Suppression Of Vegetative Growth Research Articles

From retrograde signaling to flowering time

Plant's transition from vegetative to reproductive phase is balanced by intricate cascade of genes regulated by both endogenous and environmental inputs. Stress causes suppression of vegetative growth and acceleration of flowering as an emergency response for preservation of the species. Recently, we determined that expression levels of a transcription factor with 2 B-Box motifs, BBX19, is notably reduced in response to accumulation of high levels of Methylerythritol cyclodiphosphate (MEcPP), a plastidial produced isoprenoids intermediate that also functions as a stress-specific retrograde signaling metabolite. We now have identified BBX19 as a repressor of Flower locus T (FT) expression and the corresponding downstream genes, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), Leafy (LFY) and Fruitful (FUL), through competition with CONSTANS (CO). Collectively our finding identifies BBX19 as a link between the stress-specific retrograde signal MEcPP and regulation of flowering time by depleting the active CO pool required for transcription of FT.

CaJOINTLESS is a MADS-box gene involved in suppression of vegetative growth in all shoot meristems in pepper

In aiming to decipher the genetic control of shoot architecture in pepper (Capsicum spp.), the allelic late-flowering mutants E-252 and E-2537 were identified. These mutants exhibit multiple pleiotropic effects on the organization of the sympodial shoot. Genetic mapping and sequence analysis indicated that the mutants are disrupted at CaJOINTLESS, the orthologue of the MADS-box genes JOINTLESS and SVP in tomato and Arabidopsis, respectively. Late flowering of the primary and sympodial shoots of Cajointless indicates that the gene functions as a suppressor of vegetative growth in all shoot meristems. While CaJOINTLESS and JOINTLESS have partially conserved functions, the effect on flowering time and on sympodial development in pepper, as well as the epistasis over FASCICULATE, the homologue of the major determinant of sympodial development SELF-PRUNING, is stronger than in tomato. Furthermore, the solitary terminal flower of pepper is converted into a structure composed of flowers and leaves in the mutant lines. This conversion supports the hypothesis that the solitary flowers of pepper have a cryptic inflorescence identity that is suppressed by CaJOINTLESS. Formation of solitary flowers in wild-type pepper is suggested to result from precocious maturation of the inflorescence meristem.

Response of ‘Tifway’ Bermudagrass to Trinexapac-ethyl

ABSTRACT The suppression of vegetative growth of turfgrasses can be achieved by the use of plant growth regulators (PGRs). One or two applications of trinexapac-ethyl PGR were applied at four rates to ‘Tifway’ bermudagrass [Cyrtodon dactylon (L.) Pers. × C. transvaalensis (Burtt-Davy)] in three studies to evaluate growth suppression and phytotoxicity. When the plant growth regulator was applied at 0.2 kg ha−1 in a single application, the vegetative growth was suppressed 30 to 34% at 2 weeks after treatment. Suppression was reduced from 17 to 24% by 4 weeks and < 12% by 6 weeks. Vegetative growth suppression at 6 weeks was higher (13 to 23%) in plots treated once with 0.4 kg ha−1 compared to those treated once at 0.2 kg ha−1 (6 to 12%). There was no advantage in vegetative suppression from split trinexapac-ethyl applications when compared to a single application when each was applied at the same total rate. The quality of ‘Tifway’ bermudagrass was reduced by trinexapac-ethyl applied at rates 0.2, 0.4, and ...

Frequency of Mowing and Plant Growth Regulators to Suppress Common Bermudagrass

A field experiment was conducted to evaluate plant growth regulators (PGRs) and mowing frequency for suppression of vegetative growth and seedhead development of common bermudagrass [Cynodondactylon (L.) Pers.]. Imazethapyr [2-[4,5-dihydro-4-methyl- 4-(1-methylethyl-5-oxo-1H-imidazol-2-y1]-5-ethyl-3-pyridinecarboxylic acid) applied at 0.06 kg ha¯¹ in each of two applications suppressed vegetative growth for five weeks when compared with untreated check. Turf treated with imazethapyr required two mowings during the next two weeks during 1990 and one mowing during the same period during 1991. Imazethapyr at 0.03 kg ha¯¹ applied in each of two applications plus one mowing at six weeks effectively suppressed common bermudagrass seedheads for seven weeks. Imazethapyr reduced turf quality within three weeks after treatment but the turf recovered by five weeks with no stand loss. Mefluidide [N-[2,3-dimethyl-5-[[(trifluoromethyl)sulfony]amino]phenyl]acetamide] applied at 0.6 kg ha¯¹ in each of two applications pl...

Reproductive Morphology of Five Kentucky Bluegrass Cultivars

AbstractA problem associated with plant growth retardant applications in Kentucky bluegrass, Poa pratensis L., is the application window for effective seedhead and vegetative growth suppression. Theoretically, the optimum timing for growth retardant applications would be just prior to the peak growth period in spring and before the inflorescence becomes visible above the youngest leaf. The objective of this field study was to determine if time of primordia initiation as an indicator of inflorescence development is consistent in selected Kentucky bluegrass cultivars in successive growing seasons. Initiation of inflorescence primordia was determined by randomly sampling and dissecting primary tillers of each cultivar during the late winter‐early spring and observing under a dissecting microscope. Our research showed that dates marking a transition from vegetative toward a predominately reproductive growth habit varied significantly among Kentucky bluegrass cultivars in both years. Also, one of the six cultivars, Kenblue “low maintenance” was not in a similar reproductive condition on several observation dates occuring in the same calendar week of 1986 compared with 1987. These results, based on our 2‐yr study, show that reproductive variation exists among Kentucky bluegrass cultivars, and that some cultivars may not develop inflorescences annually within calendar date application windows for growth retardants with much predictability.

Sequential Herbicide and Plant Growth Regulator Treatments on Bermudagrass (Cynodonspp.)

Sequential applications of MSMA plus metribuzin with selected plant growth regulators interacted synergistically and increased injury of ‘Tifway’ bermudagrass 1 and 2 wk after treatment. However, the higher injury at 3 wk after treatment, from sequential MSMA plus metribuzin with flurprimidol plus mefluidide or paclobutrazol with mefluidide, was additive. The vegetative growth suppression of bermudagrass at 2 wk after treatment with 2,4-D plus mecoprop plus dicamba with flurprimidol was antagonistic. The higher growth suppression 2 wk after treatment for MSMA plus metribuzin and flurprimidol plus mefluidide was additive compared to flurprimidol with mefluidide alone.

Vegetative Growth Suppression by Paclobutrazol in Greenhouse-grown `Pinot noir' Grapevines

Paclobutrazol (PB) soil drenches applied at 0, 10, 20, 30, 40, or 50 mg·liter-1 to potted Vitis vinifera L. `Pinot noir' vines inhibited extension growth of shoots on untopped vines and growth of lateral shoots on topped vines. Internode length, leaf area, and cane maturity were also reduced by the PB soil drenches. Foliar application of gibberellic acid (GA3) appeared to remove the effects of PB on the length of some internodes. Chemical name used: β[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

Growth Suppression of ‘Kenblue’ Kentucky Bluegrass Using Plant Growth Regulators and Degree Day Application Timing

AbstractPlant growth regulator (PGR) applications for seedhead and vegetative growth suppression have given inconsistent results from year to year when application timing is based on calendar days. Application timing based on growing degree days (GDD) should provide uniform and consistent results over time. These field studies were conducted to determine the window of application, based on GDD, for seedhead and vegetative growth suppression of Kentucky bluegrass. Mefluidide (N‐|2,4‐dimethyl‐5‐[[(trifluoromethyl)‐sulfonyl] amino] phenyl] acetamide) at 0.28 kg ha−1 and amidochlor (N‐[(acetylamino) methyl]‐2‐chloro‐N‐(2,6‐diethylphenyl) acetamide) at 2.8 kg ha−1 were applied to a uniform stand of Kentucky bluegrass [Poa pratensis (L.) ‘Kenblue’] at 25, 50, 75, 100, 125, and 150 GDD. Trials were conducted at East Lansing, MI in 1985 and 1986, and Columbus, OH in 1986. Soil type at East Lansing was an Owosso‐Marlette sandy loam complex (fine‐loamy, mixed, mesic Typic Glossoboric Hapludalf). Soil at Columbus was a Brookston silty‐clay loam (fine‐loamy, mixed, mesic Typic Agriaquoll). Application of PGR between 25 and 125 GDD provided excellent (&gt;86%) seedhead control. Mefluidide and amidochlor applications at 150 GDD gave 31 and 24% seedhead control, respectively, indicating that seedhead control was lost with this application timing. Clipping weights at East Lansing varied between years with only the 150 GDD application in 1985 and the 75 GDD application in 1986 differing significantly from the other application timings. However, the 75 GDD treatment in 1986 had reduced PGR activity because of rainfall 5 h after application. Application timing of PGR appeared to have no significant effect on the degree of vegetative growth suppression. However, GDD timed PGR applications are a valid technique for seedhead control in Kentucky bluegrass.

Growth and Fruiting of ‘Heritage’ Primocane Fruiting Red Raspberry in Response to Paclobutrazol

Abstract Paclobutrazol (PP333) was applied to dormant ‘Heritage’ primocane fruiting red raspberry (Rubus idaeus L.) plants at dosages of 0, 6, 12, 24, 48, and 96 mg a.i.·0.37 m−2 ·hill−1. After 29 days of fruit production, the average cumulative fruit yield of primocanes treated with 24, 48, or 96 mg of paclobutrazol was 92% greater than for control primocanes. The cumulative fruit yield of primocanes receiving the 24-mg dosage remained significantly greater through 50 days of production compared to that of control primocanes. Cumulative fruit yield was not adversely affected at any time during the production season by any of the dosages applied. The 24-mg dosage suppressed final primocane height by 19% but did not significantly decrease primocane diameter or the number of nodes formed. The vegetative responses to 48- and 96-mg dosages were similar, with an average reduction in primocane height, diameter, and total number of nodes formed of 36%, 25%, and 14%, respectively. Early onset of anthesis was positively correlated (r = 0.72) with suppression of vegetative growth. Production midpoint occurred 60 ± 3.7 days after initial anthesis and varied (r = 0.85) with the date of first anthesis. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).