Nativa, Sinop, v. 10, n. 1, p. 16-21, 2022.

Pesquisas Agrárias e Ambientais

DOI: https://doi.org/10.31413/nativa.v10i1.12749 ISSN: 2318-7670

Management of trinexapac-ethyl application in soybean

Isabela Letícia SOUZA1, Tiago Roque Benetoli da SILVA1*,

Leandro Paiola ALBRECHT1

1State University of Maringá, PR, Brazil.

*E-mail: trbsilva@uem.br

(ORCID: 0000-0002-8907-4430; 0000-0002-2015-2103; 0000-0003-3512-6597)

Recebido em 13/07/2021; Aceito em 31/01/2022; Publicado em 14/03/2022.

ABSTRACT: This work aimed to evaluate the effects of using management of growth regulator trinexapac-

ethyl (Moddus®)) over plant height, lodging, productivity and grain yield of soybean plants (Glycine max (L.)

Merrill. cv. BS 2606 IPRO). For that, an experiment was installed in field conditions, by using a randomized

block design, with four replications; experimental unit was constituted of five lines of four meters in length,

spaced at 0.45 m. Treatments were constituted by the application of growth regulator, as follows: without

application; total dose between V3 and V4; total dose between V5 and V6; ½ dose between V3 and V4 + ½

dose between V5 and V6; total dose between V3 and V4 + total dose between V5 and V6, totaling five

treatments. Productive components, mass of 100 grains and grain yield were evaluated. Results were not

significant for studied variables regardless of management, differing only from the control.

Keywords: oilseed; lodging; plant regulator; application management; grain yield.

Manejo da aplicação de trinexapac-ethyl na soja

RESUMO: Esse trabalho teve por objetivo avaliar os efeitos da utilização de manejos do regulador de

crescimento (trinexapac-ethyl (Moddus®)) sobre altura, acamamento, produtividade e rendimento de plantas de

soja (Glycine max (L.) Merrill. cv. BS 2606 IPRO). Com isso, instalou-se um experimento em condições de

campo, com o delineamento experimental de blocos casualizados, com quatro repetições; a unidade

experimental constituiu-se de cinco linhas de quatro metros de comprimento, espaçadas em 0,45 m entre elas.

Os tratamentos foram constituídos pela aplicação do regulador de crescimento, sendo: sem aplicação; dose total

entre V3 e V4; dose total entre V5 e V6; ½ dose entre V3 e V4 + ½ dose entre V5 e V6; dose total entre V3 e

V4 + dose total entre V5 e V6, perfazendo cinco tratamentos. Foram avaliados os componentes produtivos,

massa de 100 grãos e produtividade. Os resultados não foram estatisticamente significativos para as variáveis

avaliadas independente dos manejos, diferindo apenas da testemunha.

Palavras-chave: oleaginosa; acamamento; regulador vegetal; manejo de aplicação; produtividade.

1. INTRODUCTION

Soy is the main grain crop in the country, and in the

2020/21 harvest approximately 38.47 million hectares were

cultivated, with an estimated production of 135.5 million

tons, which makes Brazil not only the largest producer, but

also the world's largest exporter (CONAB, 2021).

New technologies are constantly being sought to increase

the productivity of soybean crops, which avoid losses in grain

yield and allow its adaptation to different climate change

scenarios. In this sense, the causes of yield losses are diverse

and occur both before, during and after harvest

(AINSWORTH et al., 2008; VARSHNEY et al., 2011;

PRATAP et al., 2012).

Lodging is positively correlated with plant height and can

seriously damage production, causing yield losses in soybean

cultivars, around 10% (SHERRIE et al., 2011). Under

conditions that provide high vegetative development of

soybean, plants become highly susceptible to lodging. With

it, there is the shading of the leaves that previously received

full radiation, causing disorganization of the canopy

(MUNDSTOK; THOMAS, 2005). Shaded leaves, with less

radiation interception, have a higher

respiration/photosynthesis ratio than those with good sun

exposure, and can become photoassimilated drains, which

can reduce the productive capacity of plants. Lodging also

influences the morphological structure essential for the

efficient use of carbohydrates and their translocation to the

grain, and the earlier it occurs, the greater the reduction in

grain yield and quality (ZANATTA; OERLECKE, 1991;

ROCHA, 1996; LAWN; JAMES, 2011).

The reduction in grain quality occurs from deterioration,

which is facilitated by increasing proximity to the soil

(LOBATO, 2006). Two strategies are presented to solve the

lodging problem in soybean: the use of cultivars with

resistance to lodging (Lawn; James, 2011) and the use of plant

regulators (BUZZELLO et al., 2013). As cultivars that

present resistance to lodging do not always have high

productive potential under certain environmental conditions,

the use of growth regulators cannot be ruled out.

Plant growth regulators or phytoregulators are all

chemical compounds that decrease cell division and

elongation in meristematic tissues and physiologically

regulate plant height (CATHEY, 1964). Synthetic

compounds can be used to reduce unwanted longitudinal

growth of plant shoots without decreasing grain yield

(RADEMACHER, 2000). Phytoregulators are compounds

Souza et al.

Nativa, Sinop, v. 10, n. 1, p. 16-21, 2022.

used in low concentrations, whose response can be either

stimulatory or inhibitory on plant development processes

(VIEIRA; CASTRO, 2004).

According to Campos et al. (2008), plant regulators

influence the response of many plant organs, but this

response depends on the species, plant part, development

stage, concentration, interaction between other regulators

and various environmental factors.

Plant growth regulators such as gibberellins biosynthesis

inhibitors provide a reduction in plant size and this implies

the targeting of metabolics to their reproductive structures

(NÓBREGA et al., 1999). According to Fernandez et al.

(1991), the application of the plant growth regulator

(mepiquat chloride) affects the plant promoting the balance

between the vegetative and reproductive parts, which can

also be observed in the present study with the trinexapac-

ethyl regulator.

The action of trinexapac occurs in the synthesis of

gibberellins, which acts by deregulating the levels of active

gibberellic acid (GA1), strongly increasing the levels of its

biosynthetic precursor (GA20), which is found in conjugated

form and is not active (NAKAYAMA et al. al., 1990).

Through this, it cannot synthesize active gibberellins, so

plants begin to synthesize and accumulate less efficient

gibberellins, causing reductions in cell elongation

(RADEMACHER, 2000; Taiz and Zeiger, 2006). The main

gibberellin associated with stem elongation and activity in

reproductive buds of several species is GA1, mainly from

monocots (PERES; KERBAUY, 2004). The likely cause of

plant growth inhibition is a drop in the level of active

gibberellic acid (GA1) (WEILER; ADAMS, 1991;

RADEMACHER, 2000). This inhibition is not as strong in

dicots such as soybeans, thus justifying the selectivity of

trinexapac for plants in this group.

Rademacher (2000) and Rodrigues et al. (2003), state that,

generally, growth reducers have an antagonistic action to

gibberellins and act by modifying their metabolism. The use

of growth regulators obtains an interesting result, in which

there is a reduction in plant height, in the sense of increasing

the tolerance of plants to lodging, however, it does not

reduce grain yield (SOUZA et al., 2013). Campos et al. (2010)

also mention that, with the use of plant regulators, plants

become more compact and thus more efficient from a

physiological point of view. In the case of plant growth

reducers, these are used to make the plant architecture more

adapted and efficient in the use of environmental resources

and inputs to achieve maximum agronomic yield (SOUZA et

al., 2013).

In the case of soy, when working with plant regulators,

its ability to provide development or avoid production

limitations is plausible, however, significant increases in

productivity may not occur, as other factors (humidity,

temperature and radiation) can be severely limiting

(CASTRO, 1980). The effect generated by the growth

reducer depends on several factors, including: the dose used,

the application and sowing time, the environmental

conditions, the nutritional and phytosanitary status of the

plant (RODRIGUES et al., 2003).

In this context, this work aimed to evaluate the effects of

the use of growth regulator management (trinexapac-ethyl)

on height, lodging and yield of soybean plants.

2. MATERIAL AND METHODS

The experiment was carried out at Fazenda Santa

Terezinha, in the municipality of Tuneiras do Oeste, Paraná

State, at the geographic coordinates 23° 50' 60'' S and 52° 52'

10'' W, at an altitude of 483 m. The region has a

predominantly Cfa or subtropical climate, with hot summer,

according to the Köppen classification (IAPAR, 2014). Table

1 shows the climate data during the entire experimental

period, which began on October 22, 2019 and ended on

March 6, 2020, obtaining a maximum temperature of 39°C

and a minimum of 14°C, relative humidity of 79 % and total

precipitation of 801.5 mm in a total of 36 days with rain.

Table 1. Climatic data during the entire experimental period

(10/22/2019 to 03/06/2020), Tuneiras d'Oeste (PR) - 2019/20.

Tabela 1. Dados climáticos durante o período experimental

(10/22/2019 até 03/06/2020), Tuneiras d'Oeste (PR) - 2019/20.

Lowest minimum

temperature

14 °C

Highest maximum

temperature

39 °C

Total precipitation

801.5 mm

Rainfall average

22.26 mm

Average precipitation per

day/period

6.03 mm

Medium humidity

79%

Number of days with rain

36 days

Source: Coamo Cooperative Weather Station, headquartered in Moreira

Sales-PR

The soil in the area is classified as Dystrophic Red

Latosol (EMBRAPA, 2018) with a sandy texture. Before the

installation of the experiment, chemical and granulometric

analysis of the soil was carried out at a depth of 0.0-0.20 m,

shown in Table 2. The experiment was installed in soil with

13% clay, 7% silt, 80% of sand, pH (CaCl2) 4.58 and organic

matter of 8.69 g dm-3. This area had previously been

cultivated with Brachiaria ruziziensis.

Table 2. Chemical attributes of the soil at the site before the

implementation of the experiment, in the 0-20 cm layer.

Tabela 2. Características químicas do solo antes da implantação do

experimento, coletada na camada de 0-20 cm de profundidade.

M.O.

CTC

CaCl

dm-3

g dm

--------------------

cmol

-3

------------

--------

4,58

13,67

8,69

1,70

0,23

0,72

0,2

6,02

44,1

P and K extracted with resin; Organic matter extracted by the Walkley-Black

method; Ca, Mg and Al extracted with KCl 1 cmol L-1.

The experiment was carried out under field conditions,

with the experimental design of randomized blocks, with four

replications; the experimental unit consisted of five lines of

four meters in length, spaced 0.45 m between them,

considering as useful area the three central lines, totaling 4.05

m2 of useful area, disregarding 0.5 m of both the ends.

The base fertilization was carried out using 300 kg ha-1

of 04-30-10, based on the soil analysis and recommendation

of Pauletti and Motta (2017). The soybean cultivar used in

the experiment was BS 2606 IPRO, with characteristics such

as medium size, indeterminate growth, root aggressiveness,

tolerance in periods of water stress and to the root rot

complex. Maturation group 6.0 and planting time and plant

population recommendations are from October 1st to

November 20th and 240 thousand plants ha-1, respectively.

Management of trinexapac-ethyl application in soybean

Nativa, Sinop, v. 10, n. 1, p. 16-21, 2022.

The treatments were constituted with the application of

the trinexapac-ethyl growth regulator (Moddus®), based on

recommended doses for wheat and barley, considering 0.5 L

ha-1 of the commercial product, as follows: without

application; total dose between V3 and V4; total dose

between V5 and V6; ½ dose between V3 and V4 + ½ dose

between V5 and V6; total dose between V3 and V4 + total

dose between V5 and V6, making up five treatments.

During the experiment, the necessary cultural treatments

were carried out to keep the area free of weeds, pests and

diseases, throughout the development of the culture. Sowing

was carried out on October 22, 2019 and harvesting on

March 6, 2020, manually, in the useful area of each

experimental plot after desiccation.

The variables evaluated were: yield components (number

of pods per plant, number of grains per plant, number of

grains per pod), weight of 100 grains, plant height and yield.

To determine the productive components, ten plants

were collected at harvest. Afterwards, the pods were counted

and threshed and the grains counted, determining the

number of grains per plant, grains per pod and pods per

plant.

For productivity in kg ha-1, plants were harvested from

the useful area of each experimental plot, with threshing of

the pods and weighing. The grains were separated to

determine the mass of one hundred grains, by weighing two

subsamples for each repetition used. Both assessments were

standardized at 13% moisture (BRASIL, 2009).

Data were subjected to analysis of variance at a 5%

probability level. The means were compared using the Tukey

test at the same level of significance, using the Sisvar program

(FERREIRA, 2011).

3. RESULTS

The application of the growth regulator increased the

number of pods/plant and number of grains/plant,

compared to plants without application (Table 3). On the

other hand, application times and doses did not differ from

each other.

The application of the growth regulator also did not

affect the final plant population and mass of 100 grains,

compared to plants without application (Table 4). However,

it reduced plant height and increased productivity.

4. DISCUSSION

After applications of growth regulators, which inhibit the

synthesis of gibberellin, plants may show an increase in the

number of pods (HERTWIG, 1992). Zagonel et al. (2002)

point out that plants with smaller height and more compact

present better direction of the photoassimilates, increasing

the number of reproductive structures per meter.

Crotalaria is influenced by growth regulators, both in its

vegetative and reproductive development. In an experiment

carried out by Freis et al. (2011) the increase in the doses of

trinexapac-ethyl and paclobutrazol provided a greater

number of pods and seeds per plant, compared to mepiquat

chloride. Thus, as noted in the experiment by Novakoski et

al. (2020), the application of post-emergence herbicides, such

as lactofen (36 g ai ha−1) or chloransulam (33.6 g ai ha−1) on

soybean (V3-V4), can also regulate plant height and not have

a negative effect on the productive components of soybean.

Linzmeyer Junior et al. (2008) observed that there was no

effect of trinexapac-ethyl doses on the number of pods per

plant in soybean. However, under similar study conditions,

Nascimento et al. (2009) tested the application of five doses

of trinexapac-ethyl growth regulator in upland rice, and

obtained a positive response from the application of

trinexapac growth regulator on grain yield, at a dose of 150 g

ha-1 of ai, applied in the floral differentiation of the Primavera

rice cultivar.

Table 3. Number of pods per plant, number of grains per plant and

number of grains per soybean pod, as a function of the application

of plant regulator. Tuneiras d'Oeste (PR) – 2019/20.

Table 3. Número de vagens por planta, grão por planta e grãos por

vagem de soja, em função da aplicação de regulador vegetal.

Tuneiras d'Oeste (PR) – 2019/20.

Treatment

Pod plant

-1

Grain plant

-1

Grain pod

-1

application

43.8 b

99 b

2.26

–

V4 (E1)

54.9 a

125 a

2.27

–

V6 (E2)

55.3 a

126 a

2.27

½(E1)+½(E)

56.7 a

130 a

2.29

E1 + E2

57.8 a

131 a

2.26

CV (%)

7.8

8.9

3.5

Test F

n.s.

E = season

n.s and * = not significant and significant at 5% probability of error.

Means followed by the same letter in the column do not differ by Tukey test

at 5% probability of error.

CV = coefficient of variation

Table 4. Plant height (cm), final plant population, weight of 100

grains (g) and yield (kg ha-1) soybean, as a function of plant growth

regulator application. Tuneiras d'Oeste (PR) - 2019/20.

Table 4. Altura de plantas (cm), população final de plantas, massa

de 100 grãos (g) e produtividade (kg ha-1) de soja, em função da

aplicação de regulador vegetal. Tuneiras d'Oeste (PR) – 2019/20.

Treatment

Plant

height

(cm)

Final

population

of plants

100 grain

mass

(grams)

Productivity

(kg ha-1)

application

1,42 a

219.444

16,5

3.119 b

–

V4 (E1)

1,24 b

241.667

16,0

3.793 a

–

V6 (E2)

1,22 b

219.444

16,2

3.783 a

½(E1)+½(E)

1,26 b

258.333

16,1

3.859 a

E1 + E2

1,25 b

225.000

16,7

4.088 a

CV (%)

3,5

12,3

4,8

13,8

Test F

n.s.

E = season

n.s and * = not significant and significant at 5% probability of error.

Means followed by the same letter in the column do not differ by Tukey test

at 5% probability of error.

CV = coefficient of variation

The application of the growth regulator also did not

affect the number of grains per pod (Table 3), as this

characteristic is related to the genetic aspects of the highly

heritable plant, not being much influenced by the

environment or by exogenous factors (FREIRE et al., 2007).

The number of grains per pod is not a character influenced

by phytotechnical management practices, it is determined by

the genotype itself (KAPPES et al., 2011). Maize seed mass

is the productive component least affected by variations in

management practices (SANGOI et al. 2002)

Chavarria et al. (2015), evaluating wheat yield

components in the field, did not observe significant

differences when trinexapac was applied in relation to the

number of grains per ear. In an experiment in which growth

Souza et al.

Nativa, Sinop, v. 10, n. 1, p. 16-21, 2022.

regulators were applied to soybean, Souza et al. (2013) also

did not observe the influence of the reducers on the number

of grains per pod. Using the same regulator in soybeans, it

was verified that plant dry mass, leaf area, production

components and yield were not affected by the use of this

plant growth reducer (LINZMEYER JUNIOR et al., 2008).

Trinexapac is an acylcyclohexanedione (Caldas et al.,

2009; Rademacher, 2000) which, in Poaceae, such as wheat

and rye, causes a reduction in node interlength and,

consequently, in plant height. It is used to reduce plant

lodging (MAPA, 2011; Espindula et al., 2009), but with no

negative effect on grain yield (ZAGONEL; FERNANDES,

2007).

The results of this work corroborate those of Linzmeyer

Junior et al. (2008), in which the application of the plant

retardant directly influenced the height of soybean plants,

with a decreasing linear effect for plant height when applying

the retardant and the density of plants used. Similar results

were obtained by Alvarez (2003), who, using trinexapac in

rice cultivation, observed a reduction in plant height of up to

34 cm.

Zagonel (2007) found that wheat cultivars responded

linearly to the dose of trinexapac, decreasing height with

increasing dose of the reducer, except for the cultivar Onix,

a result that corroborates other studies (Zagonel, 2003;

Zagonel et al., 2005; Zagonel; Kunz, 2005), showing that the

product is effective in reducing the height of wheat plants.

The final plant population depends on several factors,

which include climatic conditions in the initial periods of

crop development and the cultivars used. Plant density

(cultivated and weeds) and even the positioning of the

fertilizer distributed by the seeder can influence the

development of the root system of cultivated plants. In

addition to the processes involved in shoot growth,

gibberellins are involved in root system stimulation and

growth processes (BEVILAQUA et al., 1996). Thus, the non-

significant result for this variable is explained.

In the present work, it was observed that the mass of 100

grains was not significantly affected by the treatments,

however, the yield was significant (Table 4). Unlike the result

of this work, Linzmeyer Junior et al. (2008) verified that the

application of trinexapac-ethyl (100 g ha-1) in bean plants,

cultivar Pérola, did not affect seed mass, number of seeds per

plant, number of pods per plant and number of seeds per

pod.

The increase in productivity was also noticed in the

present experiment with the use of the growth regulator.

According to Zagonel; Fernandes (2007), the use of

trinexapac has been highlighted by its efficiency in reducing

the height of plants and improving the leaf architecture of

wheat and by increasing the stem diameter, reducing lodging

and optimizing the use of solar radiation, with increased

productivity.

In wheat, medium to small cultivars, although less

responsive to trinexapac, can also have their grain yield

maximized by better leaf architecture and radiation capture,

by the increase in the number of fertile tillers and by the

greater targeting of photoassimilates to grain production, to

the detriment of stem development (ZAGONEL et al., 2002;

MATYZIAK, 2006; ZAGONEL; FERNANDES, 2007).

Thus, growth regulators such as trinexapac can be used

in soybean cultivars, in order to reduce plant lodging and,

consequently, increase productivity. However, there is a

certain lack of technical information when it comes to

Fabaceae, with some divergences between the results

obtained. As it is a recommended growth regulator for

grasses, there is no precision on such a regulator for other

crops. Therefore, it is necessary to intensify research on this

growth regulator, especially in soybean crops.

5. CONCLUSION

The application of growth regulator, regardless of time

and dose, optimized the productive components of the

soybean crop, cultivar BS 2606 IPRO, when compared to the

absence of the growth regulator.

6. ACKNOWLEDGMENTS

This study was financed in part by the Coordenação de

Aperfeiçoamento de Pessoal de Nível Superior - Brasil

(CAPES) - Finance Code 001.

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