Division of Agronomy, Indian Agricultural Research Institute, New Delhi-110012, India.
* Present Address: Indian Institute of Soil Science, Nabibagh, Berasia Road, Bhopal-462 038, India.
An experiment was conducted during 1995–1996 and 1996–1997 to study the pattern of weed flora in sunflower during kharif and spring seasons. The season-long weed infestation caused 54.6 and 25.7% reduction in seed yield during kharif and spring seasons, respectively. The dominant weeds with respect to population and dry matter accumulation during kharif were Trianthema portulacastrum (19.75; 28.35%) and Digera arvensis (27.26; 27.42%), while during spring season Heliotropium eichwaldi (38.38; 37.50%) and Melilotus indica (17.44; 18.6%) were predominant. Cyperus rotundus persisted in both the seasons and was abundant in initially weed free treatments. Removal of weeds for initial 45 days reduced weed population by 63.2 and 62.0% and weed dry weight by 76.0 and 80.5% in kharif and spring seasons, respectively. Sunflower crop required an initial weed free period of 45 days during kharifand 30–45 DAS in spring.
