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The objective of this work was to evaluate the effect of application of the growth regulator Trinexapac-ethyl on maize response to the increase in plant density at two sowing dates. A field experiment was carried out in the municipality of Lages, state of Santa Catarina, Brazil, during the 2014/2015 and 2015/2016 growing seasons. Two sowing dates (10/15 - preferential, and 12/5 - late), four plant densities (5, 7, 9, and 11 plants m-2), with and without Trinexapac-ethyl application, were tested. The growth regulator was sprayed at a rate of 150 g a.i. ha-1, when hybrid P30F53YH was at the V5 and V10 growth stages. The spraying of Trinexapac-ethyl decreased the stem length above the ear insertion node at both growing seasons. Grain yield ranged from 11,422 to 14,805 kg ha-1, and increased in a quadratic way with the increment in plant density. The highest yields were reached when maize was sown in October. The spraying of Trinexapac-ethyl did not affect grain yield, but decreased the 1,000 kernels mass at both sowing dates. The use of Trinexapac-ethyl does not enhance grain yield of maize hybrid P30F53YH at crowded stands in response to the densification, regardless of sowing time.

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.

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.

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

Summary: The use of growth regulators in wheat aims to reduce problems caused by the lodging of plants. The aim of this study was to evaluate the growth and vigor expression of wheat seeds treated with a growth regulator and the fertilization of plants to achieve high yields. The cultivar used was OR Topázio, the treatments consisted of the combination of five rates of the trinexapac-ethyl [0 - no application; 200; 400; 600 e 800 mL of the commercial product ha-1] and eight harvesting dates [14, 28, 42, 56, 70, 84, 98 e 112 days after emergence ]. The experimental design was completely randomized, in a factorial scheme 5 x 8 (five rates and eight harvest dates) with four repetitions. The total dry matter, dry matter production rate, relative growth rate, net assimilation rate, conversion efficiency of solar energy, photoassimilate partition, harvest index, and seedling emergence index were evaluated. Allocation of total dry matter, relative growth rate, plant height and harvest index were reduced by the growth regulator, with varied intensity according to the rate applied. The net assimilation rate was reduced in plants subjected to 400, 600 and 800 mL ha-1. The seedling emergence and the speed of emergence index were not affected by the action of the growth regulator. Resumen: El uso de reguladores de crecimiento en trigo tiene el objetivo de reducir los problemas causados por el acamado de plantas. El objetivo de este estudio fue evaluar la expresión del crecimiento y el vigor de las semillas de trigo, tratadas con un regulador de crecimiento, y el uso de fertilización para obtener altos rendimientos. El cultivar utilizado fue OR Topázio, y los tratamientos consistieron en la combinación de cinco concentraciones del trinexapac-etilo [0-sin aplicación; 200; 400; 600 y 800 ml de producto comercial ha-1] con ocho períodos de colecta [14, 28, 42, 56, 70, 84, 98 y 112 días después de la emergencia]. Se utilizó un diseño experimental enteramente aleatorizado, en un esquema factorial 5 x 8 (cinco concentraciones y ocho períodos de colecta), con cuatro repeticiones. Se evaluó materia seca total, tasa de producción de materia seca, tasa relativa de crecimiento, tasa de asimilación neta, eficiencia de conversión de energía solar, partición de fotoasimilados, índice de cosecha e índice de velocidad de emergencia. La acumulación de materia seca total, tasa de crecimiento relativo, altura de la planta y el índice de cosecha se redujeron con el regulador de crecimiento, con intensidad variada de acuerdo con la concentración aplicada. La tasa de asimilación neta se redujo cuando las plantas fueron sometidas a las concentraciones de 400, 600 y 800 ml ha-1. La emergencia de las plántulas y el índice de velocidad de emergencia no se vieron afectados por la acción del regulador de crecimiento.

The growth regulator modifies the expression of lodging and panicle components in oat plants, with reflexes in yield. The objective of this study was to define the optimal dose of growth regulator in oat for a maximum lodging of 5%. In addition, this study aimed to identify potential variables of the panicle to compose the multiple linear regression model and the simulation of grain yield in conditions of use of the regulator under low, high and very high fertilization with nitrogen. The study was conducted in 2011, 2012 and 2013 in a randomized block design with four replicates in a 4 x 3 factorial scheme, for growth regulator doses (0, 200, 400 and 600 mL ha-1) and N-fertilizer doses (30, 90 and 150 kg ha-1), respectively. The growth regulator doses of 395, 450 and 560 mL ha-1 are efficient, with maximum oat lodging of 5%, under low, high and very high nitrogen fertilization, respectively. The grain weight per panicle and panicle harvest index are potential variables to compose the multiple linear regression model. Multiple linear regression equations are efficient in the simulation of oat grain yield under the conditions of use of growth regulator, regardless of the N-fertilizer dose.

Studies on efficient use of the plant growth regulator can make this technology possible for leveraging oat yield in Brazil. This study aims to define the optimal dose growth regulator in oat, which allows plant lodging at most 5%. Establishing equations describe the yield indicators behavior and by using the optimal growth regulator dose for lodging, simulate the expression of these indicators regardless of reduced, high and very high conditions of nitrogen fertilization and favorable and unfavorable cultivation year. The study was conducted in 2013, 2014 and 2015, in carrying out two experiments, one to quantify the biomass yield and another aiming at estimating grain yield and lodging. The experimental design was a randomized block with four replications, following factorial scheme 4 x 3 to growth regulator doses (0, 200, 400 and 600 mL ha-1) and N-fertilizer rates (30, 90 and 150 kg ha-1), respectively. The use of 495 mL ha-1 growth regulator trinexapac-ethyl active principle is shown efficient at the reduction of oat plant lodging, regardless of the agricultural year condition and N-fertilizer rate. In the expression of grain yield and harvest index, quadratic behavior is obtained, however with decreasing linearity on the biomass yield and straw by increasing the growth regulator dose. The optimal dose of growth regulator in reducing oat lodging does not affect grain yield, but it reduces biological yield via biomass straw with elevation on the harvest index. Key words: Avena sativa, biomass, straw, harvest index, multiple linear regression

O uso do regulador de crescimento em aveia pode reduzir o acamamento de plantas com reflexos na produtividade de biomassa e graos. Objetivou-se, no estudo, determinar a viabilidade e a eficiencia do uso do regulador de crescimento Trinexapac-Ethyl em aveia branca em diferentes condicoes de uso de N-fertilizante e de ano favoravel e desfavoravel ao cultivo. Neste estudo, dois experimentos foram conduzidos nos anos de 2011, 2012 e 2013, um para quantificar a taxa de producao de biomassa e outro para determinacao da produtividade de graos e o acamamento. O delineamento experimental foi de blocos ao acaso com quatro repeticoes em esquema fatorial 4 x 3 para doses de regulador de crescimento (0, 200, 400 e 600 mL ha-1) e doses de nitrogenio (30, 90 e 150 kg ha-1) respectivamente. Ha reducao linear da taxa de biomassa com o incremento da dose de regulador de crescimento em aveia independente da condicao de ano e uso de N-fertilizante. No uso reduzido alto e muito alto de N-fertilizante, a dose de 495 mL ha-1 de regulador reduz com eficiencia o acamamento sem prejuizos na produtividade de graos de aveia, seja ano favoravel, intermediario ou desfavoravel ao cultivo.

Quantitative spectral reflectance data have the potential to improve the evaluation of turfgrasses in variety trials when management practices are factors in the testing of turf aesthetics and functionality. However, the practical application of this methodology has not been well developed. The objectives of this research were 1) to establish a relationship between spectral reflectance and turfgrass quality (TQ) and percent green cover (PGC) using selected reference plots; 2) to compare aesthetic performance (TQ, PGC, and vegetation indices) and functional performance (surface firmness); and 3) to evaluate lignin content as an alternate means to predict surface firmness in turfgrass variety trials of hybrid bermudagrass [Cynodon dactylon × C. transvaalensis]. A field study was conducted on mature stands of three varieties (‘TifTuf’, ‘TifSport’, and ‘Tifway’) and two experimental lines (04-47 and 04-76) at two mowing heights (0.5 and 1.5 inch) and trinexapac-ethyl application (0.15 kg·ha−1 and nontreated control) treatments. Aesthetic performance was estimated by vegetation indices, spectral reflectance, visual TQ, and PGC. The functional performance of each variety/line was measured through surface firmness and fiber analysis. Regression analyses were similar when using only reference plots or all the plots to determine the relationship between individual aesthetic characteristics. Experimental line 04-47 had lower density in Apr. 2010, whereas varieties ‘TifTuf’, ‘TifSport’, and ‘Tifway’ were in the top statistical group for aesthetic performance when differences were found. ‘TifSport’ and ‘Tifway’ produced the firmest surfaces, followed by ‘TifTuf’, and finally 04-76 and 04-47, which provided the least firm surface. Results of leaf fiber analysis were not correlated with turf surface firmness. This study indicates that incorporating quantitative measures of spectral reflectance could reduce time and improve precision of data collection as long as reference plots with adequate range of green cover are present in the trials.

Traffic stress is one of the major abiotic stresses that limits grass growth in lawn fields. The severity of losses depends on several factors, including the number of events per season, the athletic field size, and the soil moisture content during the traffic incident. Trinexapac-ethyl (TE) is considered to influence plant tolerance to traffic stress. Therefore, the physiological responses of the wheatgrass (Agropyron desertorum L.) and tall fescue (Festuca arundinacea L. cv. Rebel) species to different levels of TE and traffic stress were investigated. A factorial experiment including combination of TE application and traffic stress treatments was performed based on a randomized complete block design (RCBD) with three replications in 2014 and 2015. The treatments, including traffic stress (traffic and nontraffic stress) and TE at three levels (0, 0.25, and 0.5 kg·ha−1), were applied once every 3 weeks. The simulated traffic stress was imposed using a Brinkman traffic simulator (BTS). The results showed that traffic stress reduced the turf quality, relative water content (RWC), total chlorophyll content, and antioxidant activity and increased electrolyte leakage (EL), soluble sugar content (SSC), and malondialdehyde (MDA) in both species. Conversely, TE increased the turf quality, RWC, SSC, and total chlorophyll and resulted in less EL and MDA in both species. Furthermore, TE application increased the superoxide dismutase (SOD) (EC 1.15.1.1), ascorbate peroxidase (APX) (EC 1.11.1.11), and peroxidase (POD) (EC 1.111.1.7) activities, especially under traffic stress conditions. TE application enhanced the resistance to traffic stress in both species by improving the osmotic adjustment and antioxidant activity.

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.

Empresa Brasileira de Pesquisa Agropecuária -Embrapa Fundação Estadual de Pesquisa Agropecuária - Fepagro Saccharin sorghum crop has been gaining ground in the Brazilian biofuels market, due to the growing demand for renewable energy. In addition, it is a good alternative to compensate for the off-season of sugarcane (main ethanol raw material in Brazil), it can also use the same infrastructure as sugar cane plants. However, the crop still has some limitations on its production, such as high lodging rates due to its large size. In view of this, the present work aimed to evaluate the agronomic performance of two cultivars of saccharin sorghum submitted to trinexapac-ethyl growth reducer applications at different doses and application numbers. Also, the objective was to verify the physiological quality and viability of the use of seeds produced by sorghum plants that received the applications of the growth regulator. For this, two experiments were conducted, one in the field at the Federal Institute of Education, Science and Technology of Rio Grande do Sul, Ibirubá campus, in the agricultural years 2016/17 and 2017/18, conducted in a randomized block design, with four repetitions per treatment, involving a trifactorial model (2 x 6 x 2) with two cultivars of sorghum (BRS 506 and Fepagro 19), six doses of growth reducer, commercial product (0; 150; 300; 450, 600 and 750 mL.ha-1) and different application numbers (one V5 stage application - 5 expanded sheets, and two applications, one in V5 and one in V8 - 8 expanded sheets) totaling 24 treatments. Plant height, lodging percentage, leaf area index, relative leaf chlorophyll content, plant biomass, leaf and stem dry mass and Brix were determined. The application of trinexapaque-ethyl reduced the height and lodging of saccharin sorghum plants without affecting the green matter yield. The second experiment was conducted at the Didactic and Seed Research Laboratory of the Federal University of Santa Maria (UFSM) in 2017, using seeds from cultivar BRS 506 from the field experiment (2016/17 harvest), conducted in a completely randomized design, with eight replications per treatment, involving a factorial model (4 x 2) with four doses of growth reducer, commercial product (0; 150; 450 and 750 mL.ha-1) and two application times (stage V5, and V5 + V8) totaling eight treatments. One thousand seed mass tests, first germination test count, total germination, sand emergence, seedling length and dry mass, electrical conductivity and accelerated aging were applied. There was a decrease in the physiological quality of saccharin sorghum seeds from plants that received trinexapc-ethyl, mainly with the increase of the number of applications. A cultura do sorgo sacarino vem ganhando espaço no mercado brasileiro dos biocombustíveis, devido à crescente demanda por energias renováveis. Também, é uma boa alternativa para compensar o período de entressafra da cana-de-açúcar (principal matéria prima do etanol no Brasil), podendo ainda, utilizar a mesma infraestrutura das usinas de cana-de-açúcar. No entanto, a cultura ainda apresenta algumas limitações quanto a sua produção, como por exemplo, altos índices de acamamento, devido seu porte elevado. Frente a isso, a pesquisa teve por objetivo avaliar o desempenho agronômico de duas cultivares de sorgo sacarino submetidas a aplicações do redutor de crescimento trinexapaque-etílico em diferentes doses e números de aplicações. Também, objetivou-se verificar a qualidade fisiológica e viabilidade de uso de sementes produzidas pelas plantas de sorgo que receberam as aplicações do regulador de crescimento. Para isto, foram conduzidos dois experimentos, sendo um de campo no Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Sul, campus Ibirubá, nos anos agrícolas 2016/17 e 2017/18, conduzido em delineamento de blocos casualizados, com quatro repetições por tratamento, envolvendo um modelo trifatorial (2 x 6 x 2) com duas cultivares de sorgo sacarino (BRS 506 e Fepagro 19), seis doses do redutor de crescimento, produto comercial (0; 150; 300; 450, 600 e 750 mL.ha-1) e diferentes números de aplicações (uma aplicação em estágio V5 – 5 folhas expandidas, e duas aplicações, sendo uma em V5 e outra em V8 – 8 folhas expandidas) totalizando 24 tratamentos. Foi determinada a estatura das plantas, percentual de acamamento, índice de área foliar, teor relativo de clorofila nas folhas, biomassa das plantas, massa seca de folhas e colmos e Brix do caldo. A aplicação de trinexapaque-etílico ocasionou a redução da estatura e do acamamento de plantas de sorgo sacarino, sem afetar a produtividade de matéria verde. O segundo experimento foi conduzido no Laboratório Didático e de Pesquisa em Sementes da Universidade Federal de Santa Maria (UFSM) em 2017, utilizando-se sementes da cultivar BRS 506 oriundas do experimento de campo (safra 2016/17), realizado em delineamento inteiramente casualizado, com oito repetições por tratamento, envolvendo um modelo fatorial (4 x 2) com quatro doses do redutor de crescimento, produto comercial (0; 150; 450 e 750 mL.ha-1) e dois momentos de aplicação (estádio V5, e V5+V8) totalizando oito tratamentos. Aplicou-se os testes de massa de mil sementes, primeira contagem do teste de germinação, germinação total, emergência em areia, comprimento e massa seca de plântulas, condutividade elétrica e envelhecimento acelerado. Observou-se diminuição da qualidade fisiológica de sementes de sorgo sacarino oriundas de plantas que receberam trinexapaque-etílico, principalmente com o aumento do número de aplicações.

Growth regulators have been widely employed as maturation inducers in the sugarcane crop, as an agricultural strategy. However, the response of varieties to the use of these compounds has been poorly studied, mainly in cerrado (savannah-like biome) areas occupied by the crop. This study was carried out to examine the effects of trinexapac-ethyl on important morphological characteristics of sugarcane varieties. The experiment was set up as a randomized block design with a 4 × 2 factorial arrangement consisting of four varieties (RB83-5054, SP80-1816, RB96-6928, and RB85-5156) associated or unassociated with application of trinexapac-ethyl (375 g L-1 of the a.i. ha-1), with four replicates. The ripener was applied at 126, 178, and 228 days after planting (DAP) the first-cycle sugarcane, using the dose of 125 g L-1 a.i. ha-1 per application. Upon harvest, which occurred at 243 DAP, we determined the number of stalks per meter, weight of 30 stalks without top, internode length, number of internodes per stalk, and yield of sugarcane stalks. Ripener application increased the number of stalks in varieties RB96-6928 and RB83-5054 and the weight of 30 stalks in varieties RB96-6928 and RB83-5054 and SP80-1816; reduced internode length in varieties RB85-5156 and RB83-5054; and increased stalk yield per hectare in varieties RB96-6928 and RB83-5054, but did not increase the number of internodes per stalk in any of the tested varieties. The variables number of stalks, stalk weight, internode length, and stalk yield responded in a genotype-dependent manner to the application of trinexapac-ethyl.

Plant growth regulators are compounds applied on golf courses to control turfgrass height. This study compared Anuew (active ingredient prohexadione-calcium) and Primo Maxx (active ingredient trinexapac-ethyl) as plant growth regulators on a mixed-stand fairway of creeping bentgrass and annual bluegrass. Visual ratings and NDVI readings were taken as measures of canopy quality and colour on a weekly basis. Fresh weight and dry weight clipping collections were taken every 350 GDD as measures of plant biomass. Visual ratings and NDVI readings showed some significant differences between treatments and control. Clipping biomass (fresh weight and dry weight) showed significant differences between the control and the treatments but there were no significant differences between the two treatments. As the rate of application of Anuew increased, there was less clipping biomass. Anuew and Primo-Maxx performed similarly as they both effectively regulated the growth height of the mixed-stand fairway. Nufarm, Guelph Turfgrass Institute

Eucalyptus plants are sensitive to stress during their initial development, and water deficit is the most important one. Thus, the hormetic effect caused by the application of chemical products may be a factor that allows plants to tolerate such stresses. The objective of this study was to evaluate the effects of trinexapac-ethyl on the initial growth of Eucalyptus urophylla (Clone I-144), under water deficiency, at two application timings (before planting - BP; and after planting - AP). Two experiments were conducted simultaneously in a greenhouse for 74 days after planting (DAP) eucalyptus in 15 L pots. Treatments consisted of three trinexapac-ethyl doses (0.0, 30, and 60 g a.i. ha-1) and two water conditions (with and without water deficit). A complete randomized block design was used, in a 3 x 2 factorial arrangement, with five replications. At the BP application timing, trinexapac-ethyl was sprayed at 0 DAP, and at the AP timing, at 24 DAP. In both experiments, plant height, diameter, leaf area, dry matter, total relative chlorophyll content and gas-exchange were evaluated. There was a positive effect for the net CO2 assimilation rate at 27 and 40 DAP, for AP and BP, respectively. Eucalyptus plants, without water deficit, presented higher growth, regardless of the application timing. In conclusion, the application of trinexapac-ethyl before planting caused a positive effect on the height and diameter of eucalyptus; and the application timing influenced, in different ways, the evaluated characteristics, not having harmful effects on any of them. RESUMO: Plantas de eucalipto são sensíveis a estresses durante o desenvolvimento inicial, sendo a deficiência hídrica o mais importante entre eles. Assim, o efeito hormético ocasionado pela aplicação de produtos químicos pode ser um fator que proporcione às plantas tolerar esses estresses. Objetivou-se neste estudo avaliar o efeito de trinexapac-ethyl no crescimento inicial de Eucalyptus urophylla (Clone I-144) sob deficiência hídrica, em duas épocas de aplicação (antes do plantio - AP; e depois do plantio - DP). Dois experimentos foram conduzidos simultaneamente em casa de vegetação, durante 74 dias após o plantio (DAP) do eucalipto, em vasos de 15 L. Os tratamentos consistiram de três doses de trinexapac-ethyl (0,0, 30 e 60 g i.a. ha-1) e duas condições hídricas (com e sem deficiência hídrica). Foi utilizado delineamento casualizado em blocos, em esquema fatorial 3x2, com cinco repetições. Na época de aplicação AP, a pulverização de trinexapac-ethyl ocorreu aos 0 DAP, e na época DP, aos 24 DAP. Foram avaliados: altura das plantas, diâmetro, área foliar, massa seca, teor relativo de clorofila total e trocas gasosas. Houve efeito positivo para a taxa de assimilação líquida de CO2 aos 27 e 40 DAP, para as épocas DP e AP, respectivamente. As plantas de eucalipto na ausência de deficiência hídrica apresentaram maior crescimento, independentemente da época de aplicação. Conclui-se que a aplicação de trinexapac-ethyl antes do plantio proporcionou efeito positivo para a altura e o diâmetro do eucalipto. As épocas de aplicação influenciaram de formas distintas as características avaliadas, não havendo efeito prejudicial em nenhuma delas.

The objective of this study was to evaluate the quality of seeds and yield of winter wheat under different retardants application. The two years field trials on winter wheat were carried out in the Institute of Plant Protection - National Research Institute in Poznan (Poland). Treatments consisted of trinexapac-ethyl, chlormequat and prohexadione calcium applied in mixtures with paraffin oil adjuvant or organosilicone surfactant in BBCH 31 growth stage of winter wheat. No lodging occurred in any experimental year. The retardants had varying effect on the quality parameters of wheat grain. The highest fluctuations in the content of protein, gluten and the Zeleny value were observed after the application of chlormequat chloride. Starch content in wheat grain, regardless of the retardant application method, was negatively correlated with others grain quality parameters evaluated in the experiment. Depending on the year of study and weather conditions, increased or decreased wheat quality. RESUMO: O objetivo deste estudo foi avaliar o tamanho e a qualidade do grão de trigo de inverno em condições de aplicação de diferentes retardadores e a possibilidade de os combinar com adjuvantes e herbicidas. Durante dois anos, o Instituto de Proteção de Plantas - Instituto Nacional de Pesquisa em Poznań (Polônia) realizou ensaios no campo de trigo de inverno. Os tratamentos consistiram em: trinexapac-etil ou clormequat ou prohexadiona-cálcio, aplicados em misturas com óleo adjuvante ou surfactante organossilicone na fase BBCH 31. Não se observou acamamento de plantas em nenhum ano dos ensaios. Os retardadores apresentaram efeitos variados sobre os parâmetros de qualidade do grão de trigo. As maiores variações no teor de proteínas, glúten e no índice de Zeleny foram observadas após a aplicação de clormequat. O teor de amido no grão, independentemente do retardador utilizado e do modo da sua aplicação, foi negativamente correlacionado com outros parâmetros de qualidade avaliados nos ensaios. Dependendo do ano de estudos, aumentava ou reduzia a qualidade do grão.

Trinexapac-ethyl is a popular plant growth regulator used in various crops, mostly due to its unique anti-lodging properties. Recently it has been found that this substance is also active in stress protection, which may increase its importance in the coming years. This paper presents a new approach to its application. Trinexapac-ethyl belongs to the cyclohexanedione class of herbicide chemistry, thus it is structurally similar to common graminicides frequently used with adjuvants. This study examines the effects of the application of trinexapac-ethyl with adjuvants. Field trials were conducted in the Institute of Plant Protection in Poznań (Poland), in 2014 and 2015. Trinexapac-ethyl was applied at recommended (0.4l・ha-1) and reduced doses (0.2l・ha-1) with organosilicone surfactant, ammonium sulphate and citric acid on spring barley. Stem shortening, yield components and grain quality were examined. The results of the study confirmed the possibility of dose reduction of trinexapac-ethyl by way of combined application with citric acid that reduced the pH of spray liquid or with ammonium sulphate without affecting its effectiveness. The greatest stem height reduction was observed after the application of a full dose of trinaxapac ethyl and its reduced dose in the mixture with citric acid or ammonium sulphate. Depending on the year of study, the effectiveness of the substances on stem reduction ranged from 5.6 to 16.5%. The tested mixtures did not have any significant impact on the number of grains per ear or the yield of spring barley. Trinexapac-ethyl and its mixtures with adjuvants did not influence the crude protein and starch in spring barley grains.

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.

Methods Two plantings (2011 and 2012) of red clover seed crops were established in the fall at Hyslop Crop Science Research Farm near Corvallis, and each has been followed over a two-year period to examine the effects of irrigation and PGRs. PGR treatment subplots (11 feet x 50 feet) were randomly allocated within irrigated and non-irrigated main plots in a split-plot arrangement of treatments in a randomized block experimental design. Trials were replicated in four blocks. The TE PGR treatments were made on the subplots at two application timings and at five rates of TE. Control plots were not treated (Table 1).

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

This study aimed to evaluate the effect of sequential applications of plant regulators on growth and seedhead emergence of Bahiagrass (Paspalum notatum). The study was carried out on a 15-month-old lawn, in a randomized block design, with four replicates. The treatments consisted of the following plant-growth regulators and dose: trinexapac-ethyl in sequential application of 113 + 113, 226 + 113, 226 + 226, 452 + 113, 452 + 226, 452 + 452 g a.i. ha-1; trinexapac-ethyl in single application of 678 and 904 g a.i. ha-1; and prohexadione-calcium in sequential application of 100 + 100 and 200 + 200 g a.i. ha-1, besides a control, with no application. The effects of treatments were evaluated based on visual injury, plant height, height and number of flower rachises and total dry matter production of clippings. Sequential applications of prohexadione-calcium at 100 + 100 or 200 + 200 g a.i. ha-1 were efficient to reduce plant height, but did not show efficacy to reduce the number and height of seedheads or the total dry matter of clippings of Bahiagrass. However, Bahiagrass lawns can be managed by trinexapac-ethyl sequential applications of 452 + 452 g a.i. ha-1 or single application of 904 g a.i. ha-1, with reduction in the need for mowing for a period of up to 113 days after application, without causing any deleterious effect on the visual aspect of the lawn. RESUMO Este trabalho teve o propósito de avaliar o efeito da aplicação sequencial de reguladores vegetais sobre o crescimento e a emissão de hastes florais da grama-batatais (Paspalum notatum). O estudo foi instalado em um gramado com 15 meses, no delineamento de blocos casualizados, com quatro repetições; utilizaram-se os seguintes inibidores de desenvolvimento vegetativo: trinexapac-ethyl em aplicações sequenciais de 113 + 113, 226 + 113, 226 + 226, 452 + 113, 452 + 226 e 452 + 452 g ia ha-1, trinexapac-ethyl em aplicação única a 678 e 904 g ia ha-1 e prohexadione-calcium em aplicações sequenciais nas doses de 100 + 100 e 200 + 200 g ia ha-1, além de um controle sem aplicação dos produtos. O efeito dos tratamentos foi avaliado quanto à injúria visual, altura de plantas, altura e emissão de hastes florais e produção de matéria seca de aparas. As aplicações sequenciais de prohexadione-calcium, independente da dose testada, foram efetivas na redução da altura de plantas mas não apresentaram eficiência na redução do número e altura de inflorescências nem na quantidade total de matéria seca produzida pela grama-batatais; entretanto, gramados formados com a grama-batatais podem ser manejados com o trinexapac-ethyl em aplicação sequencial de 452 + 452 g ha-1 ou em aplicação única na dose de 904 g ha-1, com a redução da necessidade de cortes por um período de até 113 dias após a aplicação sem que ocorra efeito deletério no aspecto visual sobre o gramado.

During water conservation periods, municipal water purveyors often limit irrigation for established lawns to once every 7 to 14 days, although a 4- to 6-week variance to these restrictions is often permitted for turfgrass establishment. Therefore, establishment practices promoting rapid development of a deep and expansive root system during this time may support long-term success of the turf once irrigation is scaled back. Sod producers and turf managers could benefit from information on the influence of mowing practices and plant growth regulator (PGR) applications on turf root development during this initial establishment period. The objectives of this greenhouse study were to 1) evaluate the effects of mowing and trinexapac-ethyl (TE) application on final turf quality and root development characteristics (weight, total length, and extension rate) of st. augustinegrass (Stenotaphrum secundatum) sod during a 35-day establishment period, and 2) compare the quality and rooting potential of ‘TamStar’, a newly released, embryo-rescue-derived cultivar possessing good drought resistance, with ‘Floratam’, the current industry standard for drought resistance. Weekly mowing reduced both total (2.5 to 90 cm) and deep (45 to 90 cm) root weight and root length in both cultivars. TE had no effect on visual quality of ‘TamStar’, but decreased turf quality in ‘Floratam’. TE reduced clipping yields of both cultivars but did not improve root development for either cultivar. Depth of maximal root extension during establishment was unaffected by cultivar, mowing, or TE treatment. At the conclusion of the 35-day establishment period, ‘TamStar’ exhibited superior turf quality and root weight relative to ‘Floratam’, but also produced higher rates of shoot growth. Results emphasize the importance of withholding mowing during st. augustinegrass establishment, particularly for improving total root length and deep root production, and also show that TE does not improve root development of st. augustinegrass during establishment.

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.

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. ABSTRACT The production of oat biomass focused on the development of quality silage is dependent on climatic elements and nitrogen without lodging occurrence. The objective of the study is to define the optimal dose of growth regulator that allows a maximum of 5% oat plant lodging and identify potential variables for composition of multiple linear regression model with productivity simulation of biomass to the preparation of silage in the conditions of low, high and very high fertilization with nitrogen. The study was conducted in 2013, 2014, and 2015 in the randomized block design with four replications in a factorial 4x3, for regulator doses (0, 200, 400 and 600ml ha-1) and nitrogen doses (30, 90 and 150kg ha-1), respectively. The dose of 495mL ha-1 regulator is efficient in reducing the oat plant lodging in condition reduced, high, and very high fertilization with nitrogen. Thermal time, precipitation, radiation, regulator dose and nitrogen dose qualify the composition of the multiple linear regression model, making efficient the biomass oat productivity simulation for silage over the cycle.

The aim of this study was to assess the effect of the growth retardant trinexapac-ethyl on the physiological quality of seeds of different grain white oat cultivars in two growing environments. The experiments were carried out in Londrina and Mauá da Serra, Paraná State, Brazil. The experimental design was a randomized block design in a 4 × 2 factorial scheme with four replications. Treatments consisted of four white oat cultivars (IPR Afrodite, IPR Artemis, URS Corona, and URS Guria), with and without growth retardant application. Trinexapac-ethyl was applied by foliar spraying in a dose of 125 g a.i. ha−1 at the stem elongation stage between the first and second perceptible node. The following parameters were assessed: germination, first germination count, length and dry matter of seedling shoot and root, accelerated aging, electrical conductivity, emergence rate index, seedling emergence in sand, one-thousand-seed weight. At the end of the study, Londrina and Mauá da Serra presented a production potential white oat seed with germination above the standards for the species. Trinexapac-ethyl application reduced seed vigor of the cultivars IPR Afrodite and IPR Artemis produced in Londrina and Mauá da Serra, respectively.

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

Summary Compact and well branched ornamental peppers are commercially preferred. Plant growth regulators (PGR) and pinching, removal of shoot apices, are used to create ornamentals with high aesthetic value. Trinexapac-ethyl (TE) is a foliarly absorbed plant growth regulator (PGR) and belongs to acylcyclohexadione chemical family that inhibits gibberellic acid biosynthesis. The objective of this study was to investigate possibility of using TE as a PGR in ornamental pepper (Capsicum annuum L.) production to suppress vertical growth and/or substitute for pinching to produce more compact and quality plants. The 0, 2, 4, 8, and 12 ppm TE was foliarly applied onto either pinched or non-pinched plants. Pinching and TE reduced the canopy height up to 25% and 38%, respectively. TE along with pinching reduced Height/ Diameter (H/D) ratio from 2.3 down to 1.5, a more commercially desired compactness. TE increased the chlorophyll content and total fruit number. TE may substitute costly pinching treatment for growth control. The absence of phytotoxicity and improved production may justify recommendation of TE for commercial ornamental pepper production.

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.

RESUMO Reguladores de crescimento podem ser utilizados com o intuito de evitar o acamamento do trigo, porém, podem apresentar outros benefícios, em função da melhoria da interceptação de luz e da realocação de carbono. O objetivo deste trabalho foi avaliar a influência do regulador de crescimento (trinexapac-etil) sobre o desenvolvimento vegetativo, os componentes da produção e a qualidade de grãos de dois cultivares de trigo distintos em relação à susceptibilidade ao acamamento. Um experimento foi realizado em casa de vegetação e outro a campo. No experimento em casa de vegetação, foram avaliadas as variáveis de desenvolvimento vegetativo (estatura de planta, relação entre raiz e parte aérea, áreas foliares unitária e total, comprimento e matéria seca de raízes) em plantas de trigo, com e sem a aplicação de trinexapac-etil, em estádio de primeiro nó visível e segundo nó perceptível. A campo foram avaliadas variáveis de desenvolvimento vegetativo (clorofila, estatura e área foliar), rendimento (número de espigas, massa de mil grãos e produtividade) e qualidade (massa do hectolitro e conteúdo de proteína), em plantas de trigo com variações de aplicação de trinexapac-etil (testemunha sem aplicação, perfilhamento e primeiro nó visível e segundo perceptível). O regulador de crescimento trinexapac-etil aumenta a relação entre raiz e parte aérea do cultivar Mirante e a produtividade dos cultivares Quartzo e Mirante. Porém, não interfere na qualidade de grãos desses cultivares. ABSTRACT Growth regulators could be used to avoid wheat lodging, however may show advantages due to increase in solar radiation intercepted and carbon reallocation. The aim of this work was to evaluate the influence of a growth regulator (trinexapac-ethyl) on vegetative development, production components and grain quality of two wheat cultivars distinct in lodging. An experiment was done in greenhouse and another at field. In greenhouse were evaluated vegetative development variables (plant stature, leaf area, ratio root:shoot, length and dry mass of roots) in wheat plants with and without application of trinexapac-ethyl on first node visible and second node noticeable. At field were evaluated vegetative development, yield and quality grain variables (hectoliter mass and protein content) in wheat plants with variations of trinexapac-ethyl applications (untreated control, tillering and first node visible and second node noticeable). The growth regulator trinexapac-ethyl increases the ratio root:shoot in Mirante cultivar and increases the yield in Quartzo and Mirante cultivars. However, using the growth regulator, there is no interference in the grain quality of these cultivars.

Improving abiotic stress tolerance in plants by crop management is one of biggest goals of actual research, thus, plant growth regulators have a great potential in the physiological manure of crops. The objective of this work was to evaluate the effects of Trinexapac-Ethyl on soybean plants affected by drought stress during the reproductive stage. Four Trinexapac-Ethyl doses were evaluated (0, 50, 100, and 200 g ha-1 a.i.) and the induction or not of drought stress. The experimental design was completely randomized blocks in factorial design (4x2) with four replications. Relative water content was measured during drought stress and rehydration period. Protoplasmic tolerance and biometric parameters were determined after recovery period. Yield and yield components were determined at the end of crop cycle. Low intensity drought stress was verified at this work, which affected the plant growth but did not affect soybean yield. Trinexapac-Ethyl application resulted in maintenance of leaves relative water content, mainly at 200 g ha-1 dose, without affect biometric parameters and grain yield. This behavior is a great indicative of increase in soybean drought tolerance.

Interspecific hybrids between texas bluegrass (Poa arachnifera Torr.) and kentucky bluegrass (Poa pratensis L.) are known to exhibit good heat tolerance, which has aided in their adaptation to the warmer climates of the southern United States, but their tolerance to shade has not been investigated. The objectives of this study were to 1) evaluate the growth responses of interspecific bluegrass hybrids (P. arachnifera × P. pratensis) in comparison with kentucky bluegrasses and a shade-tolerant cultivar of tall fescue (Festuca arundinacea Schreb.) under full sunlight and shaded environments, 2) identify optimum times to evaluate shade tolerance using the selected growth measurements, 3) calculate the minimum daily light requirements to retain acceptable turfgrass quality, and 4) determine if trinexapac-ethyl (TE) applications enhance hybrid bluegrass quality under shade. Two 10-week greenhouse experiments (late spring and early fall) were conducted in Dallas, TX. Within each of three light environments a randomized complete block design was used to accommodate three replications of eight genotypes treated with and without TE (0 or 0.228 kg·ha−1 a.i.). Turfgrass quality, leaf elongation rates, clipping dry weights, and percent green cover were measured. Meaningful comparisons were best during the late spring when daily light integrals (DLI) were optimum for healthy plant growth. Shade-tolerant hybrid bluegrasses (DALBG 1201 and TAES 5654) were identified using turfgrass quality and leaf elongation rates. These genotypes exhibited above-acceptable turfgrass quality in all environments, and a reduced leaf elongation rate similar to the tested dwarf-type tall fescue. DLI requirements of DALBG 1201 and TAES 5654 were ≤4 to achieve acceptable quality. TE applications generally did not improve turfgrass quality of genotypes, although leaf elongation rates were significantly reduced in all environments.

As the need for landscape and golf course water conservation increases, use of low-quality irrigation water combined with deficit irrigation practices is becoming more common. Information is lacking concerning the effects of water quality on bermudagrass response to deficit irrigation, as well as the extent to which plant growth regulators may ameliorate or delay the negative effects of water stress on warm-season turfgrass. The objectives of this 10-week greenhouse study were to 1) characterize growth, quality, and evapotranspiration (ET) of ‘Tifway’ bermudagrass (Cynodon dactylon × C. traansvalensis Burt Davy) when irrigated at full (1.0 × ETa) or deficit (0.3 × ETa) levels of actual turfgrass evapotranspiration (ETa) using three irrigation water sources [reverse osmosis (RO), sodic potable, and saline] and 2) determine whether application of trinexapac-ethyl (TE) could mitigate turfgrass quality decline under deficit irrigation. Results indicated that turf irrigated with sodic irrigation water exhibited significantly elevated ETa and shoot growth compared with turf receiving RO or saline irrigation water in both studies. Irrigation water source affected turfgrass quality differently at each irrigation level. TE application improved turfgrass quality and/or delayed firing under soil moisture stress in both studies, with the greatest benefit noted under the less intense conditions of the spring experiment. Elevated canopy temperatures were observed within all deficit irrigation treatments, regardless of water chemistry. Results demonstrate that irrigation water quality may influence turfgrass ET rates. In addition, they suggest that trinexapac-ethyl may offer short-term mitigation of drought stress under deficit irrigation.

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.