Browsing by Author "Bukun, Bekir"

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Critical Period of Weed Control in Chickpea Under Non-Irrigated Conditions
(Tubitak Scientific & Technological Research Council Turkey, 2011) Tepe, Isik; Erman, Murat; Yergin, Reyyan; Bukun, Bekir
The present study was conducted during the growing seasons of 2005, 2006, and 2007 to determine the critical period of weed control (CPWC) in chickpea (cv. Aziziye 94). In order to evaluate the beginning of CPWC, weeds were allowed to compete at weekly intervals for 1 to 8 weeks after emergence (WAE) and, at the end of CPWC, plots were kept weed-free at weekly intervals for 1 to 8 WAE by periodic hand hoeing. The beginning and the end of CPWC were based on 5% acceptable yield loss (AYL) levels, which were determined by fitting logistic and Gompertz equations to relative yield data, representing increasing duration of weed-interference and weed-free period, estimated as growing degree days (GDDs). The major weed species were Centaurea depressa Bieb. and Bromus tectorum L. for the 1st year, Salsola ruthenica Iljin., Amaranthus sp. and Heliotropium europaeum L. for the 2nd year and Amaranthus spp., Salsola ruthenica Iljin., Sisymbrium septulatum DC. and Heliotropium europaeum L. for the 3rd year. Overall weed density was 190 plants m(-2) in 2005, 215 plants m(-2) in 2006, and 191 plants m(-2) in 2007. Yield losses were 26.4% in 2005, 31.5% in 2006, and 25.0% in 2007 when the crop was not weeded. It was found that at the 5% AYL level CPWC was 2.32 WAE to harvest in the 1st year, from emergence to harvest in the 2nd year, and from 0.34 WAE to harvest in the 3rd year. The present findings suggest that the determination of CPWC is crucial in chickpea production.
Critical Period of Weed Control in Winter Lentil Under Non-Irrigated Conditions in Turkey
(Academic Journals, 2008) Erman, Murat; Tepe, Isik; Bukun, Bekir; Yergin, Reyyan; Taskesen, Mehtap
This study was conducted during the growing seasons of 1998-1999 and 2003-2004 to determine the critical period of weed control (CPWC) in winter-lentil (cv. Sazak-91). The experiments were laid out in a randomised block design with four replications. The beginning and end of CPWC were based on 5% acceptable yield loss levels which were determined by fitting logistic and Gompertz equations to relative yield data, representing increasing duration of weed-interference and weed-free period, estimated as growing degree days (GDD). The results indicated that CPWC for seed yield was between 237 and 846 GDD in the first year and between 123 and 414 GDD in the second year, while CPWC for biomass was between 216 and 820 GDD in the first year and between 212 and 374 GDD in the second year. Thus weeds should be controlled from the first week after the onset of regrowing stage of the crop in spring up to 7th week for winter-lentil to avoid losses above 5%.