Effects of sunflower (Helianthus annuus L.) extracts on wheat (Triticum aestivum L.) and physicochemical characteristics of soil

Pot-grown seedlings of wheat cultivars Margalla 99 and Chakwall 97 were given water mixed with extracts of sunflower leaves, stems, or roots 20 days after the seedlings had emerged. Data on growth and yield parameters, weed density, and hormone production were recorded. Physicochemical properties of soil were analysed before sowing sunflower and after harvesting wheat. Commonly observed effects of allelochemicals were (a) decreased production of indole-3-acetic acid and gibberellic acid and lower values of electrical conductivity, moisture content, weed density, and fresh and dry weight of weeds, and (b) increased production of abscisic acid and higher values of pH, Mn, Fe, Mg, Ca, K, 100-grain-weight, and fresh and dry weight of wheat plants.