Factors that influence dormancy in milkweed seeds

1972 ◽  
Vol 50 (4) ◽  
pp. 713-718 ◽  
Author(s):  
T. Oegema ◽  
R. A. Fletcher
Keyword(s):  
Abscisic Acid ◽  
Synergistic Effect ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Seed Coat ◽  
Germination Percentage ◽  
Endogenous Gibberellin ◽  
Growth Promoters ◽  
Asclepias Syriaca ◽  
Alternating Temperature

Seeds of Asclepias syriaca L. (milkweed) have an inherent dormancy and these seeds could be forced to germinate by various treatments including stratification, cutting or removal of the seed coat, gases, alternating temperature, and a number of chemicals. Of the various treatments, the growth regulators kinetin and gibberellic acid were most effective in overcoming dormancy and a combination of these two had a synergistic effect. The increased germination percentage after 5 weeks of stratification was not accompanied by an increase in endogenous gibberellin levels. Treatment of the seeds with abscisic acid after stratification resulted in a complete inhibition of germination whereas treatment with kinetin resulted in an increase in germination. It is concluded that dormancy in milkweed seeds could be broken by many factors and regulated by an intricate interplay between growth promoters and inhibitors.

Dormancy in seeds of Hibbertia cuneiformis and H. huegelii (Dilleniaceae)

1997 ◽  
Vol 45 (6) ◽  
pp. 1045 ◽  
Author(s):  
A. Schatral ◽  
J. M. Osborne ◽  
J. E. D. Fox
Keyword(s):  
Abscisic Acid ◽  
Gibberellic Acid ◽  
Seed Coat ◽  
Diurnal Cycle ◽  
Plant Hormones ◽  
Germination Percentage ◽  
Complete Darkness ◽  
Embryo Dormancy ◽  
Chemical Inhibition ◽  
Germination Experiments

Dormancy delays the germination of seeds in two species of the primitive angiosperm genus Hibbertia (H. cuneiformis and H. huegelii, family Dilleniaceae). After seed coat removal, germination increased in 18-month-old seeds of H. cuneiformis and 6- to 8-month-old seeds of H. huegelii. Hence, seeds of the two species exhibit seed coat dormancy. The removal of the seed coat may stimulate germination, as the result of increased water uptake, and/or the removal of mechanical and chemical inhibition. However, the occurrence of imbibitional injury and a reduced percentage of vigorous seedlings in decoated seeds suggest that embryo dormancy, as a second type of dormancy, impedes germination in H. cuneiformis. Embryo dormancy also delays the germination of seeds of H. huegelii, since a high percentage of seeds did not germinate after removal of the seed coat. Embryo dormancy appears to vary among individual seeds and between species. The germination experiments suggest a high percentage of non-dormant and weakly dormant embryos for 18-month-old seeds of H. cuneiformis. By contrast, many seeds of H. huegelii appear to contain deeply dormant embryos. In H. cuneiformis, the depth of the seed dormancy varied with the age of the seeds. Freshly harvested seeds did not germinate for 3 months. Treatment with gibberellic acid (GA3) (120 mg L-1) significantly enhanced germination of freshly harvested and 18-month-old, intact seeds of H. cuneiformis and the germination of decoated 18-month-old seeds of H. huegelii. The plant hormones kinetin and abscisic acid did not affect the final germination percentage in 18-month-old seeds of H. cuneiformis. For H. huegelii, germination was reduced in decoated seeds and seeds with cracked coats exposed to an 8 h day: 16 h night diurnal cycle compared with complete darkness.

Manipulating dormancy of capeweed (Arctotheca calendulaL.) seed

1998 ◽  
Vol 8 (2) ◽  
pp. 139-146 ◽  
Author(s):  
Ali Tadayyon Chaharsoghi ◽  
Brent Jacobs
Keyword(s):  
Gibberellic Acid ◽  
Growth Regulators ◽  
Germination Percentage ◽  
Preliminary Assessment ◽  
Natural Conditions

AbstractCapeweed (Arctotheca calendula) seeds were found to be dormant at harvest. Effects of duration and temperature of storage under ‘laboratory’ and ‘natural’ conditions, growth regulators, stratification and age of seeds, were studied on the germination of dormant seeds. Three factors imposed on seeds were found to promote germination of capeweed: (i) allowing seed to age, either in storage, buried in soil or during stratification (germination of 18-month-old seeds was up to 60% higher than that of fresh seeds); (ii) the presence of light (the average germination percentage of seeds exposed to light during storage was 3.2-fold greater than that of seed stored in the dark); and (iii) the application of growth regulators, particularly gibberellic acid, enhanced by scarification (GA3and ethephon promoted germination by up to 58% when applied to scarified seeds). Other factors, e.g. temperature and depth of storage, influenced germination but were less critical to its success. These results provide a preliminary assessment of the importance of these factors in controlling dormancy in seeds of capeweed.

scholarly journals Influence of Seed Treatments on Germination and Initial Growth of Ornamental Palms

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 604E-604 ◽  
Author(s):  
Jose P. Morales-Payan ◽  
Bielinski M. Santos
Keyword(s):  
Nitric Acid ◽  
Gibberellic Acid ◽  
Seed Coat ◽  
Acid Treatment ◽  
Date Palm ◽  
Germination Percentage ◽  
Initial Growth ◽  
Chemical Treatments ◽  
Phoenix Canariensis ◽  
Physical And Chemical

Experiments were conducted in the Dominican Republic to determine the effect of physical and chemical treatments on the germination of the ornamental palms Roystonea hispaniolana Bailey (Royal palm), Acrocomia quisqueyana Bailey (Corozo palm), Sabal umbraculifera Mart (Cana palm), Phoenix canariensis (Canary Islands date palm), Veitchia merrillii (Becc) Bailey (Manila palm), Chrysalidocarpus lutescens Wendl (Areca palm), and Caryota urens (Fishtail palm). Treatments were seed immersion in water or gibberellic acid 3 (GA3) solution for 72 hours, immersion in concentrated nitric acid for 5 minutes, or cracking of the seed coat. Rate and percentage of emergence 90 days after treatment were measured. The best results for Roystonea, Phoenix, Veitchia, Caryota, and Chrysalidocarpus were obtained soaking the seeds in water or a 200-ppm gibberellic acid solution. Nitric acid and seed coat cracking significantly reduced the germination percentage in all the species, except Acrocomia guisqueyana and Sabal umbraculifera. Seeds of Acrocomia did not germinate as a response to any of the treatments tested. Sabal seeds germinated only after coat cracking or nitric acid treatment.

Dormancy-break and germination in seeds of Prunus campanulata (Rosaceae): role of covering layers and changes in concentration of abscisic acid and gibberellins

2007 ◽  
Vol 17 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Shun-Ying Chen ◽  
Ching-Te Chien ◽  
Jeng-Der Chung ◽  
Yuh-Shyong Yang ◽  
Shing-Rong Kuo
Keyword(s):  
Abscisic Acid ◽  
Seed Coat ◽  
Carotenoid Biosynthesis ◽  
Inhibitory Effect ◽  
Germination Percentage ◽  
Biosynthesis Inhibitor ◽  
Breaking Dormancy ◽  
Aba Content ◽  
Ga Biosynthesis

AbstractIntact seeds (seed+endocarp) from freshly harvested fruits of Prunus campanulata were dormant, and required 4–6 weeks of warm followed by 8 weeks of cold stratification for maximum germination percentage. Removing both endocarp and seed coat, however, promoted germination in a high percentage of non-stratified seeds. Treatment of intact, non-stratified seeds with gibberellic acid (GA3) was only partially effective in breaking dormancy. However, GA3 promoted germination of non-stratified seeds in which the endocarp (but not the seed coat) had been removed. The order of abscisic acid (ABA) concentration in fresh seeds was endocarp > seed coat > embryo, and its concentration in endocarp plus seed coat was about 6.2-fold higher than that in the embryo. Total ABA contents of seeds subjected to warm and/or cold moist stratification were reduced 6- to 12-fold. A higher concentration of GA4 was detected in embryos of non-dormant than in those of dormant seeds. Fluridone, a carotenoid biosynthesis inhibitor, was efficient in breaking dormancy of Prunus seeds. Paclobutrazol, a GA biosynthesis inhibitor, completely inhibited seed germination, and the inhibitory effect could be partially reversed by GA4, but not by GA3. Thus, dormancy in P. campanulata seeds is imposed by the covering layers. Dormancy break is accompanied by a decrease in ABA content of the covering layers and germination by an increase of embryonic GA4 content.

Effects of partial drying on seed germination in the aquatic grasses Zizania palustris L. and Porteresia coarctata (Roxb.) Tateoka

1992 ◽  
Vol 2 (4) ◽  
pp. 199-205 ◽  
Author(s):  
C. D. Aldridge ◽  
R. J. Probert
Keyword(s):  
Abscisic Acid ◽  
Seed Germination ◽  
Growth Regulators ◽  
Germination Percentage ◽  
Hormonal Status ◽  
Cold Stratification ◽  
Porteresia Coarctata ◽  
Germination Response ◽  
Fold Reduction ◽  
Germination Behaviour

AbstractPartial drying of non-dormant seeds had little effect on germination behaviour compared with undried controls. In contrast, partial drying resulted in a marked increase in the germination response of freshly harvested (dormant) seeds of Z. palustris. Partial drying also resulted in a 100-fold reduction in the concentration of gibberellins (GA4+7) required for maximum germination. Although the concentration range of applied abscisic acid (ABA) that permitted germination was unaltered, partial drying increased the final germination percentage at all concentrations tested. The concentration of ABA above which germination was reduced in freshly harvested (dormant) seeds of Z. palustris was 3.16 × 10−7m compared with 10−4m in fresh (non-dormant) seeds of P. coarctata. Changes in the germination response of Z. palustris seeds to applied growth regulators, following partial drying or cold stratification might be explained by similar changes in hormonal status.

scholarly journals GERMINATION OF VERBENA SEED IN RESPONSE TO PLANT GROWTH REGULATORS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1156c-1156
Author(s):  
Gamil A. Kabbabe ◽  
William J. Carpenter
Keyword(s):  
Polyethylene Glycol ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Traditional Method ◽  
Germination Percentage ◽  
Dry Storage ◽  
Gradual Loss ◽  
Acetone Treatment ◽  
Percent Germination ◽  
Peg 8000

Verbena seed when harvested, has a natural dormancy that gradually dissipates during a 5 to 8 month period of dry storage. In this study, the gradual loss of the dormancy causing factor was correlated with germination percentage. Acetone treatment of verbena seeds was found to cause a slight, but non-significant, reduction in total germination. However, the infusion of gibberellic acid (GA4/7) and kinetin (KIN) with the acetone at various concentrations improved germination. The traditional method of seed osmoconditioning using Polyethylene Glycol (PEG 8000) at -1.0 MPa caused a non-significant reduction in percent germination, similar to that with acetone. When growth regulators were mixed with the osmoconditioning solution, at the concentrations used with acetone, a definite and significant improvement in terms of rate and percent of germination was observed.

scholarly journals Effect of Gibberellic Acid and Indole 3-Acetic Acid on Seed Germination Performance of Horse gram (Macrotyloma uniflorum) Lam (Verdc)

2016 ◽  
Vol 1 (2) ◽  
pp. 36 ◽  
Author(s):  
J. Lalitha ◽  
Haseena Rafath ◽  
M. Subash
Keyword(s):  
Acetic Acid ◽  
Seed Germination ◽  
Plant Growth ◽  
Gibberellic Acid ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Germination Percentage ◽  
Potential Growth ◽  
Macrotyloma Uniflorum ◽  
Indole 3 Acetic Acid

The experiment was undertaken with an objective to investigate the effect of various concentrations of plant growth regulators, i.e., Gibberellic acid (GA3) and Indole 3-acetic acid (IAA) on seed germination of Macrotyloma uniflorum. Seeds were soaked for 12 hours in different concentrations substances (1.0, 2.0, 3.0 and 4.0 mg/L) of IAA, GA3 and control set was soaked only in distilled water.  Three replicates of each treatment with fifty seeds per replicate were arranged for precise physiological analysis. Significant variation was found in all aspects after analysis of variance (ANOVA) of each mean value. After two weeks of seed soaking, it was noted that germination percentages were significantly accelerated by lower concentrations (1 and 2 mg) of used hormones. Amongst the two potential growth regulators, 2 mg/L was found most effective because it showed highest germination percentage for IAA (93%) and GA3 (88%). A great deal of information relating to seed germination practices shows that these plant growth regulators were efficient in overcoming dormancy leading to rapid seed germination. IAA was selected as best hormone in this study, which showed highest seed germination (93%). 

scholarly journals Differences in Inflorescence Numbers and Endogenous Gibberellic Acid Levels in ‘Afterglow’ Bougainvillea

2020 ◽  
Vol 30 (6) ◽  
pp. 650-653
Author(s):  
Mun Wye Chng ◽  
Kimberly A. Moore
Keyword(s):  
Abscisic Acid ◽  
Light Intensity ◽  
Plant Growth ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Foliar Spray ◽  
Multiple Cues ◽  
Exogenous Aba ◽  
Long Day ◽  
Temperature Water

Bougainvillea (Bougainvillea sp.) plant inflorescence number will vary in response to multiple cues such as changes in temperature, water, light intensity, pruning, and photoperiod. Previous research reports that the application of plant growth regulators (PGRs) to bougainvillea grown under varying photoperiods improved inflorescence number, probably as a result of changes in gibberellic acid (GA) levels. There are many bioactive plant GAs, but we chose to investigate differences in gibberellic acid 3 (GA3) levels and inflorescence number in response to the application of ethephon (2-cholorethylphosponic acid) or abscisic acid (ABA) to ‘Afterglow’ bougainvillea (Bougainvillea ×buttiana) grown under 14-hour photoperiod [long-day (LD)] conditions. Plants were 5 inches tall with seven visible lateral nodes and were grown in a greenhouse in 4-inch pots filled with 5-mm coarse aquarium zeolite. Ethephon was applied as a foliar spray at 0.05, 0.07, 0.10, 0.15, or 0.20 mg/plant. ABA was applied as a soil drench at 1, 1.5, 3, 6, 8, or 10 mg/plant. Endogenous levels of GA3 were measured 1 and 48 days after treatment to calculate the change in GA3 (∆GA3). A short day (SD) control of 8 hours was included to measure differences in inflorescence number and ∆GA3 between photoperiods. ‘Afterglow’ plants grown under SD conditions had the greatest decrease in ∆GA3 (–1.09 µg·g–1) over 48 days and the most inflorescences (10.6) compared with LD control plants with a decrease in ∆GA3 of –0.09 µg·g–1 and fewer inflorescences (1.0). Plants grown under LD conditions and treated with 0.05 mg/plant ethephon had inflorescence numbers (9.6) and levels of ∆GA3 (–0.74 µg·g–1) similar to the SD control. As ethephon rate increased to more than 0.05 mg/plant, inflorescence number on LD plants decreased and ∆GA3 increased. Exogenous ABA rates of 1 mg/plant produced inflorescence numbers (1.4) and ∆GA3 (–0.10 µg·g–1) similar to the LD control. As the rate increased, ∆GA3 increased and inflorescence number decreased. Plants treated with ABA rates of 3 mg/plant and more were defoliated and had no inflorescences.

scholarly journals Hormonal regulation of the growth of leaves and inflorescence stalk in Muscari armeniacum Leichtl.

2016 ◽  
Vol 69 (1) ◽  
Author(s):  
Marian Saniewski ◽  
Justyna Góraj-Koniarska ◽  
Elżbieta Węgrzynowicz-Lesiak ◽  
Eleonora Gabryszewska
Keyword(s):  
Acetic Acid ◽  
Abscisic Acid ◽  
Plant Growth ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Hormonal Regulation ◽  
Present Experiment ◽  
Stem Growth ◽  
Flower Bud ◽  
Indole 3 Acetic Acid

It is known that chilling of <em>Muscari</em> bulbs is necessary for the growth of the inflorescence stalk and flowering, but not for the growth of leaves. Gibberellic acid (GA) accelerated stem growth and flowering in chilled <em>Muscari</em> bulbs. In the present experiment it was shown that in unchilled derooted <em>Muscari</em> bulbs the growth of leaves, but not the growth of the inflorescence stalk, was observed when bulbs were stored in water, GA at a concentration of 50 and 100 mg/L, benzyladenine (BA) at a concentration of 25 and 50 mg/L, or a mixture of GA+BA (50+25 mg/L), but abscisic acid (ABA) at a concentration of 10 mg/L greatly inhibited the growth of leaves. In chilled derooted <em>Muscari</em> bulbs the growth of leaves and inflorescence stalk was observed when bulbs were stored in water or GA, but BA and GA+BA treatments totally inhibited the growth of the inflorescence stalk without an effect on the growth of leaves. These results clearly showed that the growth of leaves and inflorescence stalk in <em>Muscari</em> bulbs are controlled by plant growth regulators in different ways. ABA totally inhibited the growth of leaves and inflorescence stalk in chilled derooted <em>Muscari</em> bulbs. It was shown that after the excision of the inflorescence bud in cultivated chilled <em>Muscari</em> bulbs, the inflorescence stalk died, but application of indole-3-acetic acid (IAA) 0.5% in the place of the removed inflorescence bud induced the growth of the inflorescence stalk. IAA applied under the inflorescence bud inhibited the development of flowers (flower-bud blasting) and induced the growth of the inflorescence stalk below the treatment site. These results are discussed with reference to hormonal regulation of stem (stalk) growth in tulip, narcissus, hyacinth, and <em>Hippeastrum</em>.

scholarly journals Breaking seed dormancy of Tulipa scardica Bornm. and Tulipa kosovarica Kit Tan, Shuka & Krasniqi by pre-chilling, plant growth regulators and some chemical treatments

2019 ◽  
Vol 113 (2) ◽  
pp. 203 ◽  
Author(s):  
Bekim GASHI ◽  
Mirsade OSMANI ◽  
Sali ALIU
Keyword(s):  
Sulfuric Acid ◽  
Plant Growth ◽  
Gibberellic Acid ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Potassium Nitrate ◽  
Germination Percentage ◽  
Dormancy Breaking ◽  
Germination Time ◽  
Mean Germination Time

<p><em>Tulipa scardica</em> and <em>T. kosovarica</em> are rare, endemic and endangered plants in Kosovo. This research was carried out to study the dormancy breaking treatment in Tulipa scardica and T. kosovarica seeds by pre-chilling and various concentration of potassium nitrate (KNO3), gibberellic acid (GA3), kinetin, thiourea and sulfuric acid (H2SO4). The experiment was conducted with untreated seeds (without stratification) and with stratified seeds (8 weeks) and treated with different concentration of some chemicals and plant growth regulators. Results showed that the final germination percentage (FGP) of seeds without stratification at both Tulipa plant species was zero, while germination was enhanced by pre-chilling (stratification) especially after treatment of these seeds by above mentioned treatments. Both Tulipa species showed an increase in mean germination time (MGT), an indication of slower germination, as different chemicals or plant growth regulators increased. Depending on treatments, germination was ranging from 80 % to 90 %, the maximum germination was detected in seeds treated with KNO3, GA3, and their combination, while the minimum germination in seeds without treatments and treated with thiourea. The conservation of these plants in botanic gardens by cultivation or propagation for commercial use as ornamental plants could give an effective contribution to the conservation of these plants.<br />Abbreviations: KNO<sub>3 </sub><strong>– </strong>potassium  nitrate; GA<sub>3 </sub>- gibberellic acid; H<sub>2</sub>SO<sub>4</sub> – sulfuric acid; FGP – final germination percentage; MGT – mean germination time<br /><br /></p>

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