Effect of selected herbicides on yielding and malting quality of spring barley cultivars

ABSTRACT

The aim of the study was to determine the effect of herbicides on yields, yield components and malting quality of the grains of barley cultivars. Literature worldwide lacks works on the impact of herbicides on the brewing quality of barley. This work presents the results of field experiments and laboratory studies concerning the evaluation of the impact of herbicides, differing in terms of an active substance, on the yields, weed control and malting quality of selected cultivars of barley. The research was conducted in Poland. The herbicides affected the increase in grain yields of barley, due to their high effectiveness of weed control, resulting in an increase in the number of ears per area unit. Certain herbicides increased grain protein content and grain filling. As for malt extractivity, Kolbach index, Q index, diastatic power and beta-glucans content in wort, there were interactions between herbicides and cultivars. The impact of herbicides on parameters varied depending on cultivars. The herbicides, especially Chwastox Turbo 340 SL (MCPA + dicamba) and Secator 125 OD (amidosulfuron + iodosulfuron-methyl-sodium), worsened several (not many) malt quality parameters, depending on cultivars, but it did not contribute to disqualifying malting quality of grains. Therefore, all tested herbicides can be recommended for use by farmers.

KEYWORDS:

• Cultivars
• grain yield
• herbicides
• malting quality
• spring barley

Introduction

An increasing beer consumption in Poland causes increased interest in growing barley for brewing purposes. Competition among breweries on the beer market makes them take special care about good quality of their beer, which is strongly associated with a high malting quality of barley beans, which, according to numerous studies, depends on agronomic factors and cultivars. The yield of barley and other cereal grains and their quality largely depend on the use of chemical inputs: pesticides and fertilizers (Rasmussen et al. 1996; Pecio 2002; Petersen 2007; Pruszyński & Skrzypczak 2007; Glenk et al. 2012; Kieloch & Domaradzki 2012; Kieloch et al. 2014; Keller et al. 2015).

Spring barley is the species of low competitiveness against weeds, due to its short shoots. Hence, chemical weed control is an important agronomical factor in its cultivation. The reduction of weed infestation of barley crops due to the use of herbicides has a positive effect on the yields (Brown et al. 1995; Grundy et al. 1996; Russel et al., 2002; Fernandez et al. 2006; Kierzek & Urban 2006; Krawczyk 2007; Urban 2007; Bhullar et al. 2013) by reducing competition for water and nutrients. Various herbicides have different effects on the malting value of grains and malt (Błażewicz et al. 2003; Urban 2007). No effect of fungicide on the malting value was found (Kong et al. 2016). A high rotation of herbicides and malting cultivars of spring barley in the recent years requires that both these factors should be taken into account in the agronomic research of this plant for malting purposes. The literature contains a lot of information on the impact of herbicides on the yield of barley grains and the level of weed destruction. Literature worldwide lacks works on the impact of herbicides on the brewing quality of spring barley varieties. The research hypothesis assumed an increase in barley grain yields under the use of herbicides which reduced weed competition against barley. We did not expect a highly negative impact of herbicides on the brewing quality of grains with the possibility of interactions with herbicides. Brewing quality of grains may depend more on the varietal properties than on herbicides.

The aim of the study was to determine the effect of selected herbicides on yields, yield components and malting quality of the grains of several cultivars of spring barley.

Material and methods

The studies included six herbicides – (1) Aminopielik D 450 SL (active substance: 2,4-D – 417.5 g L⁻¹, dicamba – 32.5 g L⁻¹); (2) Chwastox Turbo 340 SL (MCPA – 300 g L⁻¹, dicamba – 40 g L⁻¹); (3) Granstar 75 WG (tribenuron methyl – 75%), + Trend 90 EC (adjuvant, active substance: ethoxylated isodecyl alcohol – 90%); (4) Mocarz 75 WG (dicamba – 50%, tritosulfuron methyl– 75%); (5) Mustang 306 SE (2,4-D –180 g L⁻¹, florasulam – 6.25 g L⁻¹) and (6) Sekator 125 OD (amidosulfuron – 100 g L⁻¹, iodosulfuron-methyl-sodium – 25 g L⁻¹).

The evaluation of the effectiveness of the herbicide protection of spring barley was based on field experiments carried out in the experimental station of IUNG-PIB in Osiny (51°28′N; 22°04′E), on good soils (heavy loamy sand). The study was performed in two cycles, differing in terms of cultivars and herbicide treatments.

Experiment 1 included the following herbicide treatments: (1) Aminopielik D 450 SL, (2) Chwastox Turbo 340 SL, (3) Granstar 75 WG + Trend 90 EC (adjuvant) and (4) without using herbicides, and cultivars: Basza, Blask and Granal, while experiment 2 – herbicides: (1) Mocarz 75 WG, (2) Mustang 306 SE, (3) Sekator 125 OD and (4) without using herbicides and cultivars: Conchita, Mauritia and Sebastian. The doses of herbicides were applied once in accordance with the recommendations of the Institute of Plant Protection – State Research Institute in Poznań (the term of spraying – phase BBCH 28) (Tables 1 and 2). The experiments were set up by the method of randomized blocks, with four replications, on plots sized 20 m². Aqueous solutions of the herbicides were applied using a knapsack sprayer Gloria operating under constant pressure of 0.25 MPa and liquid downflow of 250 L ha⁻¹. Evaluation of weed infestation (counting weeds by Frame Method – four measurements per plot in a frame measuring 100 × 25 cm) was performed. Efficacy of herbicides was assessed in percent, based on the analysis of weed infestation performed 20 days after herbicide application (in relation to the number of weeds in the control treatment). The grains were sown at a density of 3.2 mln ha⁻¹, between 7 and 12 April, under mineral fertilization (kg ha⁻¹): N (ammonium nitrate) – 35, P (superphosphate) – 27, K (potassium salt) – 62.

Table 1. Effect of herbicides on weed control (%) of dominant and other species in spring barley (mean of cultivars: Basza, Blask and Granal). Experiment 1.

Herbicides (application dose)	Active ingredient	Chenopodium album	Erodium cicutarium	Polygonum convolvulus	Viola arvensis	All weeds
Aminopielik D 450 SL (3 g ha^−1)	2,4-D + dicamba	100 a	100 a	100 a	100 a	94 a
Chwastox Turbo 340 SL (2 g ha^−1)	MCPA + dicamba	100 a	86 b	90 b	91 b	91 a
Granstar 75 WG (20 g ha^−1)	Tribenuron methyl	100 a	83 b	85 a	100 a	92 a
Check		12^a	10^a	7^a	9^a	67^b

Note: a, b – homogenous groups according to Duncan’s test.

^aPlant number of dominant weed – pcs./m².

^bPlant number of weeds (dominant and other).

Table 2. Effect of herbicides on weed control (%) of dominant and other species in spring barley (mean of cultivars: Conchita, Mauritia and Sebastian). Experiment 2.

Herbicides (application dose)	Active ingredient	Anthemis arvensis	Chenopodium album	Equisetum arvense	Viola arvensis	All weeds
Mocarz 75 WG (0.2 kg ha^−1)	Dicamba + tritosulfuron methyl	100 a	100 a	32 b	95 ab	82 b
Mustang 306 SE (0.5 L ha^−1)	2,4-D + florasulam	100 a	100 a	46 a	90 b	89 a
Sekator 125 OD (0.1 L ha^−1)	Amidosulfuron + iodosulfuron-methyl-sodium	100 a	100 a	34 b	100 a	83 b
Check		12^a	14^a	12^a	10^a	78^b

Note: a, b – homogenous groups according to Duncan’s test.

^aPlant number of dominant weed – pcs./m².

^bPlant number of weeds (dominant and other).

We assessed grain yields and their structure, grain malting quality (protein content, grain filling) and malt quality. Evaluation of malting suitability of grains was performed using the Molina-Cano method, applicable in the European Malting Union (Molina-Cano 1987). It is based on major malting quality parameters: grain protein content, grain filling, malt extractivity, Kolbach index, wort viscosity, diastatic power, fermentability and Q index (characterizing the quality of grains and malt). Statistical development of the results was carried out using the analysis of variance at a significance level of .05. Homogeneous groups were determined using Duncan’s test.

Results and discussion

The tested herbicides were highly efficient in weed control. The assessment of controlling dominant weeds of barley crops Chenopodium album (pigweed), Viola arvensis (field pansy), Erodium cicutarium (common crowfoot), Polygonum convolvulus (blackbuck), Equisetum arvense (field horsetail) and Anthemis arvensis (mayweed) and weeds is shown in Tables 1 and 2. The highest weed control efficiency concerned C. album, A. arvensis and V. arvensis, while the lowest – E. arvense. Among the herbicides, Aminopielik D 450 SL turned out to be the most effective at removing weeds. Other studies showed that Granstar 75 WG (Krawczyk 2007; Matysiak 2008) and Chwastox Turbo 340 SL (Kierzek & Urban 2006) had a similar positive effect on weed control.

All herbicides increased grain yields of the tested spring barley cultivars, mainly due to a large increase of barley spike number per unit area, as well as (to a lesser extent) to an excessive grain weight per spike (Tables 3 and 4). Similar results were obtained in other studies (Klimont, 2007b). The interaction of herbicides with cultivars was not significant; hence the results we provide are the average for all cultivars. A positive impact of herbicides on grain yield of spring barley cultivars resulted from limiting weed infestation, which contributed to limiting the loss of plants during the growing season and increasing their tillering rate.

Table 3. Effect of herbicides on yielding of spring barley (mean of cultivars: Basza, Blask and Granal). Experiment 1.

Herbicides^a	Grain yield (t ha^−1)	Spikes number (per m^2)	Grain weight per spike (g)
Aminopielik D 450	7.04 a	768 a	0.93 a
Chwastox Turbo 340	7.08 a	761 a	0.94 a
Granstar 75 WG	6.97 a	762 a	0.91 ab
Check	6.47 b	731 b	0.84 b

Note: a, b – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 1.

Table 4. Effect of herbicides on yielding of spring barley (mean of cultivars: Conchita, Mauritia and Sebastian). Experiment 2.

Herbicides^a	Grain yield (t ha^−1)	Spikes number (per m^2)	Grain weight per spike (g)
Mocarz 75 WG	5.84 a	738 a	0.80 ab
Mustang 306 SE	5.93 a	742 a	0.82 a
Sekator 125 OD	5.80 a	728 a	0.79 ab
Check	5.35 b	693 b	0.76 b

Note: a, b – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 2.

We noted a varied (neutral, positive or negative) impact of the tested herbicides on malt quality parameters of the studied cultivars of spring barley. Due to the insignificance of the interaction between herbicides and cultivars, as well as between both these factors and years, the results of grain protein content and grain filling are shown as the average for cultivars (Tables 5 and 6). Using herbicides caused an increase of grain protein content – significantly in the case of Granstar 75 WG and Sekator 125 OD (which negatively affects malting quality) and an increase of grain filling in the case of herbicides: Aminopielik D 450 SL, Mocarz 75 WG, Mustang 306 SE and Sekator 125 OD (positive impact on malting quality). Other works confirm that herbicides contribute to the increase of grain protein content of spring barley (Pawłowska et al. 1999; Pawłowska et al. 2000; Klimont 2007a; Urban 2007).

Table 5. Effect of herbicides on main malt quality parameters of spring barley (mean of cultivars: Basza, Blask and Granal). Experiment 1.

Herbicides^a	Grain protein content (d.m.%)	Grain filling (%)	Malt extractivity (%)	Q index
Aminopielik D 450	12.1 a	87 ab	82.6 ab	5.97 ab
Chwastox Turbo 340	11.9 ab	88 a	82.8 ab	5.82 b
Granstar 75 WG	12.2 a	86 ab	82.3 b	5.99 ab
Check	11.4 b	84 b	84.2 a	6.23 a

Note: a, b – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 1.

Table 6. Effect of herbicides on main malt quality parameters of spring barley (mean of cultivars: Conchita, Mauritia and Sebastian). Experiment 2.

Herbicides^a	Grain protein content (d.m.%)	Grain filling (%)	Malt extractivity (%)	Q index
Mocarz 75 WG	11.4 ab	90 a	83.2 a	5.71 ab
Mustang 306 SE	11.4 ab	90 a	83.4 a	5.65 ab
Sekator 125 OD	11.7 a	89 ab	83.6 a	5.46 b
Check	10.9 b	86 b	84.3 a	5.98 a

Note: a, b – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 2.

The significance of the interactions between herbicides and cultivars was recorded for malt extractivity (the most important parameter of malt quality), Kolbach index, Q index Tables 7 and 8), and for diastatic power (Table 7) and beta-glucans content in wort (Table 8). The decrease in malt extractivity compared to the control treatment was noted for herbicide Granstar 75 WG in the grains of cv. Basza and for herbicides Aminopielik D 450 SL and Chwastox Turbo 340 SL in the grains of cv. Blask (experiment 1), and for all herbicides in the grains of cv. Sebastian (experiment 2). On average for the cultivars, a significant decrease of malt extractivity was found only for herbicide Granstar 75 WG (experiment 1, Table 5).

Table 7. Interaction of herbicides and cultivars in regard to main malt quality parameters of spring barley cultivars: Basza, Blask and Granal. Experiment 1.

Cultivars	Herbicides^a	Malt extractivity (%)	Kolbach index (%)	Diastatic power (W-K)	Q index
Basza	Aminopielik D 450 SL	83.8 ab	46.3 ab	343 a	7.50 a
	Chwastox Turbo 340	84.0 ab	46.1 ab	340 a	7.25 a
	Granstar 75 WG	83.4 b	45.0 b	348 a	7.16 a
	Check	84.9 a	47.1 a	302 b	7.47 a
Blask	Aminopielik D 450 SL	83.0 a	42.5 b	277 b	5.05 ab
	Chwastox Turbo 340	83.3 a	43.0 ab	301 a	4.89 b
	Granstar 75 WG	83.1 a	43.7 ab	287 ab	5.16 ab
	Check	84.2 a	44.5 a	302 a	5.63 a
Granal	Aminopielik D 450 SL	80.7 b	42.0 a	353 a	5.40 a
	Chwastox Turbo 340	81.0 b	42.7 a	342 a	5.32 a
	Granstar 75 WG	81.3 ab	42.3 a	343 a	5.65 a
	Check	82.5 a	43.2 a	357 a	5.60 a

Note: a, b – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 1.

Table 8. Interaction of herbicides and cultivars in regard to main malt quality parameters of spring barley cultivars: Conchita, Mauritia and Sebastian. Experiment 2.

Cultivars	Herbicides^a	Malt extractivity (%)	Kolbach index (%)	Beta-glucans content in wort (d.m.%)	Q index
Conchita	Mocarz 75 WG	83.0 a	47.1 b	204 a	5.5 ab
	Mustang 306 SE	83.1 a	48.7 ab	184 b	5.4 ab
	Sekator 125 OD	83.2 a	40.4 c	206 a	5.2 b
	Check	83.6 a	49.6 a	180 a	5.9 a
Mauritia	Mocarz 75 WG	83.0 a	49.5 a	72 ab	5.6 a
	Mustang 306 SE	83.0 a	47.7 b	61 b	5.6 a
	Sekator 125 OD	82.6 a	49.2 a	80 a	5.4 a
	Check	83.7 a	48.5 ab	62 b	5.8 a
Sebastian	Mocarz 75 WG	83.7 b	47.0 ab	153 a	6.0 ab
	Mustang 306 SE	84.0 ab	47.7 a	122 ab	5.9 ab
	Sekator 125 OD	84.1 ab	45.3 b	133 ab	5.5 b
	Check	85.5 a	48.2 a	107 b	6.2 a

Note: a, b, c – homogenous groups according to Duncan’s test.

^aDose and active ingredients – see Table 2.

In the control treatment, we recorded a higher Kolbach index compared to herbicide Granstar 75 WG in cv. Basza, to herbicide Aminopielik D 450 SL in cv. Blask, to herbicide Mocarz 75 WG in cv. Conchita and to herbicide Sekator 125 OD in cvs. Conchita and Sebastian (Tables 7 and 8). No reaction in terms of Kolbach index was recorded in the case of cvs. Granal and Mauritia. Only herbicide Aminopielik D 450 SL had a negative impact on the diastatic power of cv. Blask (Table 7), whereas cv. Basza showed a lower diastatic power in the control treatment. The increase of beta-glucans content in wort, which negatively affects the malt quality, was caused by herbicides Mocarz 75 WG and Sekator 125 OD (Table 8).

Q index, characterizing malt quality parameters, depended mainly on the traits of cultivars and, to a lesser extent, on the type of herbicide. We recorded significantly lower values of this indicator under the use of herbicides in cv. Blask (Table 7). As for cvs. Conchita and Sebastian, a significant decrease of Q index was noted under the use of 125 OD (Table 8). No significant variability of Q index under the tested herbicides was recorded for cvs. Basza, Granal and Mauritia. On average for cultivars, Q index decreased under the influence of herbicide Chwastox Turbo 340 SL (experiment 1, Table 5) and Sekator 125 OD (experiment 2, Table 6). The decrease was not as significant as to endanger the malting value of barley grains. There was diversity of other malt quality parameters, such as wort viscosity and fermentability, among barley cultivars under the influence of the applied herbicides.

In other studies, the decrease of malt extractivity (Pawłowska et al. 1999, 2000), as well as of wort viscosity, and fermentability (Pawłowska et al. 1999) was recorded. In the broad studies of Urban (2007), the applied herbicides had a variable effect on malt quality parameters, depending on barley cultivar traits. Malt extractivity, wort viscosity and Q index worsened significantly under herbicides Segal 65 WG and Logran Extra 62 WG, and only slightly under Aminopielik Tercet 500 SL and Chwastox Trio 540 SL, having a similar chemical composition to the herbicides used in this study: Aminopielik D 450 SL and Chwastox Turbo 340 SL. The insignificant influence of the applied herbicides on malt quality parameters was stated in studies of Błażewicz et al. (2003). The results of our research are consistent with the results of other authors.

Notes on contributors

Kazimierz Noworolnik is a professor of agricultural sciences in the field of agronomy. He works in the Department of Cereal Crop Production, Institute of Soil Science and Plant Cultivation – State Research Institute in Puławy, Poland. He has above 200 research articles on crop and soil management. Presently he is involved in research on the cultivation technology as well as the quality of spring barley and spring cereal mixtures.

Danuta Leszczyńska is a habilitated doctor of agricultural sciences in the field of agronomy. She works as an assistant professor in the Department of Cereal Crop Production, Institute of Soil Science and Plant Cultivation – State Research Institute in Puławy, Poland. Presently she is involved in research on the cereal biology of growth and development, cultivation technology, the quality of grain as well as allelopathy in cereal mixtures.