Ppm Gibberellic Acid Research Articles

Response of Phony-infected Peach Trees to Gibberellic Acid1

Abstract Peach trees (Prunus persica (L.) Batsch) dwarfed by phony disease responded to 2 summer applications of 264 ppm gibberellic acid (GA) by breaking the disease-induced rest period and resuming nearly normal twig growth. No twig growth was produced on untreated trees and no significant growth occurred on phony trees treated with combinations of cytokinins, sodium isoascorbate, calcium nitrate, urea, or citric acid.

SOME CLUSTER THINNING AND GIBBERELLIC ACID EFFECTS ON JUICE AND WINE QUALITY OF DE CHAUNAC GRAPES

Thinning to one and two flower clusters per fruitful shoot significantly increased total soluble solids and total phenols but had no effect on titratable acidity of de Chaunac grapes in two vineyards differing widely in vine vigor and soil type. Treatment with 50 ppm gibberellic acid 10 days after bloom did not affect juice quality at either location. Grapes from the high vigor, heavy soil site were particularly high in titratable acidity, and potassium content was higher in berries from thinned vines in the same vineyard. An early assessment of wine quality showed the one-cluster treatment to be superior.

SOME CLUSTER THINNING AND GIBBERELLIC ACID EFFECTS ON FRUIT SET, BERRY SIZE, VINE GROWTH AND YIELD OF DE CHAUNAC GRAPES

De Chaunac grapes were thinned to one- and two-flower clusters per fruitful shoot, cluster-pruned by removing part of the flower cluster of two clusters per shoot and/or sprayed with 50 ppm gibberellic acid (GA3) 10 days after bloom. A low to moderate vigor vineyard was treated in 1974 and a high vigor vineyard treated in 1975. GA3 enhanced berry weight in both trials, the greatest effect being on berries in more distal clusters. GA3 did not affect berry set. Thinning to one cluster reduced yield in both tests. Thinning to two clusters coupled with cluster pruning reduced yield in the high vigor block. Berry set was enhanced by thinning to one cluster in the vigorous block and by cluster pruning in both trials. Individual berry weight was increased by thinning in 1974 and by thinning plus GA3 in 1975. Thinning to one cluster coupled with GA3 treatment increased vine growth in both experiments.

On the Germination of Seeds of Comptonia peregrina, the Sweet Fern

Fruits of the sweet fern, Comptonia peregrina (L) Coult., possess a hard, resistant, sclerified pericarp which surrounds a membranous seed coat or testa which in turn encloses the embryo. Scarification of the fruit, low-temperature treatment of moistened fruits, and a variety of chemical treatments failed to elicit seed germination. Treatment of the whole fruit with 500 ppm gibberellic acid (GA3) for up to 24 h elicited 20% germination, which increased to as high as 80% when combined with scarification. Mechanical removal of the pericarp did not allow germination; removal of both pericarp and the seed coat membranes resulted in good germination Best germination was obtained with isolated embryos treated with 1-10 ppm GA3. The age of the fruit in storage had no effect on development of the isolated embryo but did affect the response of intact seeds to treatment with GA3. Fruits of Myrica gale L. and M. cerifera L. showed improved germination following GA3 treatment. An inhibitor in the seed coat of Comptonia, possibly abscisic acid, was believed to be responsible for fruit dormancy in this plant.

Effect of duration of after-ripening and gibberellic acid on germination of seeds and growth of seedlings of pecan in Egypt

The effect of stratification for 2–4 weeks and gibberellic acid (100 and 200 ppm) on germination of seeds and on total plant height was studied. The treatments resulted in earlier germination of seeds. The % germination was remarkably increased and stratification for 4 weeks followed by a 24-h soak in 100 ppm gibberellic acid solution gave the highest % germination. Total plant height was increased by the treatments and the effect was more profound when the seeds were stratified for 4 weeks followed by a 24-h soak in 200 ppm gibberellic acid solution.

Flowering of Azaleas with Controlled Photoperiods and Gibberellic Acid1

Abstract Plants of 4 azalea cultivars which remained in a greenhouse with 18°C minimum temperature from last pinch through flowering and received 18-hour photoperiods (LD) following 6, 8, or 10 weeks of 9-hour photoperiods (SD) flowered 2 to 7 weeks earlier than plants cold-stored at 3°C for 5 weeks following 12 weeks of SD. Flowering of cvs. Red Wing, Alaska, and Gloria was hastened more by LD treatment than by 5 weekly applications of 1000 ppm gibberellic acid (GA3), whereas flowering of ‘Chimes’ was affected about equally by these 2 factors. Flowering was most uniform with cold-storage, but plants of all cultivars except ‘Chimes’ were well covered with flowers following all treatments. Percentage of flowers open at one time increased as SD exposure increased from 6 to 10 weeks and that of ‘Chimes’ was increased by GA3 treatment. Vegetative bypassing varied more among cultivars than among treatments. Pedicels of ‘Alaska’ and ‘Chimes’ flowers on plants with LD treatment without GA3 were shorter than those on cold-treated plants, whereas those with LD plus GA3 were longer. Succinic acid-2, 2-dimethylhydrazide (SADH) at 3000 ppm delayed flowering of non-cold-treated plants of ‘Red Wing’, ‘Alaska’, and ‘Gloria’.

Heat-induced growth retardation and attempts at its prevention in barley and wheat coleoptiles

Intact barley coleoptiles subjected to high temperature stress of 46°C for up to 4 h showed a significant decrease in their growth rate, and in the final length attained by the coleoptiles before exsertion of the true leaves within. These effects of high temperature were progressively more pronounced with increase in duration of stress. Excised wheat coleoptile sections also experienced a similar growth retardation due to heat stress. This heat-induced growth retardation could not be prevented by exogenous applications of 0·5–100 ppm indole-3-acetic acid or 0·5–5 ppm gibberellic acid; nor by dilute aqueous solutions of calcium chloride, cobalt nitrate or zinc sulphate. The agronomic significance of heat-induced coleoptile stunting is briefly discussed.

Gibberellic Acid, Seed Number and Rate of Maturation as Related to Uneven-Ripening ‘Concord’ Grapes1

Abstract Uneven-ripening ‘Concord’ grapes were treated with 250 ppm gibberellic acid (GA3) about 2 weeks prior to harvest. “Green” berries responded with increased rate of ripening over untreated “green” berries as measured by soluble solids and anthocyanin content. GA3-treated berries also developed a callus-like layer between the pedicel and the skin which delayed drop also resulting in more evenly ripened clusters. In uneven-ripening clusters, “green” in contrast to “colored” berries had significantly fewer seeds and many of these seeds had aborted.

The in vitro growth and metabolism of Acer saccharum tissue

Isolated sugar maple callus was grown on defined medium containing 0.2 kinetin and 2.0 ppm indoleacetic acid. Selected components of the basal medium were varied but did not result in increased tissue growth. The presence of 1, 5, or 25 ppm gibberellic acid in the culture medium did not increase the secretion of starch digesting materials by the tissue. The diameter of the starch digestion zone was not influenced by changing the acidity of the medium in the range of pH which supported tissue growth. The ability of isolated callus tissues from various species to digest extracellular starch was examined. It was found that equal amounts of various tissues do not possess an equal capacity for the in vitro secretion of extracellular materials, most probably enzymes, into the culture medium. It was found that isolated sugar maple tissue metabolized sucrose, galactose, and cellobiose while mannose and rhamnose were not used.Isolated sugar maple tissue which had been subcultured on the same medium for a long period was found to undergo nutritional changes which enabled the tissue to adapt to the medium. The starch-digestion enzyme activity of the tissue was found to increase when sugar maple tissue was placed on soluble starch medium.

Influence of Temperature on Effects of Growth Regulators on Hypocotyl Elongation

Influences of temperature on effects of growth regulator on hypocotyl elongation of cucumber seedling were analized with the use of bromocholine bromide and gibberellic acid under the controlled temperature in phytotron.Seeds of cucumber (Cucumis sativus L. “Santo”) were sown in plastic containers filled with burnt chaff. The bottom of the container was kept being soaked in water to moisten the burnt chaff, and sown seeds were incubated at 25°C. One day after germination, each of the solutions of 5 ×10-3M bromocholine bromide (BCB) and 100 ppm gibberellic acid (GA) which contains 85% of GA3 was sprayed on cotyledons of the cucumber seedlings. At the same time, the hypocotyl unit was marked; the hypocotyl of each seedling was marked with ink at cotyledonary node and at a distance 1 cm below the cotyledonary node. The treated seedlings were cultured at 20°C, 25°C, 30°C and 35°C respectively. The length of the hypocotyl unit was measured every day.The elongation of the hypocotyl unit was inhibited by BCB and was promoted by GA under the temperature conditions of 20°C, 25°C, 30°C and 35°C. At the same time, the elongation of the hypocotyl unit was remarkably affected by temperature. The difference between the length of hypocotyl unit of treated seedlings and that of untreated ones was large at higher temperature and was small at lower temperature. While, the ratio of the length of the hypocotyl unit of the treated seedling to that of untreated seedling indicated that the promotive effect of GA on the hypocotyl elongation is small at 35°C, and also indicated that the inhibitory effect of BCB on the hypocotyl elongation is small at 20°C.These facts suggest that the temperature of envi-ronment should be taken into consideration for the analysis of the effects of the growth regulator.

Response of 'Perlette' Grape Berries to Gibberellic Acid Applied during Bloom or at Fruit Set

The response of the 9Perlette9 grape variety to gibberellic acid applied during the bloom or fruitset stage was studied in commercial vineyard trials in the Coachella and San Joaquin Valleys and at the University of California, Davis. Applications of 10 ppm during bloom in the commercial vineyards and 15 ppm at Davis effected thinning in only 3 of 5 trials in 1968. Berry size response to fruit-set sprays at concentrations of 40-80 ppm was significant in all trials, however. In 1969, concentrations of 2.5 and 10 ppm during bloom were ineffective in loosening the clusters in a Coachella trial, although significant response in berry size, increase resulted from fruitset applications of 50 and 80 ppm gibberellic acid in 2 additional tests.

Berry Set Response of ‘Thompson Seedless’ Grapes to Prebloom and Bloom Gibberellic Acid Treatment1

Abstract In 1967, 10 ppm of gibberellic acid (GA) applied to ‘Thompson Seedless’ grape inflorescences 10 days before bloom reduced the set of normal berries by 20%. In 1968, either 10 or 30 ppm GA applied 10 days before bloom reduced berry set by 8.2% and similar treatments applied at the beginning of bloom (< 1% of calyptras had fallen) reduced berry set by 21%. GA applied at 50% or 70% bloom was ineffective as a thinning agent and increased shot-berries in proportion to concentration. Direct counts of berries set relative to number of flowers present are necessary to estimate fruit thinning responses.

Estimation of the course of dormancy of potato tubers during growth and storage, with the aid of gibberellic acid

In order to estimate dormancy during growth and storage, tubers of six potato varieties were lifted at four dates, with fortnightly intervals, and stored for 0, 1, 2, 3, 4, 7, 9 and 11 days, after which their apical eyepieces were immersed in 0,1, or 5 ppm gibberellic acid.

Correlation between Hardiness and Free Amino Acid Content of Apple Seedlings Treated with Gibberellic Acid and Abscisic Acid1

Abstract Seedling apple trees of the ‘Rome Beauty’ variety were treated with 20 ppm abscisic acid and 100 ppm gibberellic acid and compared with controls during predormancy and dormancy for killing point, soluble protein and content of specific amino acids. Amino acid and soluble protein content were statistically correlated with killing point. A relationship exists between cold hardiness and certain amino acids. Soluble protein content was correlated with killing point in the gibberellic acid and control treatments. Treatment with abscisic acid showed no correlation between soluble protein and killing point indicating that soluble protein may not be an index of hardiness in apple trees.

Effects of Gibberellic Acid and Deflowering Upon Runner and Inflorescence Development in an Everbearing Strawberry1

Abstract Sprays of gibberellic acid (GA) were applied to new and 1-year-old plantings of the everbearing strawberry variety ‘Geneva’ during June, July and August in attempts to increase the production of runner plants and/or reduce the need for manual deflowering. Single applications of GA in June or double applications in June and July inhibited flowering, promoted runner development, and increased the yields of marketable runner plants the following year. Fifty ppm GA was as effective as higher concentrations. Deflowering had little effect upon runner initiation, but promoted flowering and increased the yields of runner plants. Maximum yields of runner plants resulted from combining GA sprays with deflowering.

Effect on 'Thompson Seedless' Fruit of Gibberellic Acid Bloom Sprays and Double Girdling

The thinning of <i>Vitis vinifera</i> L. `Thompson Seedless9 fruit in response to gibberellic acid (GA) applied to vines during bloom was studied in Kern County, California. Also included was the response to GA treatment of fruit on double-girdled vines. With crop level per vine held constant, commercially mature clusters were significantly looser on vines sprayed with 5, 15, and 25 ppm GA at 10, 60, and 95% bloom than on unsprayed vines. The main reason was fewer berries per cm on The basal four laterals. Clusters were loosest from treatments at 60% bloom. Density of berries on hand-thinned clusters was significantly greater for thinning before than after shatter. Fruit from vines sprayed at 1.0 and 60% bloom shattered more during postharvest handling than fruit from unsprayed vines. Shot berries were fewer with prebloom thinning than with GA sprays applied during bloom, with the percentages of the latter related directly to the GA concentration and time of treatment being greatest for 10% bloom and least for 95%. The percentages were greater on the first and second laterals than on the third and fourth. Water berry formation was not conclusively affected by the concentration and timing of GA sprays. Thinning, whether done by hand before bloom or during bloom with GA sprays, increased the variability of water berry formation among the basal four laterals of the clusters. The degree Balling and Balling-acid ratio of fruit were significantly higher for hand-thinned before bloom and GA-thin ned during bloom than for vines thinned after shatter. They were also significantly higher for GA-thinned fruit than for hand-thinned fruit. Concentration of GA and time of application had no clear effect on either the degree Balling or Balling-acid ratio. Although berry size showed no clear relation to degree Balling in any treatment, it was directly related to Bailing-acid ratio in all but the unthinned treatment with very small berries (because the percentage of total acid decreased as berry size increased). The degree Balling was significantly higher for vines double-girdled at shatter or single-girdled at shatter plus another girdling when the fruit was 8-10°B than for vines single-girdled at shatter or single-girdled at shatter and the girdle reopened when the fruit was 8-10°B. Within, each pair of treatments the difference was not significant.

Relief of Radiation-Induced Dormancy in Seeds of Phacelia tanacetifolia

Gibberellic acid (GA) counteracted the inhibitory effect of continuous tungsten irradiation on the germination of seeds of Phacelia tanacetifolia. The extent of reversal of the inhibition varied with the level of irradiation, temperature, and concentration of GA and was nearly complete under 2 ft-c at 10⚬ C with 250 ppm GA. GA and the factors involved in the radiation-inhibition appeared to act independently. No evidence was found for the involvement of auxin metabolism in the response.

Effect of cutting and gibberellin treatment on autumn-grown seed potatoes for spring planting

Length of dormancy limits the use of autumn-grown seed potatoes for planting the spring crop. Trials of different treatments for breaking dormancy were carried out for four successive seasons (1958–1961). Cutting the seed and dipping in gibberellic acid (GA) was effective in breaking dormancy. Cutting two weeks before planting and dipping the seed pieces in a 1 ppm GA solution gave the best results. Instead of cutting, smaller sized seed can be pierced, thus enabling the entire yield of tubers to be used for seed. Higher concentrations of GA induced growth abnormalities in both plants and tubers without producing any improvement in the breaking of dormancy over the lowest concentration used (1 ppm). Physiological aspects of seed potatoes are discussed.