(Full Article in english)

Journal of Plant Diseases and Protection
Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz
Sonderheft XX, 935-940 (2006), ISSN 1861-4051
© Eugen Ulmer KG, Stuttgart
Study on the early competition between sunflower and weeds in
field experiments
É. LEHOCZKY1*, P. REISINGER2, T. KŐMÍVES3, T. SZALAI4
1
Department of Herbology and Pesticide Chemistry, Georgikon Faculty of Agricultural Sciences,
Veszprém University, Deák F.u. 16., H-8360 Keszthely, Hungary, e-mail: [email protected]
2
Department of Plant Protection, Faculty of Food and Agricultural Sciences, University of WestHungary, H-9200 Mosonmagyaróvár, Vár u. 2., e-mail: [email protected]
3
Plant Protection Institute of the Hungarian Academy of Sciences, H-1022 Budapest, Herman O. u. 15.,
e-mail: [email protected]
4
Department of Land Use and Landscape Management, Institute of Environmental Management, Szent
István University, Páter K. u. 1., H-2103 Gödöllő, e-mail: [email protected]
* Corresponding author
Summary
The aim of our study was to obtain concrete data on the competition of sunflower and weeds in the early
stage of growth by measuring the biomass production of plants and to get further information on the rate
of nutrient uptake of weeds under field conditions. The correlation between the biomass of weeds and
sunflower was evaluated. The experimental results confirm that the importance of the early competition
depends on the rate of weed infestation with special regard to the competition for nutrients.
A field experiment was carried out at Baracska, Fejer county, Hungary, on a 9.2 ha area of calcareous
loamy chernozem soil in 2004. Samples were taken five weeks after the sowing of sunflower at a growing
stage of 8 paired leaves. Weed control was done end of April 2004 on the experimental field with
herbicides as follows: Racer (fluorchloridon) 2 l/ha + Guardian Max (acetochlor + DK-29 safener) 2 l/ha
+ Prometrex 500 SC (prometryne) 2.2 l/ha. For the sake of competition studies no herbicides were applied
further on sampling sites (2 x 2 m) that were identified by DGPS (Differential Global Positioning
System).
The populations of weeds growing on the sampling areas were assayed by using the Balázs-Ujvárosi
coenological method and from six randomly selected sampling areas all weed and crop plants were
harvested. Plants belonging to different taxa were separated, identified, counted, and the plants’ fresh and
dry weights were measured. For comparison, sunflower plants were harvested from neighboring
herbicide-treated sites and analyzed.
Altogether 13 weed species were found such as Amaranthus blitoides, Amaranthus retroflexus, Ambrosia
artemisiifolia, Bilderdykia convolvulus, Cannabis sativa, Chenopodium album, Chenopodium hybridum,
Datura stramonium, Echinochloa crus-galli, Hibiscus trionum, Panicum miliaceum, Polygonum persicaria
and Solanum nigrum. On average seven weed species were found per sampling site.
As a result of crop-weed competition, the shoot mass of sunflower plants was 23.5 % lower on weedy
sites than on herbicide treated sites (weed free). A negative linear correlation was found between the
biomass weight of weeds and the shoot weight of sunflower. We found that uptake of large amounts of
nutrients by weeds at the early stage of the development of sunflower is an important factor in crop-weed
competition. As a result, the shoots of weed-free sunflower contained 22 % more nitrogen, 31 % more
phosphorus and 43 % more potassium than those collected from weedy areas.
Keywords: Crop-weed competition, biomass production, nutrient uptake, sunflower, DGPS
936
LEHOCZKY, REISINGER, KŐMÍVES, SZALAI
Zusammenfassung
Untersuchungen zur frühen Konkurrenz zwischen Sonnenblume und Unkräutern unter Feldbedingungen
Untersuchungen zur Konkurrenz zwischen Sonnenblume und Unkräutern wurden 2004 auf einer
Teilfläche von 17,8 ha eines 52 ha großen Sonnenblumenfeldes in Baracska (Lks. Fejér, Ungarn) auf
kalkhaltigem Tschernosem durchgeführt. Die Probenahme erfolgte am 1. Juni, 5 Wochen nach der Saat.
Zu diesem Zeitpunkt befand sich die Sonnenblume in einem Entwicklungsstadium mit 8-9 Blättern. Auf
der Untersuchungsfläche wurde Ende April mit den Herbiziden Racer (Fluorchloridon) 2 l/ha + Guardian
Max (Azetochlor + Antidotum) 2 l/ha + Prometrex 500 SC (Prometrin) 2,2 l/ha eine Unkrautbekämpfung
durchgeführt.
Auf den mit DGPS (Differenzielles Globales Positionssystem) markierten 2 × 2 m großen Versuchsparzellen wurde keine weitere Herbizidbehandlung vorgenommen. Auf diesen Flächen konnten sich
sowohl die Kultur- als auch die Unkrautpflanzen „ungestört” entwickeln. An den Probenahmestellen
wurden mit der Balázs-Ujvárosi Methode eine Unkrauterfassung durchgeführt. Anschließend wurden
sämtliche dort vorkommende Unkrautpflanzen je nach Art gesammelt, abgezählt und schließlich die
Frisch- und die Trockenmasse der Sprosse erhoben. Von den Probenahmestellen und aus dem herbizidbehandelten Umfeld wurden je 10 Sonnenblumen entnommen, ihre Blattanzahl, Sproßlänge, Frisch- und
Trockenmasse ermittelt. Darüber hinaus wurde der Nährstoffgehalt (N, P, K) der entnommenen Sonnenblumen und der Unkräuter festgestellt.
Es wurden insgesamt 11 annuelle dikotyle Unkrautarten registriert (Amaranthus blitoides, Amaranthus
retroflexus, Ambrosia artemisiifolia, Bilderdykia convolvulus, Cannabis sativa, Chenopodium album,
Chenopodium hybridum, Datura stramonium, Hibiscus trionum, Polygonum persicaria, Solanum nigrum)
und zwei annuelle monokotyle Arten (Echinochloa crus-galli, Panicum miliaceum), alle mit dem
Wärmeanspruch der Lebensform T4. Auf den Erfassungsflächen kamen durchschnittlich sieben Unkrautarten je Parzelle vor. Es war eine starke Konkurrenz zwischen Kultur- und Unkrautpflanzen zu beobachten, in deren Folge die Sprossmasse der Sonnenblumen auf den verunkrauteten Flächen um 23,5 %
geringer war als auf den mit Herbiziden behandelten Flächen. Zwischen der Biomasse der Sonnenblumen
und der Unkräuter konnte ein negativer linearer Zusammenhang nachgewiesen werden.
Die Sonnenblumen auf den mit Herbiziden behandelten Flächen enthielten 22 % mehr Stickstoff, 31 %
mehr Phosphor und 43 % mehr Kalium als die Sonnenblumen der unbehandelten Vergleichsflächen.
Stichwörter: Konkurrenz, Sonnenblume, Biomasse, Nährstoffaufnahme, DGPS
Introduction
On cultivated areas, there is a constant competition between weeds and crops for nutrients, light and
water. As far as densely-sown cultures are concerned, the winner of this competition is usually the crop,
while in the case of loose-standing cultures, without human assistance, weeds are the winning competitors. In the early stage of their life cycles – i.e. as long as the vital factors required for their living are in
abundance – weeds and crops are able to co-exist without causing any threat to each other. Living
conditions will start to deteriorate when there is a shortage of nutrients, water and light. Today, the
critical period of competition is known exactly for most crops. This is the time of major damage,
influencing the entire vegetation period and having a great impact on yield volume and quality
(BERZSENYI 2000, LEHOCZKY et al. 2004).
In general, the critical period of competition are the first weeks or months of the vegetation period. In
the case of maize, for instance, the beginning of this period is the third or fourth week after emergence.
The critical period of competition was the subject of numerous studies in Hungary (DOBOZI-LEHOCZKY
2004, HUNYADI 1988, LEHOCZKY-BOROSNÉ NAGY 2002, LEHOCZKY 2002, VARGA et al. 2002, LEHOCZKY
et al. 2004). According to these findings, certain weed species reduce crop yield and biomass production.
The issue of competition between sunflower and weeds has not been extensively studied so far. It is
common knowledge that by spreading of roots sunflowers are able to efficiently utilize even scarcely
available sources of water and nutrients. Sunflower has a good weed-suppressing ability (LÁNG 1976).
Early competetion between sunflower and weeds
937
The purpose of our study was to determine the level of competition for nutrients between sunflower and
weeds in the early stage of growth and to contribute to the competition-related scientific knowledge base.
Materials and methods
A field experiment was performed on a calcareous chernozem soil (Tab. 1) at the Annamajor Farm of
Baracska, Hungary, in the summer of 2004. The plot was cultivated with maize in the year preceding the
experiment. Following the maize harvest, a deep ploughing was performed in autumn, and then a leveller
and a cultivator were used to prepare the plot for sunflower sowing in spring of 2004. At the same time, a
complex fertilizer (MAS) was applied at a rate of 175 kg/ha. The sowing of sunflower (Alexandra hybrid)
was performed in April at a plant density of 53,000 plants/ha. The area was given a pre-emergent
herbicide treatment with a combination of Racer 2.0 l/ha (fluorochloridon), Guardian Max 2.0 l/ha
(antidoted acetochlor) and Prometrex 500 SC 2.2 l/ha (prometryne) soon after sowing. The harvest of
sunflower took place in October and the average yield amounted to 3.6 tons/ha.
For the sake of the competition studies, no herbicides were further applied on foil-covered sampling
sites of 2 x 2 m, identified by DGPS, in order to ensure a “undisturbed” development for both crop and
weeds on these control sites.
Weed and crop samples were taken in June (5 weeks after the sowing of sunflower) at a growing stage
of 8-9 paired leaves. The populations of weeds growing in the sampling areas were assayed by using the
Balázs-Ujvárosi coenological method (UJVÁROSI 1973, REISINGER 2001). After that all weeds on such
areas were collected. Plants belonging to different taxa were separated, identified, counted, and fresh and
dry weights were determined. Ten sunflower plants were collected both from the sampling areas and from
the herbicide-treated surrounding areas. The concentrations of different macronutrients (N, P, K % in dry
matter) of the plant samples were examined.
Tab. 1: Soil properties of the project area [means (±variances)].
Tab. 1: Bodeneigenschaften der Versuchsfläche [Mittelwerte (±Varianz)].
Type
FAO
USDA
Texture
Calcaric
phaeosem
Mollisol
Loam
Organic matter
[%]
CaCO3
[%]
AL-P2O5
AL-K2O
pH
[mg kg-1]
[mg kg-1]
3.2 [0.83]
7.5 [1.8]
5.7 [1.2]
283 [54]
314 [39]
On a total area of 9.2 ha 21 sampling sites were marked (at a frequency of 0.5 ha). All weeds on six of
such sites were collected by variety, their numbers were counted and then the fresh and dry weights were
measured. The mathematical-statistical analysis of the data was done by MS Excel and ANOVA-SPSS.
Results
Weeds
Altogether 13 (two monocotyledonous and 11 dicotyledonous) weed species were found, all of them
being heat-demanding T4 weeds. Each sampling site (plot) contained an average of seven weed species
(Tab. 2). The weeds present on the sampling sites had an average density of 152 plant m-2, representing a
wide scale from 66 to 340 plant m-2. The two dominant species, Datura stramonium and Panicum
miliaceum, were present on each plot and showed a significant density and a high biomass production.
938
LEHOCZKY, REISINGER, KŐMÍVES, SZALAI
Tab. 2: Weed species present on the sampling sites, listed by occurrence and density (plant m-2).
Tab. 2: Unkrautarten auf den Probennahmeflächen, aufgelistet nach Vorkommen und Dichte (Pflanzenanzahl m-2).
Range
1.
1.
1.
2.
2.
3.
3.
4.
4.
4.
5.
5.
5.
Minimum Maximum Average
Density (plants m-2)
16
155
70
Datura stramonium
3
154
53
Panicum miliaceum
2
55
14
Cannabis sativa
3
16
5
Chenopodium hybridum
2
7
3
Amaranthus retroflexus
1
2
0.4
Amaranthus blitoides
10
27
6
Solanum nigrum
4
24
4.5
Chenopodium album
0.5
1
0.3
Polygonum persicaria
1
3
0.5
Echinochloa crus-galli
0
1
0.04
Ambrosia artemisiifolia
0
1
0.04
Bilderdykia convolvulus
0
1
0.1
Hibiscus trionum
Weed species
Biomass production
The total average biomass weight of the weeds present on the sampling sites amounted to 16.16 g m-2,
which was similar to the average dry biomass weight of 16.69 g m-2 obtained for the sunflower plants coexisting with weeds (Tab. 3 and 4). The dry biomass weight of sunflower plants living on the weedy
sampling sites ranged between 11.24 and 19.24 g m-2. Within the total vegetable (weeds+sunflower
plants) biomass production per unit area, the share of sunflower accounted for 26-81 %.
Sunflower showed a significantly (by 23.8 %) lower biomass production on weedy plots than on the
herbicide-treated areas. The average dry biomass weight of sunflower on herbicide-treated areas was
21.84 g m-2, which is one-third higher (31 %) than the same value measured on the untreated areas.
A negative linear correlation was found between the biomass weight of weeds and the shoot weight of
sunflower (Fig. 1). According to the relationship analysis, 1 g of dry weed biomass caused a reduction of
0.37 g in the shoot weight of sunflower per m2.
Tab. 3: Average fresh and dry weight of weeds present on the sampling sites.
Tab. 3: Frisch- und Trockengewicht der Unkräutern auf den Probenahmeflächen.
Fresh shoot weight Dry matter weight
(g m-2)
1 Panicum miliaceum
51.77
7.62
2 Datura stramonium
25.40
3.52
3 Cannabis sativa
14.36
3.47
4 Chenopodium hybridum
3.22
0.43
5 Amaranthus retroflexus
1.49
0.50
6 Amaranthus blitoides
0.27
0.05
7 Solanum nigrum
1.26
0.19
8 Chenopodium album
2.93
0.43
9 Polygonum persicaria
0.50
0.08
10 Echinochloa crus-galli
0.21
0.04
11 Ambrosia artemisiifolia
0.02
0.01
12 Bilderdykia convolvulus
0.03
0.01
13 Hibiscus trionum
0.04
0.01
Total
101.50
16.16
Weed species
Early competetion between sunflower and weeds
939
2
sunflower dry biomass g/m 2
25
20
15
10
y = -0.3679x + 22.623
2
r = 0.8974
5
0
0
5
10
15
20
25
30
35
2
weed dry biomass g/m
Fig. 1: Relationship between the dry biomass weights of sunflower and weed plants.
Abb. 1: Beziehung zwischen den Trockenmassen von Sonnenblume und Unkräutern.
Nutrient uptake
The shoot weight of sunflower was 31 % higher on the herbicide-treated areas than on the untreated plots.
As to nutrient uptake, the shoots of weed-free sunflower contained 22 % more nitrogen, 31 % more
phosphorus and 43 % more potassium than those collected from the weedy areas (Tab. 4).
Tab. 4: Biomass production and nutrient uptake (N, P, K) of sunflower on weed-free plots, sunflower on
weedy plots and weeds.
Tab. 4: Biomasse und Nährstoffgehalt (N, P, K) der Sonnenblumen auf den mit Herbiziden behandelten
Flächen bzw. auf den verunkrauteten Flächen und der Unkräuter.
Treatment
Sunflower on weed free plots
Sunflower on weedy plots
Weeds
Dry biomass weight
21.84
16.69
16.16
N content
(g m-2)
0.537
0.441
0.475
P content
K content
0.068
0.052
0.044
0.954
0.668
0.644
As to the nutrients taken up altogether by weeds and sunflower plants on the weedy areas, the share of
potassium was similar to that of biomass production: 49 % for sunflower and 51 % for weeds. However,
weeds contained 52 % and 46 % of the total uptake of nitrogen and phosphorus, respectively. The level of
nutrient uptake per unit area was almost the same for weeds as for the sunflower plants co-existing with
weeds. As a result of competition, the percentage of potassium uptake in sunflower plants was higher than
that of biomass production: it decreased by 30 %.
Conclusions
The experimental plot was dominated by weed species such as Datura stramonium, Panicum miliaceum
and Cannabis sativa. The weeds showed almost the same weight per unit area (g m-2) as the sunflower
plants.
940
LEHOCZKY, REISINGER, KŐMÍVES, SZALAI
In the case of heavy weed infestation, a competition period of only five weeks may cause a significant
drop in sunflower biomass production. According to the study results, the dry biomass weight of
sunflower shoots was 31 % higher on the herbicide-treated plots than on the weedy areas. Based on a
regression analysis, a negative linear relationship was found between the biomass weight of weeds and
the biomass production of sunflower: 1 kg of dry weed caused a reduction of 370 g in the shoot weight of
sunflower.
As to nutrients, the uptake of nitrogen showed the smallest difference between the weed-free and
weedy sunflower plants: the former contained 22 % more nitrogen than the latter. There was a strong
competition for nitrogen between weeds and sunflower plants: weeds contained 52 % of the nitrogen
uptake that was more than their dry matter share (49 %). Sunflower needs a lot of potassium and,
therefore, the potassium uptake of weed-free sunflower was 43 % higher than that of weedy sunflower.
References
BERZSENYI, Z.: Gyomszabályozási stratégiák a fenntartható növénytermesztésben. Magyar Gyomkutatás
és Technológia 1, 3-21, 2000.
HUNYADI, K.: Szántóföldi gyomnövények és biológiájuk. Mezőgazdasági Kiadó.Budapest, 358-380,
1988.
LÁNG, G.: Szántóföldi növénytermesztés. Mezőgazdasági Kiadó Budapest, 240-247, 1976.
LEHOCZKY, É.: Az Echinochloa crus-galli (L.) P.B. és a kukorica korai kompeticiójának hatása.. II. A
növények tápanyag felvétele. Magyar Gyomkutatás és Technológia 3, 21-30, 2002.
LEHOCZKY, É., A. BOROSNÉ NAGY: Az Echinochloa crus-galli (L.) P.B. és a kukorica korai
kompetíciójának hatása. I. A növények növekedése. Magyar Gyomkutatás és Technológia 3, 13-20,
2002.
LEHOCZKY, É., P. REISINGER, T. KŐMÍVES: Loss of nutrients caused by excessive weediness at the early
stage of maize vegetation period. Communications in Soil Science and Plant Analysis 36, 415-422,
2004.
DOBOZI, M., É. LEHOCZKY: Competition for nutrients between weeds and potato. Zeitschrift für
Pflanzenkrankheiten und Pflanzenschutz, Sonderheft 19, 353-359, 2004.
LEHOCZKY, É., P. REISINGER, S. NAGY, T. KŐMÍVES: Early competition between maize and weeds in the
field. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, Sonderheft 19, 319-324, 2004.
UJVÁROSI, M: Gyomnövények, gyomirtás. Mezőgazdasági Kiadó Budapest. 1973 (in Hungarian).
REISINGER, P: Weed survey on farmlands in Hungary (1947-2000). Magyar Gyomkutatás és Technológia
2, 3-13, 2001.
VARGA, P., I. BÉRES, P. REISINGER: Gyomnövények hatása a kukorica termés-eredményére szántóföldi
kísérletekben. Magyar Gyomkutatás és Technológia 1, 45-52. 2000.