Sunflower phytochemicals adversely affect wheat yield.

Various researchers have reported the weedicidal potential of sunflower when used as incorporation, mulch or aqueous extract without noticing its effect on crop. This study was planned to investigate the harmful effects of sunflower phytochemicals on wheat varieties. Early laboratory experiments were performed on four wheat varieties, i.e. Inqlab-91, Punjab-96, Pasban-90 and Uqab-2000. The aqueous extract of three sunflower varieties tested against wheat varieties significantly decreased biomass of wheat seedlings, especially at concentrations of 40% and 50%. However, wheat variety Punjab-96 resisted the most, which was selected for further trials. This detrimental effect was also noticed in pot trials, the extent of which varied with the age of the wheat seedlings and number of sprays. Three early sprays with one week intervals showed maximum losses to the crop plant. The study suggests the use of sunflower extracts for the management of weeds that emerge 3-4 weeks after wheat seedlings. However, the study discourages the use of sunflower mulch or incorporation in wheat fields for weed management.