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There are doubts about nitrogen (N) management and the use of growth regulator in wheat. Thus, the objective was to evaluate the wheat performance as a function of topdressing N applied at different phenological stages of crop, and the use of trinexapac-ethyl (TE) growth regulator associated with N fertilization in subtropical regions in southern Brazil. In each environment, two experiments were carried out, all with an experimental design in 2 × 4 factorial scheme. The factors in experiment 1 were topdressing N application at seedling emergence and tillering stages and N rates (0, 40, 80, and 120 kg N ha−1); and in experiment 2: use of TE (with and without) and N rates (0, 40, 80, and 120 kg N ha−1) applied at tillering. The augment of N in topdressing increases the lodging. The use of TE minimizes the lodging. In environment with irrigation, the application of intermediate N rates at crop emergence reduces lodging. The yield components are altered by the rates and stages of N application, with variable responses according to the cultivation environment. The stage of application does not affect grain yield. N fertilization increases the yield, being that in Ponta Grossa the wheat is more responsive to higher N input. In certain environments, TE reduces the number of spikes m−2 and increases the number of grains per spike. TE impairs yield when associated with N non-application in topdressing. On the other hand, it maximizes the effect of N fertilization on yield, when using higher N rates in topdressing. [ABSTRACT FROM AUTHOR]

Biostimulants such as seaweed extract can be strong allies in the formation of lawn plugs, as they assist in several physiological processes in the plant. At the same time, shoot mowing is the main factor in the maintenance cost of turfgrasses, and there is a search for alternatives to mechanical management without compromising aesthetic quality, such as the use of plant growth regulators (PGR). Thus, the objective of this experiment was to evaluate the use of Ascophyllum nodosum in the production of lawn seedlings, and growth regulators in the development of Carpet grass. The experiment was carried out between 2020 and 2021, and divided into two parts, the first being the production of seedlings (30 days) of Emerald grass, Bermudagrass DiscoveryTM, Carpet grass and Bahiagrass with the application of seaweed extract, in the second part the development of Carpet grass was evaluated after the application of PGRs (Trinexapac-ethy, Paclobutazol and Glyphosate) in 60 days. The evaluations performed were: green color index (GCI); normalized difference vegetation index (NDVI); root length and dry mass of seedlings. And for the second part: GCI; SPAD; NDVI; visual appearance; coverage rate; shoot height; growth rate and dry mass of clippings. It was observed that the use of the biostimulant increased the production of ornamental lawn plugs, where better values could be observed for Carpet grass. PGRs demonstrated efficient results for controlling the height of Carpet grass in up to 30 days, with emphasis on Trinexapac-ethyl, which reduced growth and maintained the aesthetics of the lawn.

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Progress in Plant Protection is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avances en Ciencias e Ingenierías (ACI) is the property of USFQ Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Lithuania, and co‐rapporteur Member State, Latvia, for the pesticide active substance trinexapac and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of trinexapac as a plant growth regulator on barley (winter and spring) and wheat (winter). MRLs were assessed in rye. The conclusions were updated with regard to the endocrine‐disrupting properties following a mandate received from the European Commission in January 2019.The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. The confirmatory data following the review of existing MRLs according to Article 12 of Regulation (EC) No 396/2005 were also assessed under this conclusion. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Lithuania, and co‐rapporteur Member State, Latvia, for the pesticide active substance trinexapac and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of trinexapac as a plant growth regulator on barley (winter and spring) and wheat (winter). MRLs were assessed in rye. The conclusions were updated with regard to the endocrine‐disrupting properties following a mandate received from the European Commission in January 2019.The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. The confirmatory data following the review of existing MRLs according to Article 12 of Regulation (EC) No 396/2005 were also assessed under this conclusion. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

The relatively high temperature at Kessem sugarcane plantation in Ethiopia was hypothesized to justify the implementation of chemical ripeners as a strategic intervention to combat poor cane quality. Accordingly, a field experiment was carried out to assess the responsiveness of four sugarcane varieties (B52-298, NCo334, C86-12, and SP70-1284) to five ripener treatments: 2-chloroethylphosphonic acid (Ethephon™, 480 g ai L−1) at 720 g ai ha−1, fluazifop-p-butyl (Fusilade Forte™, 150 g ai L−1) at 25.6 g ai ha−1, trinexapac-ethyl (Moddus™, 250 g ai L−1) at 250 g ai ha−1, 2-chloroethylphosphonic acid + fluazifop-p-butyl combination at the mentioned application rates, trinexapac-ethyl + fluazifop-p-butyl combination at the mentioned application rates, and an untreated control. The experiment was conducted in a factorial arrangement in a randomized complete block design (RCBD) with three replications. The results showed that stalk height, stalk weight, sucrose content (%), and sucrose yield (t ha−1) were affected by the main effect of ripener treatment, but there was no significant cultivar x ripener treatment interaction for the parameters collected. Overall, the sequential application treatment of trinexapac-ethyl followed by fluazifop-p-butyl 28 days later performed the best and improved sucrose content and sucrose yield by 2.64% unit and 2.15 t ha−1, respectively. In economic terms, the trinexapac-ethyl + fluazifop-p-butyl sequential application treatment resulted in a marginal rate of return of 2393%. Therefore, the sequential trinexapac-ethyl + fluazifop-p-butyl ripener program was identified as a promising ripening strategy to be evaluated on a commercial scale at the sugarcane plantations in Ethiopia. [ABSTRACT FROM AUTHOR]

Application of regulators in production of pot plants have been increasing due to lowering growth, improving branching and the number of flowering branches. In order to study the effect of levels and application method of trinexapac-ethyl regulator on height control and morphophysiological characteristics and flowering of Zinnia elegans, a factorial experiment based on completely randomized design with three replications was performed. Zinnias seedlings were planted in polyethylene pots and subjected to trinexapac-ethyl with levels of zero, 2x10-3, 1x10-3, 0.5x10-3 and 4.5x10-4 g when the first bud emerged. Trinexapac-ethyl was applied in both foliar spray and soil application. According to the results, 1 x 10-3 and 2x10-3g trinexapac-ethyl caused significant reduction in plant height. As trinexapac-ethyl level increased, number of branches and flowers were increased accordingly most of which was under the latter treatment. Branch length and leaf number was not affected. The concentrations 1x10-3 and 2x10-3g increased chlorophyll and shoots sugars, but not on root. Similarly, soil application of Trinexapac-ethyl did not showed positive effects. In light of obtained results, foliar spray application of Trinexapac-ethyl may serve as a suitable way to produce dwarf and pot Zinnia elegans 'State fair mix'. Based on the obtained results, application of Trinexapac-ethyl as foliar application can control and reduce the height of the Zinnia elegans 'State fair mix'. [ABSTRACT FROM AUTHOR]

Medium-term in vitro plant conservation is an alternative for maintaining germplasm banks in breeding programs. The aim of this study was to evaluate the efficiency of the gibberellin inhibitors paclobutrazol (PBZ) and trinexapac-ethyl (TNE) for in vitro conservation by minimal growth in anthurium, sugarcane, and agave. For the establishment of the conservation system, shoots of the aforementioned species were taken at different concentrations (0, 1, 2, and 3 mg L−1) of PBZ and TNE. At 180 d of culture, the survival percentage, number of shoots, plant length, number of leaves, number of roots, root length, total chlorophyll content, stomatal density, and survival percentage during acclimatization were evaluated. According to the variables evaluated, the results showed that in anthurium 1 mg L−1 PBZ was the best treatment for in vitro conservation without affecting survival, while in sugarcane it was 1 mg L−1 PBZ and agave 3 mg L−1 PBZ or TNE. Survival during acclimatization was 97, 96, and 98% in anthurium, sugarcane, and agave, respectively. In this study, the gibberellin-inhibiting compounds PBZ and TNE are a low-cost alternative for in vitro conservation of anthurium, sugarcane, and agave and can be evaluated in other species. [ABSTRACT FROM AUTHOR]

Decreased stand uniformity together with reduced aesthetics and playability caused by annual bluegrass (Poa annua) intrusion in creeping bentgrass (Agrostis stolonifera) putting greens is one of the major problems that golf course superintendents face with managing newer playing surfaces. Few herbicides are registered for selective control of annual bluegrass in creeping bentgrass greens, and the risk of herbicide resistance remains an issue, thus use of plant growth regulators (PGRs) is still the primary method of annual bluegrass suppression. This study was conducted to evaluate eight PGR treatments, employed as a series of 15 consecutive, biweekly applications to suppress annual bluegrass encroachment in ‘Pure Distinction’ creeping bentgrass maintained as a golf course putting green in Los Angeles, CA. Best annual bluegrass suppression was observed with products containing flurprimidol (FP) at 0.256 lb/acre, paclobutrazol (PB) at 0.119 lb/acre, or three-way mixture of FP, trinexapac-ethyl (TE), and PB (FP+PB+TE) at 0.055, 0.014, and 0.055 lb/acre, respectively. Although all treatments caused some significant creeping bentgrass injury, which increased over time, PB at 0.119 lb/acre and FP+PB+TE at 0.055, 0.014, and 0.055 lb/acre, respectively, appeared to be safest among effective treatments. Additionally, those treatments caused significantly darker green turf, which may be desirable on putting greens. This research confirms the potential of PGR use to limit annual bluegrass infestation on creeping bentgrass greens in a Mediterranean climate and reveals the most effective treatments that could be used in a putting green maintenance program.

In 2013-2016 the possibility of combined application of herbicides with retardants in winter wheat was investigated in Institute of Soil Science and Plant Cultivation in Wrocław. Two retardants (1. chloromequate chloride, 2. trinexapac-ethyl) were used in tank mixture with fluroxypyr and florasulam + aminopyralide. The mixtures were applied on two dates: 1. at the end of tillering, 2. at the stage of 1-2 nodes (florasulam + aminopyralide) or at the stage of flag leaf (fluroxypyr). Efficacy of weed control was affected only by date of treatment. Irrespective of which herbicide-retardant combination was used, the weed suppression was the lowest on plots treated with the mixtures at a later growth stage. It was reflected in the size of grain yield received from these plots, that was comparable to untreated control. Application of the mixture of fluroxypyr with trinexapac-ethyl in winter wheat tillering and flag leaf growth stages contributed to seed uniformity decrease. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The key to high productivity of plants, especially cereals, is to control lodging of cereals. Among the derivatives of acylcyclohexadiones (ACHD), highly effective retardants have been invented, which are widely used in modern crop production to control the lodging of cereals, mainly winter wheat, spring and winter wheat, winter, spring and hybrids of barley. The mechanisms of influence of ACHD derivatives – trinexapac-ethyl and prohexadione-Ca on plants and features of their application in technologies of cultivation of cultivated plants are considered. By using a composition of ACHD derivatives with a number of agrochemicals, enhancement of retardant activity is achieved. Given the identified varietal variability of the effectiveness of the use of ACHD derivatives in cereals, it is advisable to conduct registration and post-registration studies primarily on varieties that occupy the largest sown areas in the country. The peculiarities of ACHD derivatives’ influence on stem components as the main one, along with the flag leaf, carbon pool for grain filling in the ear and possible reasons for the lack of productivity increase of grain crops due to ACHD derivatives are also considered. This class of substances continues to be widely studied in the world and remains among the most promising for the development of new agrochemicals and drugs.

Increased demand for local malting barley (Hordeum vulgare L.) for breweries and distilleries creates an opportunity for Virginia farmers. Lodging may decrease grain yield, reduce quality, and cause harvesting difficulties. Trinexapac‐ethyl (TE) is a plant growth regulator that reduces cell elongation and creates a shorter, sturdier stem. Field studies were initiated in 2017 and 2018 to test TE effects on 'Flavia' and 'Violetta' two‐rowed winter barleys at Blackstone and Holland, VA. Treatments consisted of: no TE; 7.2 fl oz TE acre−1 and 14.4 fl oz TE acre−1 at Zadoks growth stage (GS) 29; 7.2 fl oz TE acre−1 and 14.4 fl oz TE acre−1 at GS32; and 14.4 fl oz TE acre−1 equally split between GS29 and GS32 in a randomized complete block with four replications. Plant height, lodging incidence, and grain yield were measured. The effect of TE rate and timing varied, but all applications at GS32 resulted in significantly shorter plants. Plant lodging was decreased in 2019 at Blackstone by all TE applications compared to untreated. Plant height was decreased by as much as 42% in 2019 and plant injury was observed. Grain yield was decreased by all TE applications in Blackstone and GS32 and split applications in Holland in 2019, presumably due to stress preceding and following TE application. Plant growth at the time of application, forecasted weather, and cultivar susceptibility to lodging should all be considered when determining the optimal TE application rate and timing to reduce plant height without negatively impacting grain yield. Core Ideas: The plant growth regulator trinexapac‐ethyl decreased malt barley height which might lead to reduced plant lodging.Trinexapac‐ethyl application can potentially cause plant injury under adverse environmental conditions.Plant growth, weather, and cultivar should be considered when determining the optimal trinexapac‐ethyl application rate and timing. [ABSTRACT FROM AUTHOR]

Copyright of Progress in Plant Protection is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant growth regulator (PGR) applications are a common practice in managing ultradwarf bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt- Davy] putting greens. Trinexapac-ethyl (TE) is a frequently used PGR to reduce the rapid shoot growth that could reduce ball roll distance (BRD) and increase turfgrass quality. Lightweight rolling (LWR) of putting greens is a practice implemented to sustain or increase BRD. The objective of this research was to determine effects of weekly TE applications and LWR on the BRD and turfgrass quality of an ultradwarf bermudagrass putting green. Experiments were conducted in Knoxville, TN, and Starkville, MS, on a 'MiniVerde' ultradwarf bermudagrass putting green. Trinexapac-ethyl treatments included 0, 0.008, 0.024, or 0.072 lb a.i. acre-1 wk-1 and LWR five times per week. Ball roll distance was measured with a Pelzmeter in 2016 and a Stimpmeter in 2017. Turfgrass quality was visually assessed at both locations on a 1 to 9 scale, with ratings of = 6 being acceptable. At both locations, the BRDs of plots treated with 0.024 lb TE acre-1 wk-1 with LWR were only 5 inch less than 0.072 lb TE acre-1 wk-1 without LWR, a difference that is likely to be imperceptible to golfers. In addition, TE applied at 0.024 lb a.i. acre-1 wk-1 consistently yielded greater turfgrass quality than 0.072 lb TE acre-1 wk-1. Implementing LWR practices with TE application rates at 0.024 lb acre-1 wk-1 can provide similar BRD and increased turfgrass quality as TE applied at 0.072 lb acre-1 wk-1 without LWR. [ABSTRACT FROM AUTHOR]

Establishment of seedlings of economic crops is often reduced if there is not a steady supply of water. Essential oils (EO) from plants are increasingly used instead of synthetic chemicals to protect plant and animal products against biotic and abiotic stresses. We investigated priming radish seeds by soaking or by matriconditioning with synthetic or natural compounds as a means of inducing resistance to drought stress, thus maintaining crop yield. Priming radish seeds for two hours in solutions of essential oils (EO) thymol and carvacrol derived from Origanum syriacum, with “oregano natural product” (ONP; a solution of the residue remaining after EO extraction), or with the gibberellin synthesis inhibitor trinexapac ethyl (TE), was much more effective in inducing drought resistance than was matriconditioning with the same compounds in sawdust for two days. The latter treatment induced considerable fungal and bacterial infection in treated seeds if the substrate-matrix was not heat-treated beforehand. The increase in specific leaf area in plants from treated seeds was mostly consistent with an increase in leaf water content. Seed treatments with EO, ONP, and especially TE led to a three-fold increase in radish seedling survival compared with water-treated controls, when 21 day-old seedlings were irrigated after 6 days of drought. Under drought conditions, seedlings from treated seeds had a 2–3-fold increase in relative water content increased 2–3-fold, while membrane permeability decreased 20–50-fold as a result of the treatments. However, the physical benefits of the treatments often did not correlate with treatment-induced increases in physiological parameters such as pigments (chlorophyll, carotenoid, anthocyanin), pigment ratios (chlorophyll a/b, carotenoid/chlorophyll), or antioxidant activity. Seed treatments with biostimulants can be as effective as treatments with synthetic compounds in inducing drought resistance in seedlings.

Os reguladores de crescimento podem ser uma ferramenta importante no manejo da cultura do milho, principalmente em lavouras com alta tecnologia, conduzidas sob arranjo espacial adensado, em condições ambientais favoráveis e utilizando genótipos com maior desenvolvimento vegetativo. O objetivo do trabalho foi avaliar o uso de reguladores de crescimento associados a épocas de semeadura sobre características de crescimento, componentes de produção e rendimento de grãos de híbridos de milho cultivados na primeira safra. O experimento foi conduzido em campo na safra 2014/15, sob delineamento de blocos casualizados, em esquema fatorial 2x2x3, sendo duas épocas de semeadura (primeira época: 19/09/2014 e segunda época: 23/11/2014), dois híbridos de milho (2B610PW e 2B810PW) e três reguladores de crescimento (testemunha sem aplicação, trinexapac-ethyl 400 g i.a. ha-1 e clomazine 200 g i.a. ha-1, aplicados no estádio V6), com quatro repetições. Foram avaliadas as seguintes características: Altura de plantas, altura de inserção de espiga, diâmetro de colmo, índice de área foliar, número de fileiras por espiga, número de grãos por fileira, número de grãos por espiga, comprimento de espiga, diâmetro de espiga, prolificidade, peso da massa de mil grãos e produtividade de grãos. O desenvolvimento e o desempenho produtivo do milho é alterado pela interação entre as épocas de semeadura, genótipos e reguladores de crescimento. A segunda época de semeadura, não limitada pela deficiência hídrica, resulta em melhor desenvolvimento e desempenho produtivo para os dois híbridos. O híbrido 2B610 apresenta maior desempenho produtivo que o 2B810 na segunda época de semeadura. O trinexapac-ethyl e o clomazine para os dois híbridos na primeira época e para o 2B810 na segunda época favorecem a produtividade de grãos do milho. O trinexapac-ethyl apresenta redução de porte para o híbrido 2B810 na segunda época de semeadura. O crescimento e a área foliar do híbrido 2B810 é menos prejudicado pela condição restritiva da primeira época de semeadura, consequentemente há maior desempenho da massa de grãos que não permite diferenciação da produtividade entre genótipos para essa época de semeadura.

The impact of trinexapac-ethyl (TE) on salinity subjected wheat plants was evaluated via pot based experiment. The treatments applied to wheat seedlings included (Ck) control (no NaCl nor TE spray), foliar spray of TE (1.95 ml L−1), only NaCl (50 mM) and NaCl+ TE (50 mM + 1.95 ml L−1). Foliar application of TE was done seven days after imposition of salinity. Growth parameters (root length, shoot length, fresh weight, and dry weight) and photosynthetic pigments content (chlorophyll a, b, a + b and a/b), water relation (water potential, osmotic potential, turgor potential and relative water contents) as well as catalase (CAT) activity exhibited marked reduction in comparison to control. In addition, an increment was noted in organic solutes content (proline, soluble protein and soluble sugar) and enzyme activity of superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) in stressed seedlings over control seedlings. The foliar applied TE mostly enhanced growth of salt stressed seedlings, accompanied by reinforcement in photosynthetic pigments, organic solutes, and enzyme activity (SOD, CAT, POD, and APX) in comparison to stressed seedlings. It is worthy to mention that, TE has potential to enhance salt tolerance of wheat seedlings. Thus, our findings suggest that seedling treated with TE is an effective strategy that can be used to enhance salt tolerance of wheat crop. [ABSTRACT FROM AUTHOR]

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Trinexapac-ethyl (TE), a plant growth regulator (PGR) and lodging-control agent, increases seed yield in red clover (Trifolium pratense L.), but the effects of TE are unknown in crimson clover (Trifolium incarnatum L.) seed crops. The objectives of this study were to determine TE application rate and timing effects on crop canopy characteristics, seed yield, and seed yield components of crimson clover. On-farm trials were conducted at two locations (Banks and St. Paul, OR) in 2012 and 2013 and at the Hyslop Research Farm near Corvallis, OR, in 2015 and 2016. Treatments were TE PGR application rates (0, 105, 140, 210, 280, 420, and 560 g a.i. ha.1) and two application timings (stem elongation, Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie [BBCH] 32; inflorescence emergence, BBCH 51). Application of TE PGR reduced height of the seed crop canopy. Seed yield was increased in 2012 and 2013 with rates .280 g TE ha-1 when applied at the BBCH 32 timing. Seed yield increases attributable to TE ranged from 12 to 36%. However, no effects of TE application on seed yield were observed in 2015 and 2016, likely as a result of dry and warm spring weather. Seed yield increases in 2012 and 2013 were a result of TE-induced increases in seeds m.2. Seed weight was reduced by TE application, and these reductions were inversely proportional to TE rate. Seed yield responses in crimson clover to TE PGR varied across years and locations, with seed yield increases occurring in wet and cool spring weather conditions. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant growth regulators (PGRs) and irrigation affect seed yield of red clover (Trifolium pretense L.). However, the effects of these factors on physiological maturity (PM), harvest maturity (HM), and seed quality are unknown. Therefore, the objectives of this study were to determine the effects of trinexapac-ethyl (TE) PGR and irrigation on PM, HM, and seed viability and vigor on the most common red clover variety in Oregon over 2 yr. Five TE rates, ranging from 0 to 700 g a.i. ha-1, were applied at stem elongation and bud emergence stages. Irrigation was applied at the first flowering stage. Physiological and visual indicators were recorded to determine PM and HM. Standard germination (SG), tetrazolium (TZ) and cold (CT) tests were conducted to evaluate seed quality at weekly intervals starting from seed formation until HM. Irrigation resulted in a 4-d delay in PM compared to the non-irrigated treatment, but TE applications did not affect timing of seed maturation. At PM, flower heads contained light brown petals and brownish-green sepals, whereas seeds were pale green to pale yellow. At HM, heads contained dark brown petals and sepals, whereas seeds ranged from yellow to yellow-dark grayish purple. Seed dry weight did not change from PM to HM. Seed moisture content at PM ranged from 340 to 540 g kg-1 and decreased to below 140 g kg-1 at HM. At HM, seeds reached maximum quality as viability ranged from 92 to 98% by TZ and SG, and vigor ranged from 90 to 94% by CT. [ABSTRACT FROM AUTHOR]

Bermudagrass [Cynodon dactylon (L.) Pers.] is a perennial grass and has been long used as a medicinal herb in Iranian traditional medicine to treat varied ailments. Different parts of bermudagrass such as leaves, stolons, rhizomes and culms are rich sources of metabolites such as proteins, carbohydrates, mineral constituents, β-sitosterol, flavonoids, alkaloids, glycosides and triterpenoides. Growth regulators change plant physiological processes such as phytochemical accumulation. Paclobutrazol (PBZ) and Trinexapac-ethyl (TE) are two popular growth retardant that inhibit gibberellic acid (GA) biosynthesis. This greenhouse experiment was conducted to determine effects of TE and PBZ application on bermudagrass growth and phytochemical content. Paclobutrazol was applied twice at four weeks intervals at 0, 1, 2, 3 and 4 g a.i. (active ingredient) /100 m2 and TE treatments (0, 0.25, 0.5, 0.75 and 1 g a.i. /100 m2) were applied biweekly over 8 weeks period. Shoot and root growth, were decreased with increasing PBZ and TE application rates except for TE0.5 treatments that showed higher root growth than control plants. Chlorophyll, Total non-structural carbohydrates, soluble flavonoids and protein content were increased with increasing PBZ and TE application rates unless TE1 treatment that exhibited lower total non-structural carbohydrates (TNC) content than untreated plants. The results suggest that TEand PBZ treatments were beneficial for bermudagrass phytochemical content enhancement. However, puclobutrazol application, because of higher phytotoxity than trinexapac ethyl (lower plant quality and sever shoot depression), seems to be less effective in raising medicinal properties.

High rates of nitrogen (N) increase plant growth, which can result in lodging. To avoid excessive growth of plants, plant growth regulators (PGRs), which cause internode length reduction, can be used. In this study, our objective was to evaluate the N nutritional status, growth, and yield of irrigated wheat as parameters using variable rates of nitrogen and growth regulator. Two experiments were conducted in Rio Paranaíba – MG in 2011 and 2012 using the BRS 264 cultivar. The treatments consisted of two concentrations of N (50 and 110 kg ha-1 as urea) and five concentrations of the growth regulator trinexapac-ethyl (0, 0.2, 0.4, 0.6, and 0.8 L ha-1 of Moddus® containing 25% w/v of trinexapac-ethyl). Each plot consisted of 20 rows of wheat spaced 0.17 m, six meters in length. We evaluated plant height, shoot dry matter accumulation, thousand-grain weight, number of grains per spike, yield, leaf N content in the index leaf and grain, amount of N uptake and export, and lodging index. The PGR resulted in a linear decrease in plant height and shoot dry matter production. However, the rates of the growth regulator did not affect productivity. The rates of N influenced the yield only in 2011.

Core Ideas: Trinexapac‐ethyl (TE) is a common plant growth regulator used in turfgrass systems.The effects of TE on herbicide efficacy to control smooth crabgrass were unknown.Mixing TE with postemergence herbicides did not affect smooth crabgrass control. [ABSTRACT FROM AUTHOR]

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Lithuania, and co‐rapporteur Member State Latvia for the pesticide active substance trinexapac and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of trinexapac as a plant growth regulator on barley (winter and spring) and wheat (winter). MRLs were assessed in rye. The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. The confirmatory data following the review of existing MRLs according to Article 12 of Regulation (EC) No 396/2005 were also assessed under this conclusion. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

ABSTRACT The objective of this study was to evaluate the effect of growth reducer and nitrogen fertilization on morphological variables, SPAD index, radiation interception, and grain yield of three cultivars of wheat. The experimental design was a randomized block in factorial scheme 3x5x2, with three cultivars (Mestre, Iguaçú and Itaipú), five nitrogen doses (0, 40, 80, 120, 160 Kg ha-1), and application or no application of a growth reducer, with three replications. The following characteristics were evaluated: plant height, SPAD index, leaf area index (LAI), Global Radiation Interception (GRI) and grain yield. The Tukey test (p < 0.05) was used for the comparison between the means of cultivar and growth reducer factors, and for a regression analysis to evaluate N levels. Increasing the dose of nitrogen promotes an increase in LAI of plants of wheat crops differently among cultivars, which leads to a greater degree of global radiation interception. At doses higher or equal to 120 Kg ha-1 of nitrogen, there are significant differences in grain yield between treatments with and without the application of the growth reducer. The significant interaction between growth reducer and nitrogen dose, showed that applications of growth reducer increase the GRI at doses above and below 80 Kg ha-1 of nitrogen. Nitrogen rates of 138 and 109 Kg ha-1 are responsible for maximum grain yields of wheat, which is 4235 and 3787 Kg ha-1 with and without the use of growth reducer, respectively.

Drought Stress is one of the most important limiting factors in plants growth and development. Growth regulator, Trinexapac-ethyl, might improve drought stress resistance via reducing stem growth and improving osmotic adjustments. In present study Trinexapac-ethyl effect on some tall fescue var Rebel physiological and morphological traits under irrigation free conditions was studied. So, an experiment was carried out as factorial in completely randomized design in three replicates in Research Farm of Isfahan University of Technology in 2011 - 2012. Treatments involved three growth regulator levels of Trinexapac-ethyl (0, 250 and 500 g.h-1) and two drought stresse levels (normal irrigation and without irrigation). Leaf growth rate, leaf tissue, leaf color, relative water content, electrolyte leakage, proline level, above ground fresh and dry weight, root penetration and effective depth were measured. Results showed that Trinexapac-ethyl and drought stress reduced growth rate, above ground organs fresh and dry weight. Concentrations of 250 and 500 g/ha Trinexapac-ethyl decreased plant height by 19.48 and 22.24 percent respectively. Unlike drought stress, concentrations of 250 and 500 g/h Trinexapac-ethyl increased tissues color by 11.62 and 13.08 percent respectively. Also, relative water content and electrolyte leakage increased and decreased respectively but proline content of the Trinexapac-ethyl treated plants was not affected significantly. Drought stress reduced relative water content significantly and increased electrolyte leakage and proline content. Application of Trinexapac-ethyl did not significantly affect root traits but it increased penetration and effective depth under stress condition. Levels of 250 and 500 g.ha-1 Trinexapac-ethyl showed significant differences in relative water content and no significant differences in other characteristics. It was found that tall fescue var Rebel is drought resistant and Trinexapac-ethyl can be used to induce drought stress resistance.

In order to evaluate the effect of trinexapac ethyl concentrations (0, 250 and 500 g/h) and traffic stress (traffic and non traffic) treatments on wheat grass physiological and morphological traits, an experiment was conducted on research farm of Isfahan University of Technology in 2011 - 2012 as factorial in completely randomized designs with three replications. The studied traits involved plant height and plant density, shoot dry weight and fresh weights, tillering, chlorophyll level, roots and shoot dissolved carbohydrates. Results showed that Trinexapac ethyl reduced plant height, fresh weight and dry weight of cut parts significantly. Application of 250 and 500 g/h Trinexapac ethyl decreased plant height by 21.23 percent and 31.85 percent respectively. Application of Trinexapac ethyl improved plant height, tillering and chlorophyll level. In contrast, chlorophyll level was decreased substantially under traffic treatment and this treatment did not affect wheat grass density and tillering significantly. Under 500 g/h Trinexapac ethyl treatment, tillering was increased by 36 percent compared with under control condition one. Results showed that Trinexapac ethyl application and traffic increased dissolved carbohydrates of root and shoot significantly. As a result, it was found that wheat grass is a traffic resistant plant and it seems that the use of Trinexapac ethyl increases plant resistance to traffic stress

Soil surfactants and plant growth regulators (PGR) have shown potential to lower irrigation requirements and increase turfgrass quality under drought conditions. A study was conducted from 2014 to 2016 to investigate the soil surfactant Revolution, (modi- fied methyl capped block copolymer [Aquatrols, Paulsboro, NJ]), or the plant growth regulator 'PrimoMaxx' (A.I. trinexapac-ethyl [4-(cyclopropylhydroxymethylene)-3,5-dioxocyclohexanecarboxylic acid]) (Syngenta, Basel, Switzerland), or a combination of both on percent green coverage, turfgrass color, quality, soil volumetric water content (VWC) and uniformity on Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamments) and irrigated at either 80%, 65%, or 50% of reference evapotranspiration for short grass (ETOS). With the exception of plots irrigated at 50% ETos in 2015, bermudagrass receiving trinexapac-ethyl (TE) either in combination with Revolution or alone exhibited darker green color when compared to untreated controls at all irrigation levels throughout the research period. At 50% ETos, plots treated with any of the three chemical treatments had greater quality (with 1 = worst, 9 = best) than control plots from July to September, with quality ratings of 6 or greater from June to August. Whereas VWC was not consistently enhanced by all treatment combinations, applications of Revolution, TE, and the combination of both resulted in increased VWC uniformity and greater irrigation use efficiency. Our results suggest that by using a surfactant, a PGR, or both, bermudagrass quality can be maintained with 15 to 30% less irrigation water than the optimal rate (80% ETos) without a reduction in color or quality. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the physiological quality of white oat seeds cultivated under different topdressing N levels combined with the plant growth retardant trinexapac-ethyl in two growing environments. The experiments were carried out in Londrina and Mauá da Serra Municipalities (PR, Brazil) with the cultivar 'IPR Afrodite'. The experimental design was in randomized blocks, in a 4x2 factorial arrangement, with four replications. Treatments consisted of four N levels (0, 30, 60, and 90 kg.ha-1) combined or not with the plant growth retardant. Seed yield, 1000-seed weight, germination, first germination count, seedling length, seedling dry matter, accelerated aging, electrical conductivity, emergence speed index, and seedling emergence in sand were evaluated. Data were submitted to the analysis of variance and then to the F test and regression analysis up to the second degree (p=0.05). The application of the plant growth retardant and N topdressing led to an increase in seed productivity in Mauá da Serra. N fertilization reduced seed quality, but this effect can be minimized, not observed or overlapped by the positive effect of the plant growth retardant. Such an effect depends on environmental characteristics and it was not observed in Londrina. [ABSTRACT FROM AUTHOR]

Intermediate wheatgrass (Thinopyrum intermedium; IWG), a new perennial grain crop, has the potential to provide ecosystem services while producing food-grade grain; however, productivity is currently limited by high rates of lodging. Trinexapacethyl (TE) and prohexadione-calcium (PC) are widely used plant growth regulators (PGRs) for mitigating lodging and improving seed yield in other grass crops. Our objectives were to determine the effects of the PGRs PC and TE, PGR application rate, and nitrogen (N) fertilizer rate (0, 40, 80 kg N ha-1) on IWG lodging, height, and grain and biomass yields. Experiments were initiated in first- and third-year stands at St. Paul and Rosemount, MN. Few effects of PC on IWG height, lodging, or yields were observed, while TE consistently reduced plant height by 10 to 20% and lodging by up to 20% in a year with high lodging risk. Application of TE to IWG at the recommended rate (437 g a.i. ha-1) or higher rates increased grain yields by 65 to 100% when lodging incidence was high, but did not affect grain yields in years with lower lodging risk. While a negative correlation between lodging and grain yields was observed, nitrogen fertilizer affected IWG grain and biomass yields in only one of five site-years, and there was no interaction between N fertilizer and PGR effects on IWG. Nonetheless, the PGR TE demonstrated the potential to reduce plant height and lodging, thereby increasing IWG yield potential. [ABSTRACT FROM AUTHOR]

The results were presented with three new ripeners (DP 98 (PO3), Moddus (Trinexapac-ethil CE 250 y Biqticon SC) in three fields, the evaluation was carried out between 3 and 5 weeks before harvest, t pol ha-1 was calculated considering the percentage of pol in cane of The last week evaluated in each test and field performance, to all treatments based in sugar production ha-1, cost-benefit analysis was performed. Regrowth analysis was performed 50 days after the cut, these results were subjected to fixed effects variance analysis, the percentage of increase with respect to the control was also determined. As a result, the DP-98 (PO3) products and the glyphosate + DP-98 (Round-up CS48 + PO3) mixture reached values higher than the control in the sugar content from the first week of evaluation, whereas Glyphosate exceeded it from the third week, the Cost - benefit ratio was in favor of Glyphosate. The Moddus CE 250 had a lower behavior than the control in the percentage of pol in cane during the five weeks that was evaluated, what could be given that its recommendation is from the sixth week. There was an increase in the variable analyzed from the first week in favor of Biqticon, the cost - benefit ratio for this product was 1.09, higher than glyphosate and the control. Glyphosate treatment increased the number of dead strains in the regrowth by 9 %. [ABSTRACT FROM AUTHOR]

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Lithuania, and co-rapporteur Member State Latvia for the pesticide active substance trinexapac and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of trinexapac as a plant growth regulator on barley (winter and spring) and wheat (winter). MRLs were assessed in rye. The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. The confirmatory data following the review of existing MRLs according to Article 12 of Regulation (EC) No 396/2005 were also assessed under this conclusion. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. [ABSTRACT FROM AUTHOR]

Copyright of Arquivo Brasileiro de Medicina Veterinaria e Zootecnia is the property of Universidade Federal de Minas Gerais, Escola de Veterinaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soft red winter wheat (SRWW) is an important crop in the mid-Atlantic. The use of growth regulators such as trinexapac-ethyl (TE) applied with nitrogen applications at pseudo-stem erection [Zadocks (ZGS) 30] has gained more interest in the region as a means to reduce lodging and potentially improve yields. Fungicide use has also increased, with many growers applying fungicides at ZGS 30 and again at ZGS 37 or ZGS 60. The safety and utility of TE in SRWW production systems, used alone or in combination with fungicides, is unknown. We evaluated the utility and safety of TE, applied alone, tank mixed with a fungicide at ZGS 30, and in combination with a foliar fungicide at ZGS 37 or ZGS 60 for utility and safety in mid-Atlantic SRWW. Three replicated field experiments were conducted over two growing seasons in Delaware, and yield, test weight, and disease severity on the flag leaf, were assessed. No phytotoxicity was noted in any of the TE or TE x fungicide treatments tested. TE applied alone reduced plant height by nearly 7 cm, but the application of fungicide at ZGS 37 or 60 slightly negated this effect. No lodging was observed. The addition of a fungicide at ZGS 30 followed by Prosaro (prothioconazole + tebuconazole) at ZGS 60 resulted in the greatest yields and test weights. All fungicide programs significantly reduced leaf blotch complex on the flag leaves relative to untreated controls; however, no difference was detected between ZGS 37 and ZGS 60 treatments. These results indicate that TE can be used safely in SRWW production when applied alone or when tank mixed with a fungicide; however, the effect on plant height reduction and potential impact on lodging may be reduced in situations where fungicides are used. [ABSTRACT FROM AUTHOR]

Eucalyptus plants are sensitive to abiotic stresses in their initial growth, and nutritional deficiency is one of the most recurrent among them. Trinexapac-ethyl, which is a plant growth regulator, can positively affect eucalyptus, a response known as hormesis, possibly providing plants with greater tolerance to stress. The objective of this study was to evaluate the effect of trinexapac-ethyl at two application times, before planting (BP) or after planting (AP), in Eucalyptus urophylla under conditions of nutritional deficiency (NPK). Two experiments (one for each application time) were conducted simultaneously during 81 days after planting of eucalyptus in 15 L pots. The treatments consisted of three doses of trinexapac-ethyl (0, 30, and 60 g a.i.·ha−1) and four variations of nutrient supply: complete solution (NPK) and solutions without nitrogen (−N), without phosphorus (−P), and without potassium (−K). The variables of gas exchange, growth, and dry matter were evaluated. For both application times, trinexapac-ethyl had a positive effect on the root-shoot ratio of plants grown in −N and also positively affected some eucalyptus photosynthetic characteristics. In the AP application, the compound provided gains in height and dry matter, regardless of the nutrient supply. Under phosphorus deficiency, trinexapac-ethyl provided gains in total dry matter (BP) and leaf area (AP). [ABSTRACT FROM AUTHOR]

Improvement on yield potential of plants by crop management is the main research challenge due to the growing of food demand worldwide. The objective of this work was to study physiological and morphological traits and its relationship with yield components and yield of wheat as affected by sowing densities and plant growth regulators. The experimental design was a split-plot design with four replications. The plots were consisted by four sowing densities (30, 50 70 and 90 plants m-1) and the subplots were consisted by plant growth regulators [control, (IBA+GA+KT), Trinexapac-Ethyl e (IBA+GA+KT) + Trinexapac-Ethyl]. Dry matter accumulation, plant height, source-sink distance, gas exchange and yield were determined. Trinexapac-Ethyl application resulted in decreasing of plant height, source-sink distance and flag leaf length; however, the grain yield was not affected. The number of plants per unit area affected dry matter accumulation. Higher dry matter accumulation showed direct relationship with yield and yield components in lower plant densities.

Tillering capacity of wheat is highly influenced by environmental conditions and management practices. This research had as objective to evaluate tiller emission, survival and contribution to grain final yield affected by increasing sowing densities and growth regulators application in wheat. The experiment was conducted under completely randomized block design, with subdivided plots and four replications. Treatments consisted of four plant densities (30, 50, 70 and 90 plants m-1) combined with the application of growth regulators [control, (IBA+GA+KT), Trinexapac-Ethyl and (IBA+GA+KT) + Trinexapac- Ethyl]. Tiller emission, contribution to dry matter accumulation and grain yield, survival and yield potential in relation to the main stem were evaluated, as well as yield components and grain final yield. The application plant growth regulators did not affect tiller emission or any other yield parameters related to the main stem. Increasing plant densities reduced tiller emission and dry matter accumulation, which led to lower tiller contribution and yield potential. Reduced plant densities increased grain yield due to higher grain number and mass per ear, making up for lower number of ears per area.

Establishment of seedlings of economic crops is often reduced if there is not a steady supply of water. Essential oils (EO) from plants are increasingly used instead of synthetic chemicals to protect plant and animal products against biotic and abiotic stresses. We investigated priming radish seeds by soaking or by matriconditioning with synthetic or natural compounds as a means of inducing resistance to drought stress, thus maintaining crop yield. Priming radish seeds for two hours in solutions of essential oils (EO) thymol and carvacrol derived from Origanum syriacum, with "oregano natural product" (ONP; a solution of the residue remaining after EO extraction), or with the gibberellin synthesis inhibitor trinexapac ethyl (TE), was much more effective in inducing drought resistance than was matriconditioning with the same compounds in sawdust for two days. The latter treatment induced considerable fungal and bacterial infection in treated seeds if the substrate-matrix was not heat-treated beforehand. The increase in specific leaf area in plants from treated seeds was mostly consistent with an increase in leaf water content. Seed treatments with EO, ONP, and especially TE led to a three-fold increase in radish seedling survival compared with water-treated controls, when 21 day-old seedlings were irrigated after 6 days of drought. Under drought conditions, seedlings from treated seeds had a 2-3-fold increase in relative water content increased 2-3-fold, while membrane permeability decreased 20-50-fold as a result of the treatments. However, the physical benefits of the treatments often did not correlate with treatment-induced increases in physiological parameters such as pigments (chlorophyll, carotenoid, anthocyanin), pigment ratios (chlorophyll a/b, carotenoid/chlorophyll), or antioxidant activity. Seed treatments with biostimulants can be as effective as treatments with synthetic compounds in inducing drought resistance in seedlings. [ABSTRACT FROM AUTHOR]

The development of cultivars ‘TifGrand’ and ‘Celebration’ has shown potential increases in shade tolerance compared to previous industry standards of bermudagrass ( Cynodon spp.). Based on the literature, further improvements in shade tolerance can be attained through changes in nitrogen fertility rates, mowing heights, and the application of plant growth regulators. In this study, two South African hybrid ( Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy) bermudagrass accessions (‘WIN10F’ and ‘STIL03’) and three standard cultivars (Celebration, Tifgrand, and ‘Tifway’) were compared for their ability to persist under 63% shade, two mowing heights, two trinexapac-ethyl (TE) treatments, and two nitrogen fertility rates. The experimental design was a strip-strip-split plot and digital image analysis was used to measure percent turfgrass cover, percent turfgrass spread after cup-cutter removal, and percent turfgrass re-growth after divot formation. Turf quality was measured using the normalized difference vegetation index (NDVI). Differences among genotypes, TE treatments, and mowing heights were observed across all response variables in 2014 and 2015. Differences in fertility treatments were observed in NDVI, percent turfgrass growth, and percent turfgrass recovery within and across years. Significant differences were observed for the interactions between entry by plant growth regulator (PGR) treatments, entry by mowing height, and mowing height by PGR. These results suggest shade management recommendations should be dependent on genotype and site-specific considerations. The development and implementation of specific management plans for certain bermudagrass varieties will contribute to the more widespread use of Cynodon spp. in shaded environments. [ABSTRACT FROM AUTHOR]

The positive effects of trinexapac-ethyl (TE) on turfgrass growth and tolerance to various types of stress could promote its use in low-input maintenance turfgrasses to reduce the expense associated with mowing. However, there is a general lack of information about TE effects in low maintenance turfgrasses, and especially when used in transition zone turfgrass mixtures. The objective of this study was to evaluate the response of three inter-specific turfgrass mixtures to three different application rates of TE under low maintenance conditions. A 2-year field study was conducted from April 2006 to July 2008 at the Agricultural Experimental Farm of the University of Padova (northern Italy, 45°20′N, 11°57′E, elevation 8 m). Visual turfgrass quality (1–9 scale) and clippings biomass production of three mixtures were evaluated seasonally under four TE treatments with rates representing 0, 0.5, 1.0 or 1.5x the rates indicated on label instructions. Based on both visual quality and biomass production, turfgrass responded differently to TE application depending on dominant species in the mixture. Furthermore, our results suggested that changes over time in turfgrass botanical composition influence visual quality and biomass production through the experimental period. The main effect of TE treatments occurred in biomass production while the effect on turfgrass quality was mainly associated with the two highest TE rates. Application at a rate lower than the labeled seems to be enough for reducing biomass production without affecting turfgrass quality or even, in some seasons, improving it. Finally, we found that the effect of TE seems to weaken over time as turfgrass maturity advances. [ABSTRACT FROM AUTHOR]

First-year crops of diploid perennial ryegrass (cvs. Meridian, Bronsyn and Grasslands Impact) were sown on 1 April and 14 May 2008. Applications of trinexapac ethyl ( TE) plant growth regulator at 0, 200 and 400 g a.i. ha−1 were used to shorten stems to examine the impact of seed growth. Seed filling followed a consistent sigmoidal growth pattern with a lag phase of 127°C days, and linear duration of 390°C days. Time to 95% of final seed weight was 517°C days. Seed yield increases from TE were from higher numbers of first-grade seeds m−2, achieved by a higher rate of seed filling during the linear phase of 0·115 mg per °C day per spike. For all cultivars, the maximum stem dry weight occurred at 310-400°C days post-anthesis, which suggest the stem was a strong sink. As seeds developed, their demand for assimilate increased and they drew more from the stem. At harvest, stem weights from TE treatments were 25% heavier than at anthesis, while untreated 'Bronsyn' and 'Grasslands Impact' stems were similar to those at anthesis. Thus, stems treated with TE contributed assimilates to increase seed yield but were still a net sink with assimilates in the stem at harvest. Trinexapac ethyl rate induced an inverse relationship between seed yield and stem height. This showed that competition for assimilate between stems and growing seeds limited the seed yield. Management or genetic factors that reduce stem height are likely to increase seed yields of perennial ryegrass. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Drought stress is the major limiting factor which affects turfgrass management in area with restricted rainfall or irrigation water supply. Trinexapac ethyl (TE), Paclobutrazol (PAC) and Abscisic acid (ABA) are three plant growth regulators (PGRs) that are commonly used on turf species for increasing their tolerance to different environmental stresses such as drought. However, little is known about the impact of PGRs on stress tolerance of Iranian Perennial ryegrass ( Lolium perenne ). The present study was conducted to examine the visual and physiological changes of Iranian Perennial ryegrass in response to foliar application of TE, PAC, and ABA under drought stress conditions. According to the obtained results, application of all three PGRs considerably restored visual quality of drought exposed plants. TE treatment increased chlorophyll content, proline content and resulted in less malondialdehyde (MDA) in drought stressed Perennial ryegrass. Application of all PGRs enhanced the relative water content (RWC) and decreased the electrolyte leakage (EL) and Hydrogen peroxide contents (H 2 O 2 content) of plants under drought stress, though the impact of TE was more pronounced. Throughout the experiment, TE- and ABA-treated plant showed greater soluble sugar (SSC) content as compared to the control. Antioxidant enzymes activities of drought exposed plants were considerably increased by PGRs application. Catalase (CAT) and Superoxide dismutase (SOD) activities were greater in TE-treated grasses followed by PAC-treated plants. Ascorbate peroxidase (APX) and peroxidase (POD) activities were significantly enhanced by TE and ABA application. The results of the present investigation suggest that application of TE, ABA and PAC enhances drought tolerance in Perennial ryegrass. TE, PAC and ABA were all effective in mitigating physiological damages resulting from drought stress, however the beneficial effects of TE were more pronounced. The result obtained of real time-PCR suggested that regulation of CAT , APX , POD and SOD genes expression at translational levels highly depended on the application of TE, PAC and ABA. Also, the results showed that deletion mutation in SOD and POD genes were not leading to enzyme inactivation. [ABSTRACT FROM AUTHOR]