Ayçiçeğinde Yabancı Ot Kontrolünde Kritik Periyot ve Uygulamaların Yabancı Ot Türleri ve Çeşitliliğine Etkileri

Abstract

This study was carried out under field conditions in Adana, Turkey in 2018 and 2019 to determine the critical period for weed control in sunflower depending on the daily growth temperature (GDD) and weed species. A log-logistic model with four parameters was used to determine the relationship between relative crop yield and both increased weed intervention time and length of weed-free periods. In addition, dominant weeds and weed densities were determined in the experimental area. Data obtained from different periods of weed intervention were compared with data obtained from seasonal weed-free plots. During the sunflower growing season, 37.4% – 41.04% yield loss was determined in sunflower due to weed competition. For 5% acceptable yield loss in the first year, the critical period in weed control was determined as 243-1181 GDD; this is 24-86 days after the crop emergence (DAE) . It was found between 269 and 1409 GDD (16-72 DAE) in the second year. In sunflower, it was determined that the removal of weeds from the plot in the weed-free period started within 2-3 weeks from the emergence and continued for 10-12 weeks. These findings may help sunflower growers to plan and implement cost-effective and appropriate weed control programs.