The Study on Calendula officinalis L. In Mediterranean Climatic Conditions: Impact of Different Nitrogen and Phosphorus Fertilization Levels on Morphological, Yield and Physiological Characteristics

Pot marigold, Calendula officinalis L., a plant widely utilized in cosmetics, medicine, and pharmacy due to its rich bioactive compounds, was the subject of this study. The research aimed to investigate the effects of varying nitrogen (0, 50, 100, and 150 kg ha-1 N) and phosphorus (0, 50, and 100 kg ha-1 P2O5) fertilizer doses on the morphological, physiological, and yield-related characteristics of C. officinalis cultivated under Mediterranean climatic conditions. Field experiments were conducted during the 2019-2020 and 2020-2021 growing seasons in & Idot;zmir Province, western T & uuml;rkiye, using a randomized complete block design with factorial arrangements and three replications. Morphological traits, seed and flower yields, and nutrient use efficiencies were assessed. The results revealed that nitrogen and phosphorus doses, year, and their interactions significantly influenced plant growth, yield performance, and nutrient use efficiency. The highest agronomic nitrogen use efficiency based on seed yield (35.7 kg/kg N ha-1) and flower yield (49.3 kg/kg N ha-1) was recorded at 0-50 kg ha-1 N in 2020. Similarly, phosphorus use efficiency peaked at 34.5 kg/kg P ha-1 under the same conditions but declined sharply in the following year due to reduced and irregular rainfall. These findings underscore the critical influence of soil moisture on nutrient uptake and utilization. Moderate fertilizer inputs (50 kg ha-1 N and 50 kg ha-1 P2O5) provided a favourable balance between yield and nutrient efficiency. Fertilization strategies for Calendula officinalis should be based on integrated evaluations of both yield performance and nutrient use efficiency to ensure sustainable cultivation under Mediterranean agroecological conditions.