Search

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.

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.

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.

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.

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.

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.

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

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.

This trial aimed to evaluate the effect of sequential applications of different plant regulators over growth and flower rachis emission of 'Meyer' zoysiagrass (Zoysia japonica). The study was conducted on 15-month old green turfgrass under a randomized complete block design with four replications. The following plant regulator and doses were tested: trinexapac-ethyl (113+113, 226+113, 226+226, 452+113, 452+226, 452+452, 678+339 e 904+452 g a.i./ha-1), prohexadione-calcium (100+100 e 200+200 g a.i. ha-1) and bispyribac-sodium (40+40 e 60+60 g a.i. ha-1), as well as an untreated control. The turfgrass was mowed again at 3.0 cm aboveground and the second plant regulator was applied when 'Meyer' zoysiagrass was between 5.0 and 6.0 cm high. The effect of the treatments was visually rated for visual injury, plant height, height and number of flower rachis, and total dry mass production of clippings. Only bispyribac-sodium had visual symptoms of injury on 'Meyer' zoysiagrass, and no intoxication was observed at 28 days after the second application (DAAB). The sequential applications of trinexapac-ethyl, prohexadione-calcium and bispyribac-sodium reduced by more than 80% the total clipping dry mass produced by 'Meyer' zoysiagrass. All the plant regulators tested also showed promising results in reducing the height and emission of rachis, especially when trinexapac-ethyl was applied at the doses 452+452, 678+339 and 904+452 g a.i. ha-1. 'Meyer' zoysiagrass turfgrass can be handled with the sequential application of a plant regulator, which reduces the need for mowing over a period up to 110 days after the application of the second plant regulator, and it also avoids deleterious visual effects over turfgrass.

A fim de avaliar o efeito do regulador de crescimento trinexapac-ethyl em diferentes doses e épocas de aplicação em dois híbridos de milho, instalaram-se dois experimentos em Ponta Grossa, PR, Brasil, no ano agrícola de 2010/11. O delineamento experimental foi o de blocos ao acaso, em esquema fatorial 4 x 4 (doses x épocas de aplicação), com quatro repetições. Os tratamentos constaram da aplicação do trinexapac-ethyl (Moddus®) nas doses de 0,0, 187,5, 375,0 e 562,5 g ha-1 nos estádios V2, V4, V6 e V8 do milho, nos híbridos Status TL e Maximus TLTG. Avaliaram-se características agronômicas, componentes de produção e produtividade. A época de aplicação do trinexapac-ethyl não afetou características agronômicas e a produtividade dos dois híbridos de milho. Em relação à dose do regulador, somente o Maximus TLTG mostrou aumento da largura e diminuição do comprimento das folhas com o incremento da dose do produto, sem efeitos substanciais nos componentes da produção e na produtividade. Os resultados mostraram pouca resposta dos híbridos avaliados à dose e época de aplicação do trinexapac-ethyl; ao contrário do trigo, o uso na cultura deve ser mais bem avaliado, especialmente em relação à dose do produto e à reação de híbridos.Aiming to evaluate the effect of different rates and application times of the growth regulator trinexapac-ethyl on two corn hybrids, two experiments were carried out in Ponta Grossa, PR, Brazil, in the agricultural year 2010/2011. The experimental design was arranged in randomized blocks in a factorial scheme 4 x 4 (rates x time) with four replications. Treatments consisted of application of trinexapac-ethyl (Moddus®) at the rates of 0.0, 187.5, 375.0, and 562.5 g ha-1 and corn stages V2, V4, V6 and V8 of the hybrids Status TL and Maximus TL TG. The agronomic traits yield and yield components were evaluated. Time of application of trinexapac-ethyl did not affect yield and agronomic characteristics of the two corn hybrids. In relation to the regulator rate, only Maximus TL TG responded to increased product rate, with increased leaf width and length, without substantial effects on yield and yield components. The hybrids showed little dose response to rate and time of application of trinexapac-ethyl; unlike wheat, the use of the culture should be further evaluated, especially in relation to the amount of the product and the reaction of the hybrids.

The objective of this study was to evaluate growth regulators with purpose of reducing the size of heliconia ‘Red Opal’ potted plants. The experiment was carried out in randomized block design with five treatments (trinexapac-ethyl and paclobutrazol at rates of 37.5 and 75.0 mg of active ingredient per pot and control without growth regulator) and five replicates. The treatments were applied 40 days after planting the rhizomes in pots filled with soil. Thirty and 150 days after the growth regulator application, plant height, number of leaves and shoots, petioles length and leaf area were evaluated. One year after planting the rhizomes in pots the number of inflorescence and leaves (leaves, sheathing leaf bases and inflorescences) and rhizomes (rhizomes and roots) dry mass were determined. Trinexapac-ethyl had no differences compared to the control in any of the variables evaluated. Paclobutrazol proved effective in reducing plant height, leaf area and petiole length and increase in number of leaves and shoots but the effect was temporary. Also, it did not affect the inflorescences production and leaves and rhizomes dry mass. Paclobutrazol is efficient to promote height reduction and to increase the number of shoots in heliconia ‘Red Opal’ potted plants without affect the inflorescence formation but its effects is temporary.

Abstract In accordance with Article 6 of Regulation (EC) No 396/2005, the evaluating Member State (EMS) the Netherlands received an application from Syngenta Crop Protection BV to set the import tolerance for the active substance trinexapac in poppy seed imported from Australia. The Netherlands drafted an evaluation report in accordance with Article 8 of Regulation (EC) No 396/2005, which was submitted to the European Commission and forwarded to EFSA. According to EFSA, the data are sufficient to derive a maximum residue level (MRL) proposal of 7 mg/kg for poppy seed. Adequate analytical enforcement methods are available to control the residues of trinexapac on the commodity under consideration. Based on the risk assessment results, EFSA concludes that the expected residues of trinexapac on poppy seed will not result in a consumer exposure exceeding the toxicological reference value and therefore are unlikely to pose a consumer health risk.

Influence of growth regulators chlormequat chloride, ethephon, trinexapac-ethyl, and a combination of chlormequat chloride and ethephon on decreasing sunflower height was examined in the years 2006-2009. Height was reduced by as much as 63 cm by double application of chlormequat chloride (915 g/ha) + ethephon (465 g/ha) at early and later growth stage (BBCH 32 and 50). Trinexapac-ethyl (375 g/ha) did not affect the height. One-time application of chlormequat chloride (1440-2160 g/ha), chlormequat chloride (458 g/ha) + ethephon (233 g/ha) (BBCH 30 or 50), or ethephon (480 g/ha) (BBCH 30) was sufficient for a ca 30 cm reduction during flowering, but this effect did not last until harvest. With double application (BBCH 30 and 50), reduction lasted until harvest. For ethephon (480 g/ha), application at BBCH 50 reduced height by as much as 35 cm and lasted until harvest. Combining a lower rate of ethephon with ammonium sulfate was effectively equivalent to using a full rate. Flower head diameter at maturity showed no significant negative influence compared to the control. In 2008 and 2009, a delay in flowering onset was observed after applying growth regulators.

Plant lodging in wheat has been controlled through growth retardants. However, there is lack of information on the effect of these products on the physiological quality of seeds. The objective of this study was to evaluate the physiological quality of wheat seeds obtained under different rates and application times of three growth retardants. The trial was carried out in Viçosa-MG, from May to September 2005, in a factorial and hierarchical scheme, in randomized block design with four replications and a control treatment. The treatments consisted of 500, 1000 and 1500g ha-1 of chlormequat; 40, 80 and 120g ha-1 of paclobutrazol and 62.5, 125 and 187.5g ha-1 of trinexapac-ethyl applied at the 6 or 8 growth stage based on the scale of Feeks and Large, and a control treatment without growth retardant application. Leaf application of growth retardants as chlormequat, paclobutrazol and trinexapac-ethyl did not affect the germination and vigor of wheat seeds.O acamamento de plantas na cultura do trigo tem sido controlado com o uso de redutores de crescimento. No entanto, há carência de informações sobre o efeito desses produtos na qualidade fisiológica de sementes. O objetivo deste estudo foi avaliar a qualidade fisiológica das sementes de trigo obtidas sob efeito de doses e épocas de aplicação de três redutores de crescimento. O experimento, conduzido em Viçosa, Minas Gerais, entre maio e setembro de 2005, foi instalado com tratamentos em esquema fatorial e hierárquico com uma testemunha, no delineamento em blocos casualizados, com quatro repetições. Os tratamentos foram 500, 1000 e 1500g ha-1 de clormequat; 40, 80 e 120g ha-1 de paclobutrazol e 62,5, 125 e 187,5g ha-1 de trinexapac-etil aplicados no estádio 6 ou 8 da escala Feeks e Large, mais uma testemunha sem aplicação de redutor. A aplicação foliar dos redutores de crescimento clormequat, paclobutrazol e trinexapac-etil não afeta a germinação e o vigor das sementes de trigo.

A mangicultura no semiárido brasileiro destaca-se pelos altos rendimentos, pela qualidade do fruto produzido e pela possibilidade de produção durante todo o ano, devido a condições climáticas e tecnologias para o manejo do crescimento vegetativo e da floração, com uso da irrigação, podas e retardantes vegetais. O paclobutrazol aplicado ao solo é utilizado no manejo da produção da mangueira na maioria dos pomares. Entretanto, há a necessidade de identificar retardantes vegetais que possam ser aplicados via foliar, de forma a minimizar os resíduos no solo e evitar o uso de quantidades inadequadas ao longo dos anos. Assim, este trabalho teve como objetivo avaliar retardantes vegetais aplicados via foliar na inibição do crescimento vegetativo de mudas de mangueira 'Tommy Atkins'. Prohexadione-Ca, etil-trinexapac e cloreto de chlormequat, aplicados via foliar, na dose de 1g i.a. planta-1, regulam o crescimento de ramos vegetativos, mas apresentam tempo diferenciado de atividade nas mudas, sendo 20 dias para prohexadione-Ca, 30 dias para cloreto de chlormequat e 45 dias para etil-trinexapac, nas condições em que o experimento foi conduzido.The mango in the Brazilian semi-arid region stands out in the national scenario due to high yields and fruit quality, as well as to the possibility of all-year production due to climatic conditions and technologies which allow the management of plant growth and flowering through irrigation, pruning and use of plant growth regulators. Paclobutrazol applied to the soil is used for the production management of mangoes in most of the orchards. However, it is necessary to identify plant growth regulators which might be applied to the leaves, so as to minimize the risk of residues in the soil and to avoid inadequate application levels over several years. The present paper aimed at evaluating the effect of plant growth regulators applied to the leaves, regarding their efficiency for flowering management of mango 'Tommy Atkins'. Prohexadione-Ca, trinexapac-ethyl and chlormequat chloride at the dosage of 1.0 g a.i. plant-1 acts on the regulation of vegetative growth; the period of efficiency of the products applied to the leaves lasted 20 days for prohexadione-Ca, 30 days for chlormequat cloride, and 45 days for trinexapac-ethyl.

Objetivou-se com este trabalho avaliar o efeito de doses e épocas deaplicação de três reguladores de crescimento na elongação do colmo de plantas de trigo. O experimento, conduzido em Viçosa, Estado de Minas Gerais, de maio a setembro de 2005, foi instalado com tratamentos em esquema fatorial e hierárquico com uma testemunha, no delineamento em blocos casualizados com quatro repetições. Os tratamentos foram 500; 1.000 e 1.500 g ha-1 de clormequat; 62,5; 125,0 e 187,5 g ha-1 detrinexapac-etil e 40; 80 e 120 g ha-1 de paclobutrazol, aplicados no estádio 6 ou 8 da escala Feeks e Large, e uma testemunha. O comprimento do colmo com trinexapac-etil foi menor do que com o clormequat, que, por sua vez, foi menor do que com o paclobutrazol. A aplicação de reguladores na época 1 promoveu maior redução dosentrenós basais, enquanto a aplicação na época 2 proporcionou maior influência no pedúnculo. O aumento das doses de clormequat e trinexapac-etil promoveu redução do comprimento do colmo e das partes que o formam. O aumento das doses de paclobutrazol promoveu respostas pouco expressivas no colmo e seus componentes.The objective of this work was to evaluate the effect of doses and times of application of three growth regulators on wheat stem elongation. The experiments were conducted in Viçosa, Minas Gerais State, from May to September 2005, in a factorial and hierarchicalrandomized block design with four repetitions and a control treatment. Treatments consisted of 500, 1000 and 1500 g ha-1 of chlormequat; 62.5, 125.0 and 187.5 g ha-1 of trinexapac-ethyl and 40, 80 and 120 g ha-1 of paclobutrazol, applied either at the 6 or 8stage of the Feeks and Large scale, with a control. Stem length with trinexapac-ethyl was smaller than with chlormequat, which was in its turn smaller than with paclobutrazol. Application of growth regulators at stage 1 produced shorter basal internodes, whereas the stage 2 application caused greater reduction in the peduncle. The increase in chlormequat and trinexapac-ethyl doses reduced length of stem and its parts. The increase in paclobutrazol doses had very small effects on wheat growth and its parts.

Visando avaliar os efeitos da aplicação do redutor de crescimento trinexapacethyl, em diferentes épocas e doses de nitrogênio, na cultivar de trigo Avante, realizou-se um experimento em Castro, Estado do Paraná, no delineamento em blocos ao acaso, em esquema fatorial 4 x 4, com quatro repetições. Os tratamentos constaram da aplicação de 100 g ha-1 de trinexapac-ethyl entre o primeiro e o segundo nó visível, o segundo e o terceiro nó visível, aplicação sequencial de metade da dose entre o primeiro e o segundo nó visível emetade entre o segundo e o terceiro nó visível e testemunha sem aplicação. As doses de nitrogênio em cobertura foram 90, 135, 180 e 225 kg ha-1. Foram avaliados estande, número de perfilhos, altura de plantas, diâmetro do colmo, acamamento, teor de nitrogênio nasfolhas, componentes da produção e produtividade. O trinexapac-ethyl reduziu a altura das plantas e a porcentagem de acamamento. A aplicação entre o primeiro e o segundo nó visível e entre o segundo e o terceiro nó visível promoveram aumento da produtividade de grãos. Oaumento da dose de nitrogênio aumentou o teor do nutriente na planta e causou maior acamamento, mas sem efeitos nos componentes de produção e na produtividade.An experiment was established in Castro, Paraná State, with the objective of evaluating the effect of trinexapac-ethyl applied at different times and in varied nitrogen rates, on the Avante wheat cultivar. The experimental design consisted of completely randomized blocks, in a 4x4 factorial scheme, with four repetitions. The treatments consisted of 100 g ha-1 of trinexapac-ethyl applied between the first and second visible node, second and thirdvisible node, sequential application of half the rate between first and second visible nodes and half between second and third visible nodes, and control (without application). The nitrogen rates were 90, 135, 180 and 225 kg ha-1. The study evaluated the stand; tiller number and plant height; stem diameter; lodging; nitrogen content inleaves; yield and components. Trinexapac-ethyl reduced plant height and lodging percentage. The application between the first and second visible nodes and between the second and third visible nodes promoted improved yield. The rise in the nitrogen rate increased the nutrient content in the plant and caused greater lodging, but withouteffect in the yield components and productivity.

In general, lodging has been controlled by restricting nitrogen fertilizer application and/or using short cultivars. Growth retardants can also be used to solve this problem.The objective of this study was to evaluate the effect of rates and application times of three growth retardants on Pioneiro wheat cultivar. The trial was carried out in Viçosa-MG, from May to September 2005, in a factorial and hierarchical scheme, in a randomized block design with four replications and a control treatment. The treatments consisted of 500, 1,000 and 1,500 g ha-1 of chlormequat; 62.5, 125 and 187.5 g ha-1 of trinexapac-ethyl and 40, 80 and 120 g ha-1 of paclobutrazol applied at growth stages 6 or 8, growth stage used on the scale of Feeks and Large, and a control treatment without growth retardant application. Only trinexapac-ethyl and chlormequat were efficient in reducing plant height; the effect of chlormequat and paclobutrazol on plant height was independent of the application time, but the trinexapac-ethyl at growth stage 8 produced shorter plant height than at stage 6. Increasing growth retardant rates produced shorter plant heights; chlormequat and paclobutrazol did not affect grain yield. However, the highest trinexapac-ethyl rates reduced wheat yield.De modo geral, o acamamento tem sido controlado mediante restrição da aplicação de fertilizantes nitrogenados e/ou o uso de cultivares de porte baixo. No entanto, esse problema também pode ser solucionado pela utilização de redutores de crescimento. Objetivou-se com este trabalho avaliar o efeito de doses e épocas de aplicação de três redutores de crescimento sobre plantas de trigo do cultivar Pioneiro. O experimento, conduzido em Viçosa-MG de maio a setembro de 2005, foi instalado com os tratamentos dispostos em esquema fatorial e hierárquico com uma testemunha, no delineamento de blocos casualizados com quatro repetições. Os tratamentos foram: 500, 1.000 e 1.500 g ha-1 de clormequat; 62,5, 125 e 187,5 g ha-1 de trinexapac-etil; e 40, 80 e 120 g ha-1 de paclobutrazol, aplicados no estádio 6 ou 8 da escala Feeks e Large, mais uma testemunha sem aplicação de redutor. O trinexapac-etil e o clormequat foram mais eficientes em reduzir a estatura das plantas de trigo. A ação do clormequat e do paclobutrazol sobre a altura das plantas foi independente da época de aplicação, porém o trinexapac-etil no estádio 8 promoveu menor altura do que no estádio 6. O aumento das doses dos redutores promoveu menor estatura das plantas; clormequat e paclobutrazol não afetaram a produtividade dos grãos. A maior dose de trinexapac-etil causou redução na produtividade do trigo.

Os redutores de crescimento têm sido utilizados com sucesso em trigo, evitando o acamamento, mas a recomendação de uso não diferencia cultivares quanto ao porte. Visando determinar a dose e a época de aplicação mais adequadas de trinexapac-ethyl (Moddus), em cultivares de trigo, realizaram-se experimentos na Fazenda Escola da Universidade Estadual de Ponta Grossa, no ano de 2005. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 2 x 2 x 6, com três repetições para cada cultivar de trigo. Os tratamentos constaram de duas doses de nitrogênio (50 e 240 kg ha-1), duas épocas de aplicação de trinexapac-ethyl (entre o 1º e o 2º nó e entre o 2º e o 3º nó perceptível) e de seis doses de trinexapac-ethyl (0, 31,2, 62,5, 93,7, 125,0 e 156,2 g ha-1). Foram utilizados oito cultivares de trigo com diferentes respostas ao acamamento: OR-1, CD-104 e CD-105 (resistentes), Alcover, Ônix e Vanguarda (moderadamente resistentes), Supera (moderadamente suscetível) e CEP24 (suscetível). Avaliaram-se características agronômicas, componentes da produção e produtividade. O clima ameno não foi favorável à ocorrência de acamamento, que foi observado somente para as menores doses de trinexapac-ethyl no cultivar CEP-24. A dose de nitrogênio afetou características da planta e a produtividade de alguns cultivares. O estádio de aplicação de trinexapac-ethyl não afetou de forma substancial a produtividade, e sim a altura das plantas, que foi menor quanto mais tardia a aplicação. Em geral, a equação de ajuste da produtividade em relação às doses de trinexapac-ethyl foi quadrática, ocorrendo aumento da produção com o aumento da dose do redutor, até um limite, variável de acordo com o cultivar.Growth reducers have been used successfully in wheat, preventing lodging, but use recommendation does not differentiate cultivar height. Experiments were conducted at the UEPG School Farm in 2005 to determine the rate and time of trinexapac-ethyl (Moddus) application in wheat cultivar. The experimental was arranged in complete randomized blocks, in a 2 x 2 x 6 factorial scheme, with three repetitions for each wheat cultivar. The treatments consisted of two nitrogen rates (50 and 240 kg ha-1), two trinexapac-ethyl application times (between first and second knot and between second and third perceivable knot) and six trinexapac-ethyl rates (0, 31.2, 62.5, 93.7, 125.0 and 156.2 g ha-1). Eight wheat cultivars of different lodging performances were used: OR-1, CD-104 and CD-105 (resistant), Alcover, Ônix and Vanguarda (moderately resistant), Supera (moderately susceptible), and CEP-24 (susceptible).Agronomical characteristics, yield components and yield were evaluated. Mild climate was not favorable to lodging occurrence, only observed for the lesser trinexapac-ethyl rates in CEP-24 cultivar. Nitrogen rate affected plant characteristics and the yield of some cultivars. The trinexapac-ethyl application stage did not substantially affect yield, but rather plant height, which became smaller the more delayed the application was. In general, yield adjustment equation in relation to the trinexapac-ethyl rates was quadratic, with yield increasing with increasing reducer rate, up to a limit, varying according to the cultivar.

Com o objetivo de avaliar os efeitos de um regulador de crescimento no cultivar de trigo IAPAR-53, em diferentes densidades de plantas e submetido a diferentes doses de nitrogênio, instalou-se um experimento na Fazenda-Escola da UEPG em Ponta Grossa-PR, no ano de 1999. O delineamento experimental foi o de blocos ao acaso, em esquema fatorial 2 x 3 x 4, com quatro repetições. Os tratamentos constaram da aplicação de 125 g i.a. ha-1 de trinexapac-ethyl e testemunha sem aplicação, em densidades de 44, 60 e 75 plantas m-1, no espaçamento de 0,17 m entre fileiras e nas doses de 0, 45, 90 e 135 kg ha-1 de nitrogênio em cobertura. A aplicação de trinexapac-ethyl resultou em plantas com menor massa seca, entrenós mais curtos, maior diâmetro do caule e aumento do número de espigas m-1, de grãos por espiga e produtividade. Com o aumento da dose de nitrogênio ocorreu aumento da estatura das plantas, do número de espigas m-1, do peso de mil grãos e da produtividade. Com o aumento da densidade de plantas, o diâmetro do caule, a massa seca das plantas e o número de grãos por espiga diminuíram e o número de espigas m-1 e o peso de mil grãos aumentaram, sem efeitos na produtividade. Não foi observado acamamento em nenhum dos tratamentos.An experiment was conducted at the UEPG "Capão da Onça" School Farm in 1999, Paraná-Brazil, to evaluate the effects of a growth regulator on the wheat cultivar IAPAR-53 grown at different plant populations and nitrogen rates. The experimental design was a randomized complete block in a 2 x 3 x 4 factorial scheme, with four replications. The treatments consisted of applying 125 g a.i. ha-1 of trinexapac-ethyl and control; plant densities of 44, 60 and 75 plants m-1 in a row spacing of 0.17 m and rates of 0, 45, 90, and 135 kg ha-1 of surface broadcast nitrogen. The application of trinexapac-ethyl resulted in less dry matter and short internodes, increased stem diameter, number of spikes m¹, and grain yield. As nitrogen rate increased, so did plant height, number of spikes m-1, grain weight, and grain yield. With the increase of plant density, stem diameter, plant dry weight and the number of grain/spike decreased; however, the number of spikes m-1 and grain weight increased with no detected effect on wheat productivity. No lodging was observed in any of the treatments.

Doses de nitrogênio e elevadas populações de plantas são utilizadas visando a obtenção de altas produtividades em trigo. Porém, estes fatores podem promover o acamamento das plantas, especialmente para as cultivares de porte médio ou alto. O uso de produtos que reduzem a estatura das plantas pode minimizar este problema. Visando avaliar o efeito do regulador de crescimento trinexapc-ethyl em diferentes populações de plantas e doses de nitrogênio, na cultivar de trigo OR-1, instalou-se um experimento na Fazenda Escola "Capão da Onça", da Universidade Estadual de Ponta Grossa, em Ponta Grossa, PR, no ano de 1999. O delineamento experimental foi blocos ao acaso em esquema fatorial 2 x 3 x 4, em quatro repetições. Os vinte e quatro tratamentos constaram da aplicação de 125 g i.a./ha de trinexapac-ethyl e testemunha; densidades de 55, 75 e 112 plantas/m no espaçamento de 0,17m entre fileiras e doses de 0, 45, 90 e 135kg/ha de nitrogênio em cobertura. A aplicação do trinexapac-ethyl resultou em plantas com entre-nós mais curtos; em aumento do número de espigas/m e da produtividade. Com o aumento da dose de nitrogênio, ocorreu aumento da estatura das plantas, do número de espigas/m e da produtividade. Com o aumento da densidade de plantas, o diâmetro do caule, a massa seca das plantas e o número de grãos por espiga diminuíram mas o número de espigas/m e o peso de mil grãos aumentaram, sem afetarem a produtividade. Não ocorreu acamamento em nenhum dos tratamentos.

One of the limitations to the plant regrowth rate is the application of different kinds of natural and synthetic growth regulators. These substances when used in small doses actively influence direct transformations in plants, causing considerable changes in their growth and development. The lawn experiment was conducted from 2002 to 2004. It was done on an experimental plot in the arrangement of randomized blocks in four replications. In the investigation the mixture of the grasses called Super Gazon was used. The mixture was cultivated in combination with four mineral multiple-nutrient fertilizers with a balanced dose of nitrogen. The growth regulator, Moddus 250 SC, produced on the basis of the active substance trinexapac – ethyl (TE) by the Swiss firm Syngenta Crop Protection AG, was also applied in the experiment as an investigation factor. It was used as a spray in the quantity 0.06 cm3·m-2. Some lawn plots were not sprayed. The measurement was done at three-day intervals when the grasses on the experimental plots where spraying was applied had 12 cm of height. The obtained results showed that trinexapac-ethyl effectively slowed down the regrowth of turfgrasses in the examined sward. The influence of the growth regulator depended also on the weather conditions during the vegetation period. The growth regulator, trinexapac–ethyl, effectively influenced the slow regrowth of turfgrasses in the sward of the Super Gazon mixture, regardless of the kind of fertilizer used or the weather conditions.

Visando avaliar os efeitos da aplicação do redutor de crescimento trinexapac-ethyl, em diferentes épocas e doses de nitrogênio, na cultivar de trigo Avante, realizou-se um experimento em Castro, Estado do Paraná, no delineamento em blocos ao acaso, em esquema fatorial 4 x 4, com quatro repetições. Os tratamentos constaram da aplicação de 100 g ha-1 de trinexapac-ethyl entre o primeiro e o segundo nó visível, o segundo e o terceiro nó visível, aplicação sequencial de metade da dose entre o primeiro e o segundo nó visível e metade entre o segundo e o terceiro nó visível e testemunha sem aplicação. As doses de nitrogênio em cobertura foram 90, 135, 180 e 225 kg ha-1. Foram avaliados estande, número de perfilhos, altura de plantas, diâmetro do colmo, acamamento, teor de nitrogênio nas folhas, componentes da produção e produtividade. O trinexapac-ethyl reduziu a altura das plantas e a porcentagem de acamamento. A aplicação entre o primeiro e o segundo nó visível e entre o segundo e o terceiro nó visível promoveram aumento da produtividade de grãos. O aumento da dose de nitrogênio aumentou o teor do nutriente na planta e causou maior acamamento, mas sem efeitos nos componentes de produção e na produtividade.

RESUMO A produção de biomassa de aveia voltada à elaboração de silagem de qualidade é dependente de elementos climáticos e nitrogênio sem ocorrência de acamamento. O objetivo do presente estudo é a definição da dose ideal do regulador de crescimento que possibilite, no máximo, 5% de acamamento de plantas de aveia, bem como a identificação das variáveis potenciais para composição do modelo de regressão linear múltipla com simulação da produtividade de biomassa à elaboração de silagem nas condições de uso do regulador, em reduzida, alta e muito alta fertilização com nitrogênio. O estudo foi conduzido em 2013, 2014 e 2015, em delineamento de blocos ao acaso, com quatro repetições em esquema fatorial 4x3, para doses de regulador (0, 200, 400 e 600mL ha-1) e doses de nitrogênio (30, 90 e 150kg ha-1), respectivamente. A dose de 495mL ha-1 de regulador se mostra eficiente na redução do acamamento de plantas de aveia em condição de reduzida, alta e muito alta fertilização com nitrogênio. A soma térmica, a precipitação, a radiação, a dose de regulador e o nitrogênio qualificam a composição do modelo de regressão linear múltipla, tornando eficiente a simulação da produtividade de biomassa da aveia para silagem ao longo do ciclo.