Response of Sunflower (Helianthus annuus L.) to Plant Nutrition Systems in the Soil under Foliar Spraying by Amino Fish AMI-16, Fulvic Acid and Microfertilizer

Sunflower is one of the plants that must receive nutrients, particularly nitrogen, and often responds positively to fertilizers. Optimizing fertilizer application in oil crops not only enhances grain yield but also leads to an increased percentage of seed oil. Furthermore, it improves plant resistance to environmental stresses such as drought, salinity, and frost. Additionally, this optimization contributes to enhanced biological activity in the soil, early crop production, decreased concentrations of pollutants like cadmium in seeds, reduced toxicity, and increased efficiency in water consumption. Despite the crop's considerable potential, its cultivation has been confined to relatively poor soils and has suffered from inadequate fertilizer management, marked by unbalanced nutrient consumption, thereby limiting its overall performance. Considering the comparatively low organic matter content in Iranian soils and the environmental repercussions of continuous nitrogen fertilizer use, ensuring optimal nutrition for this crop is crucial. Hence, given the significance and necessity of proper and environmentally sustainable nutrition, this study aimed to explore the impact of various fertilizer types on the yield and components of sunflower. The investigation also incorporated diverse nutritional supplements through foliar spraying to identify the most effective fertilizer in combination with a nutritional supplement.

A field study was conducted to determine the effects of different nutrition systems and foliar spraying on sunflower yield and its components. The experiment was conducted as a split-plot based on a randomized complete block design with three replicates on a research farm at “Khaje Marjan” village under the supervision of the Sophian Agricultural Jihad organization in 2019. Factors were soil fertilization (nitrogen fertilizer of urea, vermicompost, and mycorrhizae) as the main plot and foliar spraying (amino fish AMI-16, fulvic acid, and micro fertilizer) as the subplot. Soil fertilizers were used at the beginning of the growing season, and foliar sprayings were used before flowering and flowering stages. Data were subjected to ANOVA using Minitab ver. 17.0 and SAS ver. 9.2.0 statistical software. The main and interaction effects of experimental factors were analyzsed as a PROC GLM by slicing interactions in SAS software. The assumption of the variance analysis was tested by ensuring that the residuals were random, homogeneous, and with a normal distribution about a mean of zero using residual plots and the Anderson-Darling test. Means were separated using Fisher’s least significant difference (FLSD) test at a 0.01 significance threshold.

Results indicated that the highest yield and its components were obtained using mycorrhizae and vermicompost compared to nitrogen fertilizer. In addition, the highest yield and its components were obtained when micro fertilizer and amino fish AMI-16 were used as foliar spraying treatments compared to fulvic acid and control. Interaction effects showed that the highest yield and seed oil yield are related to micro fertilizer foliar spraying + vermicompost and micro fertilizer + mycorrhizae by 4292.90 and 2035.95 kg ha-1, respectively. However, there was no significant difference between these treatments and the application of amino fish AMI-16 as foliar spraying with mycorrhizae and vermicompost. Biological and organic fertilizers provide the required nutrients of crops during the growth period, and stresses are not imposed on nutrients and water deficit. Although fulvic acid is one of the effective sprays in increasing the yield and its components and increasing the performance of this industrial crop compared to control, its effect was less than micro fertilizer and amino fish AMI-16.

Therefore, it can be concluded that foliar spraying of micro fertilizer or amino fish AMI-16 with mycorrhizae and vermicompost can be provided water and nutrients required for sunflower plants in the sensitive growth stages especially seed filling periods, and resulted in increased yield and its components. The results of this study can be used in the extensive cultures of this industrial crop to achieve the highest grain and oil yield.