The combined allelopathic effect of wheat plant residues with doses of mineral fertilizer nitrogen (N) on yield of Sunflower (Helianthus annus L.) crops

This study was conducted on a farm associated with the Agricultural Extension Directorate of Residues Governorate during the 2023 agricultural season. The study aimed to determine the differential effect of wheat plant residues alone and with different fertilizer treatments on selected argemone characteristics of Sunflower (Agrico cultivars). The research included the evaluation of four different fertilizer treatments: no fertilization, nitrogen fertilizer at a rate of 80 kg/ha, nitrogen fertilizer at a rate of 120 kg/ha, wheat residues at a rate of 1400 g/m2m2, and wheat residues at a rate of 1400 g/m2 m2 combined with nitrogen fertilizer at 120 kg/ha).The experiment used a split-plot design, with three replicates for each treatment. The following parameters were examined: Plant height (cm), Flower disc diameter (cm), Average dry weight of the disc (g), Average seed weight per disc (g), Average number of seeds per disc (seed), Average weight of 100 seeds (g), Biological yield (kg/ha), Yield from Seeds (kg/ha) and Harvest factor (%).The results demonstrated a significant superiority of the mineral fertilization treatment (120 kg/ha) alone or with wheat residues at 1400 g/m2 concentration in most of the studied indicators over the other treatments. This was evident by the increase in the flower disk (13.21), the dry weight of the flower disk (78.06 grams), and the weight of seeds in the plant (41.45 grams). Additionally, the weight of 100 seeds was (4.947 grams), the biological yield was (27,541 kg/ha), and the seed yield was (3316 kg/ha). Regarding the plant height characteristic, the organic fertilization treatment of 120 kg/ha alone or with wheat residues at 1400 g/m2 concentrations showed superiority. This was followed by treating wheat residues at 1400 g/m2 (173.3,168.3) cm, respectively. Furthermore, the harvest index was significantly higher in the 120 kg/fertilization treatment, either alone or with wheat residue at a rate of 1400 g/m2.