Abstract
DOI: 10.15414/afz.2014.17.04.115–121 Received 30. June 2014 ǀ Accepted 1. October 2014 ǀ Available online 24. November 2014 In the experiment, we focused on the occurrence of weed density and weed diversity, in maize and sugar beet growing region and the effectiveness of herbicide treatments on field experiment performed on site Santovka and Plave Vozokany in canopy of sunflower ( Helianthus annuus L.) in 1998 – 2000. Plave Vozokany site is located in the southeastern part of the district Levice in maize growing production region. The average daily air temperature in the region is a 9.6 °C, and the annual amount of rainfall represents 604 mm and 330 mm during the growing season respectivelly. Santovka, the second experimental site, is located in the northeastern part of the district of Levice in sugar beet growing region. The average daily air temperature in the region is 9.2 °C and the annual amount of rainfall represents 637 mm and the annual amount of rainfall during the growing season is a 354 mm. Actual weed infestation was carried out by the numerous method with a five replication on the control treatments (without herbicide application), as well as on the areas treated with herbicides. The occurence of weeds in sunflower was assessed for 3 times per growing season. The evaluated sites were infested on the level of high weed infestation. The total abundance of weeds without herbicidal treatments ranged from 39.62 pcs to 63.50 per m -2 . Herbicides application effectively decreased the weed infestation in range from 3.13 pcs to 14.81 pcs per m -2 . The most dominant weed species in the canopy of sunflower was group of one year late spring weeds as fallows: Chenopodium album L., Echinochloa crus - galli (L.) P. BEAUV, Persicaria lapathifolia RAF. S. F. GRAY, Persicaria maculata RAF. S. F. GRAY, Amaranthus retroflexus L. and Atriplex sp.. Another most abundant weeds species designated as very dangerous species were Tripleurospermum perforatum (L.) SCHULTZ-BIP., Avena fatua L., Elytrigia repens (L.) DESV, Cirsium arvense (L.) SCOP. and Convolvulus arvensis L.. In pursuing the weed species diversity in Plave Vozokany site, we found medium dependence on air temperature during the year (r= 0.363427), and indirect dependence with rainfall pattern (r= -0.08196). The average weed density was in the indirect dependence on the air temperature (r= -0.98317), but strongly dependent on rainfall (r= 0.889926). Higher weed infestation was noted in the growing years when early spring to early summer was warm and humid. Lower weed infestation was noted when this period was dry. Differences in overall weed infestation, as well as the effectiveness of the used herbicides between experimental sites were at the same level of importance. Keywords : sunflower, herbicides control, weed density, weed diversity
Highlights
All plants in the agrophytocenoses are strongly influenced by human activities and habitat factors, which includes primarily soil and weather conditions of particular year
Influence of weather conditions on yield and yield forming components of sunflower has been described precisely by Černý et al (2011, 2012 a, 2012 b), they found a significant influence of year weather conditions to specific yield forming components of sunflower
The occurrence of weeds in sunflower was assessed for 3 times per growing season in five replications, on the control plots, as well as on the areas treated with herbicides
Summary
All plants in the agrophytocenoses are strongly influenced by human activities and habitat factors, which includes primarily soil and weather conditions of particular year. Among these factors other factor is need to include, such as the relief of area, the exposure of field and structure of growing crops (Aldrich and Kremer, 1997; Stephenson, 2000). Weed competition with sunflowers during the first four weeks after crop emergence from species adapted to cool conditions, like wild mustard, kochia and wild oat, can reduce sunflower yield by 30 %. Rainfall, as well as wind can significantly effect the action of applied herbicides, e.g. some active ingredients of herbicides act poorly at low air temperatures (Pannacci et al, 2007). In addition to the air temperature the soil temperature is one of the factors that significantly influences the germination and emergence of seeds of sunflower, and of the weeds
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