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Increases in plant density associated with the use of plant growth regulators, aside from modifying the plant architecture, can also change the maize yield performance. This study aims to investigate the yield components and grain yield of maize hybrids with contrasting leaf architecture, in response to different plant populations and trinexapac-ethyl rates (TE). Field experiments were conducted in two growing seasons, in a (5 x 5) factorial randomized block design. The treatments consisted of: five plant population (40, 60, 80, 100, and 120 thousand plants ha-1) and five TE rates (0, 100, 200, 300, and 400 g a.i. ha-1), with four replications, using the hybrids 2B710 HX and Status TL. We evaluated the number of rows per ear, ear length, number of grains per row, 1000-grain mass, and yield. An increased plant density reduces ear length, number of grains per row and 1000-grain mass, without changing the number of grain rows per ear. TE rates increases ear length and number of grains per row and reduces 1000-grain mass, mainly under favorable cultivation conditions. TE interacts with the plant density, changing the maize yield components with increases in grain yield, but these gains variy, according to the environment and genotype characteristics.

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.

Trinexapac-ethyl (TE) was more widely used in golf course worldwide. As a plant growth regulator, it inhibited grass development and delayed grass cutting date. Direct contact with TE by workers that handle and apply these agents can lead to harmful effects depending on the exposure dosage and duration. Many studies have focused on the growth regulation of TE in plants, while its health risks to human beings were rarely reported. Here, we investigated the risk assessment of workers directly dermal exposed to TE by using some absorbent paper patches. The exposure intensity (EI) and potential dermal exposure (PDE) of worker body sections were obtained, and different exposure patterns were compared. The EI of each body section among mixing/loading, hand-held power sprayer, and manual sprayer workers was ranging from 7.22 to 73.0 pg cm−2. The maximum EI of TE was found on hands of manual sprayers, while the minimum EI of TE was recorded on upper arms of mixing and loading workers. The maximum contribution sections was 29% for the chest and back from mixing/loading workers, 40% for the chest and back from hand-held power sprayers, and 32% for the thigh from manual sprayers. The unit weight potential dermal exposure (UWPDE) of hand-held power sprayers was 60% lower than that of manual sprayers, indicating that hand-held power sprayers were safer than those of manual sprayers. These findings revealed that trinexapac-ethyl posed relatively higher exposure risks to manual sprayer workers than other operator workers in golf course, mainly responsible for body sections of the chest and back and thigh.

Field pea (Pisum sativum) is an important economic and rotational crop in Alberta, Canada; however, standability problems are a major barrier to increasing seeded area in highly productive growing environments. Field experiments were conducted from 2015 to 2017 at three sites in the central and Peace regions of Alberta to determine if (i) pea standability and production can be improved using inter-row seeding into untilled standing wheat stubble; (ii) pea standability and production can be improved using chlormequat chloride (CCC), trinexapac-ethyl (TXP), or ethephon (ETH) plant growth regulators (PGRs); and (iii) PGR responses are cultivar-specific. Depending on the site–year, there were 16–17 inter-row seeding, PGR, and cultivar treatment combinations arranged in a randomized complete block design. Relative to the no-stubble control, inter-row seeding into 20- or 30-cm-tall, untilled wheat stubble significantly improved standability between 6% and 23% under conditions when lodging occurred. It also reduced days to maturity and increased 1000-seed weight, but had no effect on yield. Individual PGR treatments (CCC, TXP, and ETH) generally had small and inconsistent impacts on agronomic traits, yield, and seed quality. In dry conditions, PGRs reduced yield. CDC Meadow was slightly more responsive to PGR treatments than AAC Lacombe, indicating responses may be cultivar-specific. Because of the small and inconsistent responses, PGRs have little value as an agronomic tool in field pea. Alternatively, inter-row seeding into standing wheat stubble is a low-cost, easy to implement practice for improving field pea standability.

Forage sorghum presents tall plants, what makes mechanical seed harvesting a difficult task. Plant hormones can reduce plant height and facilitate the harvesting. Thus, the objective of this study was to evaluate the effect of the growth regulator trinexapac-ethyl on plant height and seed yield in forage sorghum. This research was carried out at Embrapa Maize and Sorghum, in two seasons (2017 and 2018), in a randomized complete block design, four replications and three varieties (BRS Ponta Negra, 1141574 and 0947216) under application of Trinexapac-ethyl in two stages of the plant growth (V8, V12, V8 + V12). The characteristics evaluated were: plant height, seed yield and mass of 1000 seeds. The effect of the hormone was significant in both stages of growth, with a significant reduction in plant height. The hormone applied twice at growth stages V8 + V12 had a greater effect in reducing plant height. However, the hormone reduced seed yield in the three varieties, what implies the need for further studies comparing the advantage of plant height reduction and the loss in seed yield. Made available in DSpace on 2021-10-27T13:00:27Z (GMT). No. of bitstreams: 1 Trinexapac-ethyl-reduces.pdf: 493049 bytes, checksum: 42bff85016ca6a8a2608bce5b50fbd45 (MD5) Previous issue date: 2021

Annual bluegrass seedhead suppression on golf greens by spring-applied plant growth regulators (PGR) has been erratic between years and locations. To effectively suppress annual bluegrass seedheads on greens, current information suggest ethephon must be applied before floral initiation. Rogue seedheads, however, can sometimes be found in late winter indicating that a variable proportion of annual bluegrass plants may induce floral initiation in winter. Studies were conducted in Blacksburg and Harrisonburg, VA at five separate sites between 2011 and 2012 to determine if winter applications of ethephon or mefluidide would improve annual bluegrass seedhead suppression when applied in advance of a spring, two-treatment program. A spring, two-treatment program of ethephon plus trinexapac-ethyl reduced annual bluegrass seedhead cover 22 to 55% depending on trial and less than similar mefluidide programs. Applying an early application of ethephon in January or February prior to the spring treatment program resulted in 5 to 7 times less seedhead cover at cover maxima than the spring treatment program alone. Ethephon did not injure creeping bentgrass and caused only slight and transient discoloration to annual bluegrass. Mefluidide injured both creeping bentgrass and annual bluegrass and reduced annual bluegrass population density in late spring. Programs that consisted of an early ethephon application, a spring treatment of triademifon, and two spring treatments of ethephon plus trinexapac ethyl improved seedhead suppression and turf quality but slightly increased annual bluegrass injury. Methiozolin suppressed annual bluegrass seedheads primarily through severe injury to annual bluegrass, which led to a decline in turfgrass quality and NDVI but a substantial increase in creeping bentgrass cover. Applying PGRs in winter is a novel concept and may substantially improve ethephon consistency and performance for annual bluegrass seedhead suppression on greens.Nomenclature: Ethephon; mefluidide; methiozolin, 5-(2, 6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1, 2-isoxazoline, code names: EK-5229, SJK-03, and MRC-01; triademifon; trinexapac-ethyl; annual bluegrass, Poa annua L. POAAN; creeping bentgrass, Agrostis stolonifera L.

Red fescue (Festuca rubra) is used in seed mixtures for lawns and pastures. It is prone to lodge at flowering, and plant growth regulators (PGRs) are used to prevent lodging, ensuring sufficient pollination. Seed yield and lodging were studied over three years in a red fescue field established with four seeding rates (2, 4, 6 and 8 kg ha&minus, 1) and sprayed each year with three doses of the PGR trinexapac-ethyl (250 g L&minus, 1) (0, 0.3, 0.6 and 1.2 L ha&minus, 1). Half of each plot was sprayed with the PGR and the other half was left unsprayed as control. The degree of lodging was assessed by analysing drone images in the second year of the experiment and using a 10-point scale for scoring lodging at the ground. Generally, application of PGR increased the seed yield but the effect varied between years. There was no interaction between the PGR dosage and seeding rate. We found a positive correlation between the blue intensity of the images and lodging. PGR dosage significantly affected lodging evaluated by visual ranking and the blue intensity of the images, while the seeding rates did not affect lodging. Lodging affected seed yield negatively.

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.

The plant growth regulator trinexapac-ethyl (TE) is widely used to increase seed yield by reducing lodging in many grass species, including perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.). However, the seed yield responses of annual ryegrass (Lolium multiflorum Lam.) to TE has not been widely investigated. In four field experiments, different rates of TE (between 0 and 800 g ha−1) were applied and the plant response measured. Seed yield was significantly (P

In Brazilian agriculture there are few reports on trinexapac-ethyl (TE) effects on maize plant lodging management. This study aimed to evaluate the effects of sequential application of TE sprayed on different plant growth stages of maize using the simple hybrid P30F53HR and the variety SCS 154 Fortuna. Experiments were carried out in a greenhouse in the 2013 and 2014 harvests. Plants were grown singly in 5L pots filled with 75% soil and 25% substrate. The experimental design was a randomized complete block with four replications. The following treatments were performed: (T1) control (no application of growth retardant); (T2) application at V2 (100 g a.i. ha-1); (T3) sequential application of 100 g a.i. ha-1 at V2 plus V3; (T4) sequential application of 100 g a.i. ha-1 at V2+V3+V4; (T5) single application of 300 g a.i. ha-1 at V4; (T6) sequential application of 100 g a.i. ha-1 at V2+V3+V4+V5; (T7) sequential application of 100 g a.i. ha-1 at V2+V3+V4+V5+V6 and (T8) sequential application of 100 g a.i. ha-1 at V2+V3+V4+V5+V6+V7. The some morphological characteristics of the two maize genotypes changed in response to TE treatment. From stage V4 onwards, maize plant height showed signs of sensitivity to the growth retardant. Plants in T8 (TE applied over V2 to V7) were more sensitive to TE with over 45% reduction in plant height compared with application T7 (applied from V2 to V6). This response was similar in both maize genotypes, thus indicating that plants are highly sensitive to TE after the V6 stage. RESUMO: Na cultura do milho há poucos relatos sobre o uso de trinexapac-ethyl (TE) visando o manejo do acamamento de plantas. Este estudo teve por objetivo avaliar diferentes doses sequenciais de TE aplicadas em diferentes estádios fenológicos da planta de milho, utilizando o híbrido simples P30F53HR e a variedade SCS 154 Fortuna. Os experimentos foram realizados em casa de vegetação em dois anos de cultivo: 2013 e 2014. Foram empregados vasos com capacidade para 5 L, preenchidos com 75% de solo e 25% de substrato comercial, com uma planta de milho por vaso. O delineamento experimental foi de blocos ao acaso com quatro repetições. Os tratamentos consistiram de: (T1) testemunha (sem aplicação de regulador); (T2) aplicação em V2 (100 g i.a. ha-1); (T3) aplicação de 100 g i.a. ha-1 em V2+V3; (T4) aplicação de 100 g i.a. ha-1 em V2+V3+V4; (T5) única aplicação de 300 g i.a. ha-1 em V4; (T6) aplicação de 100 g i.a. ha-1 em V2+V3+V4+V5; (T7) aplicação de 100 g i.a. ha-1 em V2+V3+V4+V5+V6; e (T8) aplicação de 100 g i.a. ha-1 em V2+V3+V4+V5+V6+V7. A partir do estádio V4 as plantas de milho apresentaram sinais de sensibilidade ao regulador de crescimento; a aplicação de V2 a V7 (T8), comparada à de V2 a V6 (T7), evidenciou que as plantas foram mais sensíveis ao TE, com redução superior a 45% na estatura de planta - resposta esta similar entre os dois genótipos de milho. Os resultados indicam que após o estádio V6 as plantas são altamente sensíveis ao trinexapac-ethyl.

BACKGROUND: Trinexapac-ethyl is a plant growth regulator (PGR) that inhibits the biosynthesis of plant growth hormone (gibberellin). It is used for the prevention of lodging, increasing yields of cereals, and reducing mowing of turf. The experiment was conducted to establish a determination method for trinexapac-ethyl and its metabolites trinexapac in agricultural products using LC-MS/MS.METHODS AND RESULTS: Trinexapac-ethyl and trinexapac were extracted from agricultural products with methanol/ distilled water and the extract was partitioned with dichloromethane and then detected by LC-MS/MS. Limit of detection(LOD) was 0.003 mg/kg and limit of quantification(LOQ) was 0.01 mg/kg, respectively. Matrix matched calibration curves were linear over the calibration ranges (0.01-1.0 mg/L) for all the analytes into blank extract withr2> 0.997. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, 10LOQ, 50LOQ,n

Trinexapac-ethyl and sulfometuron-methyl are the most widely used ripeners in sugarcane. The application is performed by airborne spraying. Thus, if weather conditions are unfavorable, spray drift to neighboring areas may occur. The objective of this study was to assess the selectivity of the plant growth regulators trinexapac-ethyl and sulfometuron-methyl, used as sugarcane ripeners, to eucalyptus (Eucalyptus urograndis) young plants. The experiment was installed in an eucalyptus commercial yield area, in the municipality of Tambaú, state of São Paulo, Brazil, and arranged in a 2 x 8 factorial design in randomized blocks with four replications. The treatments studied were trinexapac-ethyl and sulfometuron-methyl, sprayed in eight doses, 0; 1.0; 2.5; 5.0; 10; 25; 50 and 100% of the dose used in sugarcane as ripeners (200 g ha-1 of trinexapac-ethyl and 15 g ha-1 of sulfometuron-methyl). Chemical ripeners were applied on eucalyptus plants with 48 cm in height on average; 10.1 branches; 4.5 mm of stem diameter and 44.3 cm of crown diameter, at 46 days after seeding. Trinexapac-ethyl was selective to eucalyptus and stimulated crown diameter growth. At higher doses, sulfometuron-methyl promoted severe noticeable injuries in eucalyptus plants, such as apical bud death. However, during the assessment period the plants recovered and the visual symptoms of phytotoxicity and growth alterations were not observed at 60 days after application. The plant growth regulators trinexapac-ethyl and sulfometuron-methyl were selective to eucalyptus young plants. Entre os maturadores, o trinexapac-ethyl e o sulfometuron-methyl são os mais usados nos canaviais. A pulverização é aérea, de modo que, se as condições meteorológicas não forem favoráveis, poderá ocorrer deriva para culturas vizinhas. Assim, objetivou-se neste trabalho avaliar a seletividade dos reguladores vegetais trinexapac-ethyl e sulfometuron-methyl, utilizados como maturadores em cana-de-açúcar, para plantas jovens de eucalipto (Eucalyptus urograndis). O experimento foi instalado em área de produção comercial de eucalipto, no município de Tambaú, SP, Brasil. O delineamento experimental foi o de blocos ao acaso, em esquema fatorial 2 x 8, com quatro repetições. Os tratamentos estudados foram trinexapac-ethyl e sulfometuron-methyl, pulverizados em oito dosagens: 0; 1,0; 2,5; 5,0; 10; 25; 50; e 100% da dose utilizada em cana-de-açúcar como maturador (200 g ha-1 de trinexapac-ethyl e 15 g ha-1 de sulfometuron-methyl). Os reguladores de crescimento foram aplicados sobre as plantas de eucalipto com 48 cm de altura, 10,1 ramos, 4,5 mm de diâmetro de caule e 44,3 cm de diâmetro de copa, aos 46 dias após o plantio. O trinexapac-ethyl foi seletivo para o eucalipto e estimulou o crescimento do diâmetro de copa. Já o sulfometuron-methyl, nas maiores doses testadas, ocasionou injúrias visuais severas às plantas de eucalipto, como a morte de gemas apicais. Contudo, no decorrer das avaliações, as plantas recuperaram-se, não sendo observados sintomas visuais de fitointoxicação ou alteração do crescimento aos 60 dias após a aplicação. Os reguladores vegetais trinexapac-ethyl e sulfometuron-methyl foram seletivos para plantas jovens de eucalipto.

Bacterial etiolation, caused by Acidovorax avenae and Xanthomonas translucens , has become a widespread problem in turfgrass throughout the U.S. Various management tactics are used in managing this disease and differ among turfgrass managers. The use of biostimulants and trinexapac-ethyl (TE) has become a staple in putting green management and many products have been associated with etiolation outbreaks. Experiments performed in field and controlled environments evaluated the impact of commercial biostimulants and TE on etiolation of creeping bentgrass ( Agrostis stolonifera L. c.v. ‘Penn A-1’) caused by both A. avenae and X. translucens. In the field, a factorial study was arranged as a split-plot randomized complete block design with 4 replications. The main plot consisted of biostimulants (Knife Plus, CytoGro, Astron, Nitrozyme, PerkUp, BioMax, and none) applied at label rates while the subplot treatments consisted of TE application frequency (0.049 kg ha −1 applied at 7 d, 14 d, and none). For controlled environment experiments, biostimulant and TE treatments were arranged in a randomized complete block design with 4 replications. Bacterial etiolation was measured regularly when present using a grid count to determine the percent area exhibiting etiolation in the field while etiolated turfgrass plants were counted individually in controlled environments. Turf quality was also rated using a scale of 1–9 with 1 = completely dead, 9 = best, and 5 = minimum acceptable turf quality for all experiments. Biostimulant treatments did not have a significant effect on etiolation caused by either bacterium. Trinexapac-ethyl decreased etiolation caused by X. translucens and increased etiolation caused by A. avenae. These results support the necessity of identifying bacteria associated with etiolation as variable effects were observed with TE treatments. These factors should be considered when developing plant growth regulator programs if etiolation is problematic. Future research to evaluate phytohormone production in these bacteria may improve our understanding of etiolation development while improving methods for control.

Published in Agron. J. 107:951–956 (2015) doi:10.2134/agronj14.0399 Copyright © 2015 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. ABSTRACT Trinexapac-ethyl (TE) plant growth regulator (PGR) effects on diploid red clover (Trifolium pratense L.) seed production were investigated in two diverse environments, Canterbury (CA), New Zealand (NZ), and Willamette Valley, Oregon (OR). Five TE rate (250 and 500 g a.i. ha–1) and timing [Biologische Bundesanstalt, Bundessortenamt, and CHemische Industrie (BBCH) growth stages 32, 51, 32 + 51] treatments and an untreated control were examined at six on-farm sites in OR and one experimental site in CA in 2011 and 2012. Seed yield was increased across CA and OR production environments with 500 g ha–1 TE applied at BBCH 32 (15%, CA-2011; 9%, OR-2011; 13%, OR-2012). Split applications of 500 g ha–1 TE (BBCH 32 + 51) improved seed yield by up to 13% in OR but had no effect in CA. Seed weight was generally inversely related to yield; TE treatments that produced the highest yield also had the lowest seed weight and thus did not contribute to TE-induced yield improvement. Increases in inflorescences m–2 with TE ranged from 26 to 62% in all environments. Coupled with other measured effects of TE on flowering and stem production, these may have been contributing factors to seed yield enhancement by TE. Crop height was consistently reduced by TE across CA and OR environments but aboveground crop biomass was not affected by TE. The timely use of TE PGR is a practice that has broad applicability in red clover seed production across CA and OR environments.

Trinexapac-ethyl (TE) has been used for lodging control and seed yield enhancement in several grass seed crop species but little is known about how this plant growth regulator (PGR) performs in tall fescue [ Schedonorus arundinaceus (Shreb.) Dumort.]. The objective of this study was to determine how TE application rate and timing influences seed productivity over six diverse lodging environments in Oregon's Willamette Valley. Three field trials were conducted to examine TE effects on seed yield and yield components. Stem length, a key factor in lodging control, was reduced incrementally with increasing TE rate from 17% reduction at 200 g TE ha −1 to a maximum of 39% reduction at 600 g TE ha −1 . Lodging was consistently reduced by TE but had no effect on above-ground biomass and panicles m −2 . Over environments, TE increased seed yield by an average 40% over the untreated control. However, TE rate or application timing did not differentially affect seed yield across environments. Increases in tall fescue seed yield attributable to TE were the result of increased seed number m −2 and improved harvest index (HI), but not seed weight. A better understanding of TE-induced seed yield increases will aid in improving use efficiency and economy of this important PGR.

Made available in DSpace on 2015-10-21T20:28:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-01. Added 1 bitstream(s) on 2015-10-22T09:48:08Z : No. of bitstreams: 1 WOS000356611400015.pdf: 110957 bytes, checksum: a1c3d97096b21f95ca8b3c08ba3fdd4b (MD5) Este trabalho teve o propósito de avaliar o efeito da aplicação de três inibidores de desenvolvimento vegetal sobre o crescimento e a emissão de hastes florais da grama-santo-agostinho [Stenotaphrum secundatum (Walt.) Kuntze]. O estudo foi instalado em um gramado com 15 meses de idade, no delineamento de blocos casualizados, com quatro repetições e os tratamentos compostos por aplicação única de trinexapac-ethyl (113, 226, 452, 678 e 904 g ia ha-1), prohexadione-calcium (100 e 200 g ia ha-1) e bispyribac-sodium (40 e 60 g ia ha-1), além de uma testemunha sem aplicação de inibidor de crescimento. O efeito dos tratamentos foi avaliado quanto à fitointoxicação, por meio de avaliação visual, altura de plantas, altura e emissão de hastes florais e produção total de massa seca de aparas. Todos os inibidores de desenvolvimento vegetal proporcionaram injúrias visíveis sobre a grama-santo-agostinho, mas todos os sintomas de intoxicação praticamente regrediram aos 28 dias após a aplicação. O trinexapac-ethyl aplicado na dose de 904 g ia ha-1 proporcionou redução de 59,7% na altura da grama, de 96,4% e 87,7% na emissão de hastes florais e na quantidade total de massa seca de aparas produzidas pela grama, respectivamente. Gramados formados com grama-santo-agostinho podem ser manejados com a aplicação de inibidor vegetal, com a redução da necessidade de cortes por um período de até 119 dias após a aplicação, sem efeitos severos sobre o aspecto visual sobre o gramado. The objective of this work was to evaluate the effects of three plant growth inhibitors on the development and emission of floral rachis of Saint Augustine grass [Stenotaphrum secundatum (Walt.) Kuntzel] plants. The study was carried out in a 15 month old lawn with the experimental plots being distributed in accordance with a complete randomized block design with four replications. The treatments consisted of sole application of trinexapac-ethyl (113, 226, 452, 678, and 904 g ai ha(-1)), prohexadione-calcium (100 and 200 g ai ha(-1)), and bispyribac-sodium (40 and 60 g ai ha(-1)) plus a check treatment in which the plants were not submitted to any of the plant growth inhibitors. The effects of those products were evaluated in terms of visual signs of plant intoxication, plant height, emission and height of floral rachises, and chip total dry matter production. All the plant growth inhibitors resulted in visible injury to the plants but these intoxication signs practically disappeared 28 days after the application. Trinexapac-ethyl at the dose of 904 g ai ha(-1) reduced plant height by 59.7%, the emission of floral rachis by 96.4%, and the amount of chip dry matter production by 87.7%. Plant growth inhibitors may reduce the number of times of lawn plants cutting up to 119 days after their application with no harmful effects on the plants visual aspect. Universidade Estadual do Oeste do Paraná, Centro de Ciências Agrárias Universidade Estadual Paulista, Departamento de Produção Vegetal, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal

The seed yield response of cocksfoot (Dactylis glomerata L.) to stem-shortening plant growth regulators (PGRs) chlormequat chloride (CCC) and trinexapac-ethyl (TE) applied during stem elongation were evaluated in eight field trials in Canterbury; five irrigated and three non-irrigated. Across all trials and treatments the average seed yield increase was 53% resulting in an extra 290 kg/ha. In irrigated trials, the average response to PGRs was 68%, resulting in an extra 380 kg/ha of seed, compared with an average 27% response in non-irrigated trials. A mixture of CCC + TE (either 750 + 100 or 1500 + 200 g active ingredient [ai]/ha), applied at Zadoks growth stage (GS) 32 or split between GS 32 and GS 37–39, provided the largest and most consistent seed yield response of 86%, an extra 450 kg/ha. Reduced lodging was a factor in one trial only. In all trials, reduced stem length was associated with increased seed yield even in the absence of lodging. Seed yields increased at 12.5 kg/ha for every cm reduction ...

Application of trinexapac-ethyl (TE) plant growth regulator (PGR) for lodging control in perennial ryegrass ( Lolium perenne L.) is a widespread practice, but information on how this PGR increases yield is limited. The objective of this study was to determine how TE application rate and timing influences seed productivity over nine diverse lodging environments in Oregon's Willamette Valley. Four field trials were conducted to examine TE effects on seed yield and yield components. Stem length, a key factor in lodging control, was reduced incrementally with increasing rate of TE to a maximum of 28%. TE consistently reduced lodging but had no effect on the seed yield components spikes m −2 , spikelets spike −1 , and florets spikelet −1 . Over environments, TE increased seed yield by an average 43% over the untreated control at 400 g ai ha −1 TE. Best seed yield results across environments were attained with TE applied between BBCH 32 and 51. The number of seeds spikelet −1 , seed mass spikelet −1 , and seed set were increased by TE. TE-induced seed yield increases were attributable to increased seed number m −2 and improved seed set, but not seed weight. A better understanding of TE-induced seed yield increases will aid in improving use efficiency and economy of this important PGR.

Annual bluegrass (Poa annua L.) is a problematic weed on creeping bentgrass (Agrostis stolonifera L.) putting greens. Annual bluegrass produces extensive seedheads in spring, and plant growth regulators (PGRs) are frequently used to suppress seedhead formation. This study investigated the effects of single and sequential applications of mefluidide, maleic hydrazide, and ethephon alone or in combination with trinexapac-ethyl (TE), on annual bluegrass seedhead formation. A secondary objective evaluated whether addition of TE enhanced the efficacy of ethephon while improving the safety on creeping bentgrass. Three independent studies were established on golf course greens during a 2-yr period, with initial PGRs application before annual bluegrass seedhead formation. Regardless of PGR treatment, single or sequential applications in all studies showed no differences in annual bluegrass seedhead suppression. Ethephon-containing treatments provided the best seedhead suppression with up to 95% reduction. No PGR treatments caused visible phytotoxicity to creeping bentgrass following single applications. Sequential applications of both mefluidide and maleic hydrazide caused significant phytotoxicity to creeping bentgrass for up to 3 wk after initial treatment (WAIT). With the exception of one evaluation date in the third study, tank mixture of TE with ethephon had little effect on annual bluegrass seedhead suppression. Tank-mixing TE with ethephon marginally enhanced turf quality of creeping bentgrass up to 6% compared to ethephon alone.

Made available in DSpace on 2018-11-12T17:27:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01. Added 1 bitstream(s) on 2018-11-12T17:35:51Z : No. of bitstreams: 1 S1983-21252016000200320.pdf: 465005 bytes, checksum: 8f835967570de5ab59fd618761c5e6fc (MD5) RESUMO: Um dos grandes problemas de alguns cultivares de arroz de terras altas é o aumento do porte da planta quando submetido a altas doses de fertilizante nitrogenado, atingindo altos índices de acamamento. Uma opção para diminuir a altura das plantas de arroz, e com isso também o acamamento, seria a utilização de reguladores vegetais, entretanto, existem poucas informações sobre o efeito desses reguladores nos processos fisiológicos da planta. Assim, objetivou-se, por meio da análise de crescimento e de trocas gasosas, avaliar a influência da aplicação de etil-trinexapac na cultura do arroz de terras altas. O experimento foi conduzido em casa-de-vegetação usando-se a cultivar BRS Primavera. Foi utilizado o delineamento experimental inteiramente casualizado, com oito repetições. Os tratamentos foram constituídos sem e com aplicação de regulador de crescimento vegetal e dois estádios de desenvolvimento avaliados. Foram estimados os índices fisiológicos e trocas gasosas. O uso de regulador de crescimento etil-trinexapac proporcionou melhor desenvolvimento das plantas de arroz do estádio de florescimento a maturação fisiológica, resultando em valores de RAF, AFE e PMF mais elevados nas plantas tratadas. Paralelamente, proporcionou menor redução na assimilação líquida de CO2 na fase de maturação fisiológica. Assim, a TAL não sofreu alteração em função do regulador de crescimento e a TCR apresentou redução nas plantas tratadas. Estes resultados indicam a ocorrência de autosombreamento na cultura induzida pela concentração do etil-trinexapac, que pode ter sido supra ótima. ABSTRACT: A major problem affecting some upland rice cultivars is the increase in plant size when subjected to high doses of nitrogen fertilizer, leading to high levels of lodging. A method to reduce the height of upland rice, and therefore lodging, would be to use plant growth regulators. However, little information exists on the effect of these regulators on plant physiological processes. Therefore, the objective of this study was to evaluate the influence of trinexapac-ethyl application in upland rice via analysis of growth and gas exchange. The experiment was carried out under greenhouse conditions using the BRS Primavera cultivar. A completely randomized design with eight replications was used. Treatments were carried out with and without the application of the plant growth regulator, and plants were subject to two-stage assessments in which physiological and gas-exchange indices were measured. The use of trinexapac-ethyl improved the growth of rice plants from the flowering to the physiological maturity stage, resulting in higher values of leaf area ratio, specific leaf area, and leaf matter ratio in treated plants. At the same time, it provided smaller reduction in net CO2 assimilation at the physiological maturity stage. Thus, net/apparent assimilation rate did not change after the application of growth regulator, but relative growth rate decreased in these treated plants. These results indicate the occurrence of self-shading in rice plants induced by what might be a supra-optimum trinexapac-ethyl concentration. Universidade Federal de Mato Grosso do Sul Departament of Agronomy Universidade Estadual Paulista School of Agronomic Sciences Department of Production and Plant Breeding Embrapa Arroz e Feijão Universidade Estadual Paulista Institute of Biosciences Department of Botany Universidade Estadual Paulista School of Agronomic Sciences Department of Production and Plant Breeding Universidade Estadual Paulista Institute of Biosciences Department of Botany

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:18Z No. of bitstreams: 1 S0103-90162012000300004.pdf: 273621 bytes, checksum: e4280d510a293074a87baa8144ed359e (MD5) Made available in DSpace on 2013-08-22T19:01:18Z (GMT). No. of bitstreams: 1 S0103-90162012000300004.pdf: 273621 bytes, checksum: e4280d510a293074a87baa8144ed359e (MD5) Previous issue date: 2012-06-01 Made available in DSpace on 2013-09-30T20:01:10Z (GMT). No. of bitstreams: 2 S0103-90162012000300004.pdf: 273621 bytes, checksum: e4280d510a293074a87baa8144ed359e (MD5) S0103-90162012000300004.pdf.txt: 34909 bytes, checksum: a97c53cce9d7a995580ebe098d1a5fcb (MD5) Previous issue date: 2012-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:14:40Z No. of bitstreams: 2 S0103-90162012000300004.pdf: 273621 bytes, checksum: e4280d510a293074a87baa8144ed359e (MD5) S0103-90162012000300004.pdf.txt: 34909 bytes, checksum: a97c53cce9d7a995580ebe098d1a5fcb (MD5) Made available in DSpace on 2014-05-20T13:14:40Z (GMT). No. of bitstreams: 2 S0103-90162012000300004.pdf: 273621 bytes, checksum: e4280d510a293074a87baa8144ed359e (MD5) S0103-90162012000300004.pdf.txt: 34909 bytes, checksum: a97c53cce9d7a995580ebe098d1a5fcb (MD5) Previous issue date: 2012-06-01 The aerial spraying of plant ripeners on sugar cane (Saccharum officinarum L.) crops causes often the contamination of neighboring areas, which subsidizes formal complaints from the neighbors. These contaminations are due to spraying taking place during inadequate environmental conditions or from technical mistakes during the application. One of the most important causes of this contamination is the susceptibility of the species being cultivated surrounding sugar cane. In order to evaluate the effects of sugar cane plant ripeners trinexapac-ethyl and sulfometuron-methyl on peanuts, cotton, potato, coffee, citrus, beans, sunflower, cassava, rubber, soybean, and grapes, eleven experiments - one for each species - were carried out from May 2009 to Jan. 2010. The field experiment was set according to a completely random design with five treatments and four replications. Just before or during flowering, a single treatment of trinexapac-ethyl at 100 or 200 g ha-1 and sulfometuron-methyl at 7.5 or 15 g ha-1 was applied to plants. A control treatment (plants not treated) for each species was part of each experiment. Trinexapac, at the doses of 100 and 200 g ha-1, showed selectivity to peanuts, cotton, potato, coffee, citrus, sunflower, cassava, rubber, soybean, and grape. At the lowest dose (100 g ha-1), it was selective for bean. Sulfometuron, at the dose of 7.5 g ha-1, was selective for peanuts and, at the two studied doses (7.5 and 15 g ha-1), it was selective for coffee, citrus, cassava, and rubber. UNESP FCAV, Depto Fitossanidade, BR-14884900 Jaboticabal, SP, Brazil UNESP FCAV, Depto Fitossanidade, BR-14884900 Jaboticabal, SP, Brazil

The plant growth regulator trinexapac-ethyl (TE) [4-(cyclopropyl-a-hydroxymethylene)-3,5dioxo-cyclohexanecarboxylic acid ethylester] reduces turfgrass clipping yield and enhances turfgrass color and density. Typically, such responses are achieved through alteration of N application rate, yet few have comprehensively investigated the effect of TE on turfgrass N requirements. We hypothesized that TE reduces putting green N requirements without sacrifi cing turfgrass quality. A three year study was conducted on a creeping bentgrass (Agrostis stolonifera L.) putting green with treatments consisting of three N application rates (5, 10, and 20 kg N ha–1 14 d–1) with or without TE application. To sustain season-long growth suppression, TE was applied at 0.10 kg a.i. ha–1 every 200 growing degree days (GDD; base 0°C). Turfgrass yield and color were quantifi ed every other week, and clipping tissue N content was analyzed monthly. Clipping yield, tissue N content, N removal, and color index increased with N rate. All attributes responded linearly to N application rate. Trinexapac-ethyl enhanced color while suppressing clipping yield and nutrient removal from mowing. As a result, TE reduced creeping bentgrass putting green N requirements by 25% conservatively and on several occasions by greater than 50%. W.C. Kreuser, Department of Horticulture, Cornell University, Ithaca, NY 14853; D.J. Soldat, Department of Soil Science, University of Wisconsin-Madison, Madison, WI 53706. Received 18 July 2011. *Corresponding author (wck38@cornell.edu). Abbreviations: GDD, growing degree days; TE, trinexapac-ethyl. Published in Crop Sci. 52:1348–1357 (2012). doi: 10.2135/cropsci2011.07.0364 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.

The plant growth regulator trinexapac-ethyl (TE) is widely used to enhance ryegrass seed yields by reducing lodging (i.e. delaying collapse of the crop). However, lodging data are usually a single evaluation related to TE rate for a particular date of measurement. In eight field trials with varying rates of TE, weekly lodging assessments were made from full head emergence and days to 50% lodging were determined. In all trials, dynamic assessment of TE treatment showed there was a strong positive correlation (R 2 = 0.82) between the number of days to 50% lodging and seed yield. Nil TE reached 50% lodging in 7 days compared with 33 days for TE treatments of 400 g ha−1. On average, one days’ delay in reaching 50% lodging increased seed yield by 24 kg ha−1 (response range 16–33 kg ha−1). The data indicate that TE rate per se is less important than the rate required to delay the date that 50% lodging is reached. The seed yield response was linear for delayed lodging from full head emergence to harvest...

Use of seeded-bermudagrasses (Cynondon dactylon) is expanding rapidly, especially on high-use athletic fields. Previous work has defined significant differences in several parameters among cultivars. Experiments were conducted in Lexington, KY, in 2004 and 2005 to test the tolerance of the cultivars Riviera, Princess, Transcontinental, Savannah, Yukon, and the experimental line SWI 1012, with and without applications of trinexapac-ethyl to simulated athletic traffic. Plots were established in June of each year and managed as athletic field turf. Simulated traffic was applied using a Brinkman traffic simulator during high school football seasons in Kentucky at a level roughly equivalent to three games per week. Percentage of bermudagrass cover was visually rated weekly during the trafficking periods each year. Turfgrass quality was rated once before beginning traffic treatments each year. There were no consistent significant interactions (P > 0.05) among trinexapac-ethyl treatments and cultivars in either year of the study for either response variable. The main effect of cultivars was highly significant (P < 0.0001) for percentage of bermudagrass cover in both years of the study. Among cultivars, the ranges of percentage of bermudagrass cover at the end of the trafficking periods were 10.2% to 39.2% and 43.3% to 76.7% in 2004 and 2005, respectively. The main effects of trinexapac-ethyl on percentage of bermudagrass cover were significant (P < 0.0052) and more pronounced in 2004. Significant differences (P < 0.0200) were also recorded in 2005. Applications of trinexapac-ethyl resulted in increased tolerance to simulated traffic and improved turfgrass quality. Under the conditions of this study, data indicate that both cultivars and regular applications of trinexapac-ethyl have significant effects on overall turfgrass quality and the tolerance of these seeded bermudagrasses to simulated traffic.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:00:10Z No. of bitstreams: 1 S0103-84782010000200004.pdf: 158518 bytes, checksum: fcf2fb7cd77e5f11e98527be0304be47 (MD5) Made available in DSpace on 2013-08-22T19:00:10Z (GMT). No. of bitstreams: 1 S0103-84782010000200004.pdf: 158518 bytes, checksum: fcf2fb7cd77e5f11e98527be0304be47 (MD5) Previous issue date: 2010-02-01 Made available in DSpace on 2013-09-30T19:58:11Z (GMT). No. of bitstreams: 2 S0103-84782010000200004.pdf: 158518 bytes, checksum: fcf2fb7cd77e5f11e98527be0304be47 (MD5) S0103-84782010000200004.pdf.txt: 25251 bytes, checksum: 092f08c20a3e45fb4cd0c99ae6bbaef7 (MD5) Previous issue date: 2010-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:02Z No. of bitstreams: 2 S0103-84782010000200004.pdf: 158518 bytes, checksum: fcf2fb7cd77e5f11e98527be0304be47 (MD5) S0103-84782010000200004.pdf.txt: 25251 bytes, checksum: 092f08c20a3e45fb4cd0c99ae6bbaef7 (MD5) Made available in DSpace on 2014-05-20T15:15:02Z (GMT). No. of bitstreams: 2 S0103-84782010000200004.pdf: 158518 bytes, checksum: fcf2fb7cd77e5f11e98527be0304be47 (MD5) S0103-84782010000200004.pdf.txt: 25251 bytes, checksum: 092f08c20a3e45fb4cd0c99ae6bbaef7 (MD5) Previous issue date: 2010-02-01 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. Empresa Brasileira de Pesquisa Agropecuária Semiárido Universidade Estadual Paulista Instituto de Biociências Departamento de Botânica Universidade Estadual Paulista Instituto de Biociências Departamento de Botânica

The introduction of the plant growth regulator trinexapac-ethyl (Moddus) has increased seed yields in perennial ryegrass (Lolium perenne) by up to 50% in New Zealand. Application rates from ten trials have confirmed that approximately 1.6 l/ha are optimum. Yield increases are a result of increased harvest index and better dry matter partitioning to the harvested parts. The resulting changes in harvest components include increasing seed head density and seeds per spikelet (better seed retention) associated with delayed lodging. Keywords: Lolium perenne, lodging, Moddus, seeds/spikelet, trinexapac-ethyl

Dwarf bermudagrass (Cynodon dactylon x C. transvaalensis Burtt-Davy) and creeping bentgrass (Agrostis stolonifera L.) are planted for golf greens in the U.S. transition zone, but management regimes, such as the use of a plant growth regulator (PGR), often vary for long-term culture of the two species. The objective of this experiment was to investigate application regimens of the PGR trinexapac-ethyl (TE), on growth, quality, and performance of creeping bentgrass and bermudagrass putting greens in Clemson, SC. 'L-93' creeping bentgrass and 'TifEagle' bermudagrass putting greens, established in summer 2002 and mowed at 3.2 mm, received TE over 12 wk in three regimens: 0.017 kg ha 1 wk -1 , 0.033 kg ha) -1 2 wk -1 (biweekly), or 0.05 kg ha -1 3 wk -1 (triweekly) from May to August 2003 and 2004. Creeping bentgrass was not discolored from TE, but unacceptable bermudagrass discoloration (>20%) occurred on one, two, and six dates for weekly, biweekly, and triweekly regimens, respectively. All TE regimens reduced bermudagrass clippings approximately 50% from nontreated bermudagrass across all dates, while creeping bentgrass clipping reductions, approximately 20 to 35% from nontreated grass, were inconsistent. The root masses of both species treated with TE regimens were similar to nontreated turf. Bermudagrass aerification recovery was reduced on two, two, and four dates after weekly, biweekly, and triweekly TE regimens, respectively. All TE regimens increased morning and evening bermudagrass golf ball roll distance approximately 25 cm from morning distances of nontreated turf.

Trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] and paclobutrazol (PAC) [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-tri-azol-1-yl)pentan-3-ol] are routinely used to suppress clipping production. Single-leaf turfgrass C exchange rates (CERs) in response to plant growth regulator (PGR) treatment have not been characterized. Individual Kentucky bluegrass (KBG, Poa pratensis L.) plants received label rates of TE or PAC and were placed in growth chambers at 23/18 or 30/25°C. Photosynthetic efficiency and CER measurements were recorded every 4 d for 44 d. Total root length (TRL), root surface area (SA), and average root diameter were measured at the end of the study. Reductions in CERs of TE- or PAC-treated plants were short lived with CERs suppressed 17 to 29% of control (POC) at 4 and 12 days after treatment (DAT), respectively. Plants treated at 23/18°C with PGRs typically had short-lived increases in CERs following CER suppression. A similar pattern of CER response to PGR treatment was observed at the 30/25°C temperature regime. Quantum efficiency was unaffected, but plants treated with PGRs had reduced root growth. PAC caused the greatest reduction in TRL and SA while increasing root diameter. A decline in TRL and SA in conjunction with increased tillering indicates that PGR reduced TRL and SA on a tiller basis. Changes in single-leaf CERs do not fully explain PGR-induced changes in plant growth.

Growth regulators can be used to further retard or inhibit vegetative growth. In this sense, the objective of this study was to determine the effects of age and number of trinexapac-ethyl applications on the growth and yield of sugarcane. The experiment was in a randomized complete block design with four replications. The treatments were in a 3 x 2 + 2 factorial arrangement, where factor A corresponded to the application times of the plant growth regulator (120, 200 and 240 days after bud burst (DAB) of sugarcane) and factor B to the number of applications (one or two applications). In addition, two controls (one with three applications and another application without the regulator) were added. The application of trinexapac-ethyl decreased the number and the distance between buds, height, root volume and sugarcane yield. The sequential application (2 or 3 times) induced an increase in stem diameter and three applications of the product increased the number of plant tillers. The use of growth regulators applied at 240 DAB has reduced plant height, however without changing the number of buds. It can be concluded that trinexapac-ethyl changes sugarcane growth and yield, regardless of season and number of applications. RESUMO - Os reguladores vegetais podem ser utilizados para promover, retardar ou inibir o crescimento vegetativo. Neste sentido, o objetivo deste trabalho foi determinar os efeitos de épocas e número de aplicações do trinexapac-ethyl sobre o crescimento e a produtividade da cana-de-açúcar. O experimento foi delineado em blocos casualizados com quatro repetições. Os tratamentos foram arranjados em esquema fatorial (3 x 2 + 2); o fator A correspondeu às épocas de aplicação do regulador vegetal (120, 200 e 240 dias após a brotação das gemas (DAB) da cana-de-açúcar), e o fator B, ao número de aplicações (uma ou duas). Além disso, foram adicionadas duas testemunhas (uma com três aplicações e outra sem aplicação do regulador). A aplicação do trinexapac-ethyl reduziu o número e a distância entre gemas, a altura, o volume radicular e a produtividade da cana-de-açúcar. A aplicação sequencial (duas ou três vezes) promoveu incremento no diâmetro do caule, e três aplicações do produto aumentaram o número de perfilhos das plantas. O uso do regulador vegetal aplicado aos 240 DAB reduziu a altura das plantas, porém sem alterar o número de gemas. Conclui-se que o trinexapac-ethyl altera o crescimento e a produção da cana-de-açúcar, independentemente da época e do número de aplicações.

O objetivo deste trabalho foi avaliar os efeitos da aplicação de concentrações do regulador de crescimento etil-trinexapac na altura de planta, no acamamento e na produtividade de grãos da cultivar de aveia-branca Barbarasul, em diferentes ambientes de cultivo e doses de nitrogênio. Os experimentos foram conduzidos nas safras 2010 e 2011 nos municípios de Capão do Leão e Augusto Pestana, no Estado do Rio Grande do Sul, e nas safras 2010 e 2012 no Município de Lages, no Estado de Santa Catarina. Utilizou-se o delineamento de blocos ao acaso, em arranjo fatorial 4x2x6 (dose de etil-trinexapac, estádio de desenvolvimento da planta e ambiente), com quatro repetições constituídas por parcelas úteis de 3,0 m2. Em cada ambiente, realizou-se adubação nitrogenada com 30 e 90 kg ha-1 de N. Foram avaliados os caracteres altura de planta, percentagem de acamamento e produtividade de grãos. A aplicação do regulador de crescimento etil-trinexapac nas doses de 100 a 150 g i.a. ha-1 em plantas de aveia-branca 'Barbarasul', nos estádios E31 e E32, reduz a altura das plantas e a percentagem de acamamento, sem prejuízos à produtividade de grãos. A intensidade da redução do acamamento depende das características do ambiente de cultivo. The objective of this work was to evaluate the effects of the application of doses of the plant growth regulator trinexapac-ethyl on plant height, lodging index, and grain yield of the white oat cultivar Barbarasul at different cultivation environments and nitrogen doses. The experiments were conducted in the 2010 and 2011 crop seasons in the municipalities of Capão do Leão and Augusto Pestana, in the state of Rio Grande do Sul, and in the 2010 and 2012 crop seasons in the municipality of Lages, in the state of Santa Catarina, Brazil. A randomized complete block design was used, in a 4x2x6 factorial arrangement (dose of trinexapac-ethyl, development stage, and environment), with four replicates consisting of 3.0 m2 plots. In each environment, nitrogen fertilization was done with 30 and 90 kg ha-1 N. The evaluated traits were plant height, lodging index percentage, and grain yield. The application of the growth regulator trinexapac-ethyl, at the doses of 100 to 150 g a.i. ha-1 in 'Barbarasul' white oat plants, in the E31 and E32 development stages, reduces plant height and the percentage of lodging, without harming grain yield. The intensity of the reduction in lodging depends on the conditions of the cultivation environment.