Browsing by Author "Tepe, Isik"
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Article Changes of Weed Flora in Cereal Fields Over the Last 31 Years in Van, Turkey(Pakistan Botanical Soc, 2020) Ozkan, Reyyan Yergin; Tepe, IsikAgricultural activities carried out over time, and accordingly the developments in pest control methods, and climatic changes caused by the global warming affect the composition and density of weeds in agricultural areas. In order to determine and reveal the causes of this change, a survey was conducted on cereal fields in Van in 2017 and compared with the results of a 31 years old survey. A total of 71 weed species belonging to 23 plant families were identified in 2017, while 84 weed species belonging to 24 plant families were identified in 1986. Looking at the weed density in unit area, it was found that the weed averages were 41.8 in a square meter in 2017 and 82.8 in 1986. In both surveys, the number of weed species was almost equal to each other and the coefficient of Similarity Index (SI) for 2 surveys was calculated as 0.58 in terms of weeds. While the roughfruit corn bedstraw (Galium tricornutum Dandy.), tuberous cranesbill (Geranium tuberosum L.) and rye (Secale cereale L.) were detected as the most intensive species in 1986, the narrowleaf knotweed (Polygonum bellardii All.), goatgrass (Aegilops spp.) and summer pheasant's eye (Adonis aestivalis L.) were identified as the densest species in the recent study. When the weed distribution was assessed based on their abundances, the field bindweed (Convolvulus arvensis L.) with 21.3% frequency of occurrence and yellowweed (Boreava orientalisJaub. & Spach) with 19.5% frequency of occurrence were detected as the most common weeds in 2017. The field bindweed (Convolvulus arvensis L.) was the most common weed type in both studies, while the yellowweed was found to be common only in 2017. When both studies were compared, it was seen that the total weed density had decreased at a significant level during the last 31 years, although there had been significant increase in the density of several weeds, such as the yellowweed (Boreava orientalis Jaub. & Spach). It is considered that this decrease was due to the increase in cultivation and pest control techniques.Article Control of Smoothseed Alfalfa Dodder (Cuscuta Approximata) in Alfalfa (Medicago Sativa)(Friends Science Publ, 2017) Tepe, Isik; Celebi, Seyda Zorer; Kaya, Ilhan; Ozkan, Reyyan YerginThis study aimed to determine the most appropriate control methods for smoothseed alfalfa dodder (Cuscuta approximata Bab.), infesting alfalfa (Medicago sativa L.) in Van, Turkey. The effects of imazethaphyr and imazamox herbicides and their application times, including three cutting heights of alfalfa, on controlling dodder were investigated. The study had a split-plot design with four replications, and the trial was conducted under field conditions from 2010 to 2013. The results indicated that pre-emergence applications of imazethaphyr, pre- and post-emergence applications of imazamox, suppressed dodder during the first year after application; however, the effect decreased in the following years. In 2013, a substantial decrease in the hay yield and raw protein ratio of alfalfa was found. In addition, the control of dodder was not significantly affected by different cutting heights. (C) 2017 Friends Science PublishersArticle 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, BekirThe 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.Article 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, MehtapThis 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%.Article Effects of Sowing Methods and Rates on Weeds, Grain Yield and Some Yield Components of Wheat(Ankara Univ, Fac Agr, 2011) Kaydan, Digdem; Tepe, Isik; Yagmur, Mehmet; Yergin, ReyyanThis research was conducted to determine the effects of different sowing rates (450, 550 and 650 seed m(-2)) and sowing methods (sowing to the rows, broadcasting to seeding depth and contrary rows with 90 degrees) on weeds, grain yield and some yield components of wheat local "Tir" variety (Triticum aestivum L. ssp vulgare Vill. v. leucospermum Korn) under dryland condition of Van in 2006-07 and 2008-09 winter growing seasons. It was found that contrary rows with 90 degrees unaffected to reduce weeds density but it was highly effective sowing methods to decrease weeds biomass. However, higher seeding rates, in the current study, reduced insignificantly weeds density, but it reduced weed biomass. In the current study, sowing methods and seeding rates significantly affected grain yields and yields components. The highest grain yield was obtained 650 seed m(-2) and sowing to contrary rows with 90 degrees.Article Emergence Characteristics and Germination Physiology of Smoothseed Alfalfa Dodder (Cuscuta Approximata Bab.)(Parlar Scientific Publications (p S P), 2018) Yergin-Ozkan, Reyyan; Tepe, IsikThis study was aimed to determine the germination physiology and some emergence characteristics of smoothseed alfalfa dodder (Cuscuta approximata Bab.). The study was carried out between 2010 and 2013. The viability of the dodder was detected 98%. The seeds can be germinated at 30 degrees C as the highest and 10 degrees C as the lowest temperatures in this study. The germination ratio of smoothseed alfalfa dodder seeds increased in parallel with longer holding periods in cold at 2 +/- 1 degrees C by using stratification method. The highest germination rate was found as 50.3% for the seeds, which were left in cold throughout 133 days. The highest germination ratio was obtained from the level of 150 ppm gibberellic acid application dose in dormancy breaking study. Moreover, it was determined that the best emergence was obtained in 0.5 cm soil depth. The seeds on the soil surface died due to inadequate moisture and the seeds on the so depth (4-6 cm) did not emergence.