scholarly journals A Cytokinin Analog Thidiazuron Suppresses Shoot Growth in Potted Rose Plants via the Gibberellic Acid Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Fisun G. Çelikel ◽  
Qingchun Zhang ◽  
Yanlong Zhang ◽  
Michael S. Reid ◽  
Cai-Zhong Jiang
Keyword(s):  
Gibberellic Acid ◽  
Shoot Growth ◽  
Shoot Elongation ◽  
Ethylene Biosynthesis ◽  
Silver Thiosulfate ◽  
Cell Architecture ◽  
Leaf Yellowing ◽  
Genes Encoding ◽  
Acid Pathway ◽  
Ga Biosynthesis

Application of thidiazuron (N-phenyl-N′-1,2,3-thiadiazol-5-ylurea, TDZ), a cytokinin analog, to inhibit the leaf yellowing that occurs after pinching potted rose plants, resulted in compact plants with shorter shoots and thicker internodes. Two weeks after treatment with 100 μM of TDZ, new shoots were half as long as those in control plants, and stem diameters were about 40% greater. This effect of TDZ is associated with changes in cell architecture. Although TDZ treatment stimulated ethylene production by the plants, inhibitors of ethylene biosynthesis (2-aminoethoxyvinyl glycine) or action (silver thiosulfate) did not affect the response of plants to TDZ. We found that TDZ treatment significantly suppressed the expression of bioactive gibberellic acid (GA) biosynthesis genes encoding GA3 and GA20 oxidases and slightly increased the expression of GA catabolism genes encoding GA2 oxidase. Application of GA3 and TDZ together resulted in normal elongation growth, although stem diameters were still somewhat thicker. Our results suggest that TDZ regulates shoot elongation and stem enlargement in potted rose plants through the modulation of bioactive GA biosynthesis.

Dormancy and Root Regeneration of Northern Red Oak

1975 ◽  
Vol 5 (2) ◽  
pp. 176-185 ◽  
Author(s):  
R. E. Farmer Jr
Keyword(s):  
Abscisic Acid ◽  
Gibberellic Acid ◽  
Root Growth ◽  
Shoot Growth ◽  
Starch Content ◽  
Shoot Elongation ◽  
Northern Red Oak ◽  
Root Regeneration ◽  
Physiological Dormancy ◽  
Hydrolysis Of

In a greenhouse forcing study, root regeneration was correlated with shoot growth, which began with increasing rapidity as chilling requirements were met. Root growth was stimulated by factors originating in the stem of both dormant and growing plants, though root regeneration during physiological dormancy was limited. Auxins applied to decapitated plants stimulated root regeneration while inhibiting shoot growth; gibberellic acid, kinetin, ethylene, and abscisic acid had no direct effect upon root regeneration. The starch content of roots averaged 41% during dormancy, and major hydrolysis of starch was dependent upon initiation of shoot elongation.

scholarly journals 107 Silver Thiosulfate (STS) Alone and in Combination with Gibberellic Acid (GA3) in the Forcing Solution Influences Budbreak and Shoot Elongation of Dormant Woody Plant Species

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 460A-460
Author(s):  
Bahget T. Hamooh ◽  
Paul E. Read
Keyword(s):  
Gibberellic Acid ◽  
Effective Treatment ◽  
Woody Plants ◽  
Woody Plant ◽  
Shoot Elongation ◽  
Shoot Length ◽  
Solution System ◽  
Silver Thiosulfate ◽  
Cornus Alba ◽  
Forcing Solution

Research was conducted to further modify the forcing solution system in order to expedite the propagation of woody plants, such as Spiraea canescens, Lonicera maakii, and Cornus alba. Time of immersion in solutions containing 5 mM silver thiosulfate (STS) was compared with the basic forcing solution reported by Yang and Read (1989), a solution containing 200 mg 8-hydroxyquinoline citrate per liter and 2% sucrose. Other treatments employed were gibberellic acid (GA3) 50 mg per liter for 24 h and a combination of STS and GA3 for the same amount of time. Increasing the time in STS solution up to 24 h led to higher percent budbreak and shorter time to budbreak for all the three species examined. The combination of STS and GA3 was the most effective treatment overall in reducing time of budbreak and increasing percent of budbreak. All STS treatments studied showed similar responses in shoot elongation. However, treatments with GA3 alone, and in combination with STS showed more than a doubling in shoot length compared to all STS treatments studied and the control. Implications based on SEM observations will be presented.

scholarly journals Trinexapac-ethyl Restricts Shoot Growth and Prolongs Stand Density of 'Meyer' Zoysiagrass Fairway Under Shade

HortScience ◽  
2002 ◽  
Vol 37 (3) ◽  
pp. 502-505 ◽  
Author(s):  
E.H. Ervin ◽  
C.H. Ok ◽  
B.S. Fresenburg ◽  
J.H. Dunn
Keyword(s):  
Shoot Growth ◽  
Management Practice ◽  
Acid Ethyl Ester ◽  
Stand Density ◽  
Shoot Elongation ◽  
Golf Course ◽  
Effective Management ◽  
Mature Stand ◽  
Tiller Density ◽  
Ga Biosynthesis

'Meyer' zoysiagrass (Zoysia japonica Steud.) is a popular turfgrass species for transition zone golf course fairways and tees because it is generally winter hardy while providing an excellent playing surface with minimal chemical and irrigation inputs. However, its functionality declines readily on many of the shaded areas on these courses. Reduced irradiance causes excessive shoot elongation, reduced tillering, and weak plants that are poorly suited to tolerate or recover from traffic and divoting. Trinexapac-ethyl (TE) effectively reduces gibberellic acid (GA) biosynthesis and subsequent shoot cell elongation. The objective of this study was to determine if monthly applications of TE would reduce shoot elongation of 'Meyer' zoysiagrass and improve stand persistence under two levels of shade. Shade structures were constructed in the field that continuously restricted 77% and 89% irradiance. A mature stand of 'Meyer' was treated with all combinations of three levels of shade (0%, 77%, and 89%) and three levels of monthly TE application [0, 48 g·ha-1 a.i. (0.5×), and 96 g·ha-1 a.i. (1×)] in 1998 and 1999. In full sun, the 0.5×-rate reduced clipping production by 17% to 20% over a four-week period and the 1×-rate by 30% to 37%. Monthly application of TE at the 1×-rate increased 'Meyer' tiller density in full sun and under 77% shade. Both rates of TE consistently reduced shoot growth under shade relative to the shaded control. Only the monthly applications at the 1×-rate consistently delayed loss of quality under 77% shade. The zoysiagrass persisted very poorly under 89% shade whether treated or not with TE and plots were mostly dead at the end of the experiment. Our results indicate TE can be an effective management practice to increase 'Meyer' zoysiagrass persistence in shaded environments. Chemical name used: 4-cyclopropyl-α-hydroxy-methylene-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl)

scholarly journals Induction of Dormancy in Nondormant Seeds

1994 ◽  
Vol 119 (3) ◽  
pp. 408-413 ◽  
Author(s):  
Anwar A. Khan
Keyword(s):  
Abscisic Acid ◽  
Lycopersicon Esculentum ◽  
Gibberellic Acid ◽  
Lactuca Sativa ◽  
Daucus Carota ◽  
Apium Graveolens ◽  
Lettuce Seeds ◽  
Moist Chilling ◽  
Dormancy Induction ◽  
Ga Biosynthesis

A gibberellic acid (GA) biosynthesis inhibitor, tetcyclacis, induced dormancy in nondormant seeds of lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), carrot [Daucus carota var. sativus (Hoffn.)], onion (Allium cepa L.), celery (Apium graveolens L.), and impatiens (Impatiens novette), as most of the seeds failed to germinate after washing under conditions that permitted germination before dormancy induction. In lettuce seeds, tetcyclacis and paclobutrazol were more effective in inhibiting germination in light than in darkness. A 16- to 24-h soak treatment with tetcyclacis was sufficient to induce dormancy in nearly all seeds. Tetcyclacis failed to induce dormancy if applied after 6 h presoak in water. Dormancy induced by tetcyclacis was released by GA4+7 (a mixture of gibberellin A4 and A7), light, and moist-chilling treatments. When GA4+7 was applied with tetcyclacis, dormancy induction was prevented under both favorable, e.g., 25C, and unfavorable, e.g., 5C, or low water potential (Ψ), germination conditions. Unlike tetcyclacis, abscisic acid (ABA) failed to induce dormancy in lettuce seeds. Thermodormancy induction in lettuce seeds at 35C was prevented by fluridone. However, neither ABA nor tetcyclacis countered its effect. Dormancy was also induced in lettuce seeds by ancymidol, flurprimidol, or paclobutrazol. Dormancy induced by tetcyclacis in pepper, tomato, carrot, and onion seeds was released by GA4+7, but not by irradiation or moist-chilling. Chemical names used: 5-(4-chlorophenyl)-3, 4, 5, 9, 10-pentaazatetracyclo [5.4.102,6.08,11]-dodeca-3, 9-diene (tetcyclacis); 1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1, 2, 4-triazole-1-yl)-3-pentanol (paclobutrazol); α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol); α-(1-methyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidine-methanol (flurprimidol); 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4 (1H)-pyridinone (fluridone).

Germination Characteristics of Bear Oak

1977 ◽  
Vol 1 (1) ◽  
pp. 19-20 ◽  
Author(s):  
Roosevelt Allen ◽  
Robert E. Farmer
Keyword(s):  
Gibberellic Acid ◽  
Root Growth ◽  
Leaf Area ◽  
Shoot Elongation ◽  
Germination Characteristics ◽  
Nursery Production ◽  
Quercus Ilicifolia ◽  
Spring Planting

Abstract Freshly collected bear oak (Quercus ilicifolia Wangenh.) seed from southwestern Virginia exhibited root growth under a range of temperatures but had epicotyl dormancy which was broken by stratification or gibberellic acid (GA3). Shoot elongation resulting from six weeks' chilling or GA3 was also influenced by temperature; a regime of 64°-75°F enhanced both percentage of seed with elongated shoots and leaf area per shoot relative to a 45°-61°F regime. Germination characteristics of seed lots from individual open-pollinated trees varied widely. Results suggest that fall-seeded beds will be most suitable in nursery production and that container stock for spring planting can be produced under greenhouse conditions with fall-stratified seed planted in early January.

Shoot morphology and shoot growth potential in 1-year-old Scots pine seedlings

1981 ◽  
Vol 11 (4) ◽  
pp. 789-795 ◽  
Author(s):  
S. Thompson
Keyword(s):  
Scots Pine ◽  
Shoot Growth ◽  
Growing Season ◽  
Shoot Elongation ◽  
Growth Potential ◽  
Shoot Morphology ◽  
Growing Seasons ◽  
Pine Seedlings

When seedlings of a single seed source of Scots pine (Pinussylvestris L.) were raised for 26 weeks in a naturally lit, heated greenhouse, two types of shoot morphology were observed. Type 1 was that normally found in 1-year-old seedlings. Type 2 had a shoot morphology similar to that of seedlings raised outdoors for two growing seasons. When compared with type 1 plants, type 2 plants had an earlier start to shoot elongation, set their buds earlier, and stopped shoot elongation sooner. After one growing season, type 2 plants were shorter, had fewer stem units for shoot elongation in the second season, but carried a greater foliage biomass than 1-year-old type plants. After two seasons they remained shorter. Thus, plant rearing practices which result in the production of seedlings with this type of shoot morphology arc undesirable.The relationship between early "budsct," shoot morphology, and plant height suggests that the proportion of seedlings with a 2-year-old shoot morphology after one growing season in a heated greenhouse may be used as an early test for height growth potential in seed origins and possibly in progenies of north temperate pine species.

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