier.
- Premature flowering. If a plant is sufficiently developed, premature flowering may be induced by direct application of GA to young plants. This action is not sustained and treatment may have to be repeated. Formation of male flowers is generally promoted by concentrations of 10 to 200 ppm, female flowers by concentrations of 200 to 300 ppm. Concentrations of more than 600 ppm markedly suppress initiation of both male and female flowers.
- Increased fruit set. When there is difficulty with fruit set because of incomplete pollination, GA may be effectively used to increase fruit set. The resulting fruit maybe partially or entirely seedless. GA has increased the total yield in greenhouse tomato crops both as a result of increased fruit set and more rapid growth of the fruit.
- Hybridizing. Pollination within self-incompatible clones and between closely related species may some times be forced by the application of GA and cytokinin to the blooms at the time of hand pollination.
- Increased growth. GA applied near the terminal bud of trees may increase the rate of growth by stimulating more or less constant growth during the season. In a Department of Agriculture experiment, the GA was applied as a 1-% paste in a band around the terminal bud of trees. Treatment was repeated three times during the summer. Walnut tee growth was 8.5 ft. for treated trees, 1.5 ft. for untreated trees.
- Frost protection. Spraying fruit trees at full-blossom or when the blossoms begin to wither can offset the detrimental effects of frost.
- Root formation. GA inhibits the formation of roots in cuttings.
I took this information and decided I could put it to work with my rose hybridizing. In using Gibberellic acid I have much bigger and healthy rose bushes. I have increased bloom size and number; I no longer have shy bloomers. My bushes set more hips. I now have repeat blooming on non repeat blooming roses. My seedlings mature as much in one year now as they used to in two or three years. The company I buy my Gibberellic acid from is the MegaGro Co. I found the product easy to use and very reasonably priced. If you give the following reference code (
JR101) they will give you a 10 % discount!
Repeat blooming seedling
I use MegaGro first as soon as my seedlings sprout. I spray each seedling once.
I spray repeat flowering seedlings again as soon as they flower for the first time and the bloom color can be seen.
At time of transplant I put the seedling in the ground, water them, spray them with MegaGro and then place a milk jug around it. I remove the milk jug in two or three days. I then repeat the MegaGro treatment every time it flowers for the first two or three years.
Non-Repeat blooming seedling
I use it first as soon as my seedlings sprout. I spray each seedling once.
I spray non-repeat flowering seedlings again as soon as they develop three or four true leaves.
At time of transplant I put the seedling in the ground, water it, spray it with MegaGro and then place a milk jug around it. I remove the milk jug in two or three days. I then repeat the MegaGro treatment every month or so for the first two or three years.
Repeat blooming rose bushes
In early spring after danger of frost has passed I spray the canes with MegaGro to help break dormancy and to develop a strong thick frame or infrastructure. This some times will delay first flowering but believe me you will be compensated throughout the rest of the growing season. I then spray flower buds and foilage approximately monthly when buds are just showing color.
Non-Repeat blooming rose bushes
In early spring after danger of frost has passed I spray the canes to help break dormancy and to force all bud-wood to sprout. I then stop the MegaGro till flower buds show color. I spray buds once then start spraying the bush monthly after all blooming is finished to develop the following years bud-wood.
