Calcium Phosphate as Nanofertilizer for Curly-Leafed Parsley Production

Introduction/Objective The unique properties of nanomaterials have prompted their development for a wide range of applications, with their use as nano-fertilizers in agriculture gaining increasing attention. However, a knowledge gap remains regarding their impact on industrial crop production, particularly for aromatic and medicinal plants. This study aimed to study the effects of HAP NPs on the growth traits, herb and essential oil yields, and anatomical features in curly-leafed parsley ( Petroselinum crispum L.). Methods The fertilizer treatments applied in this field experiment included NK + 0.25gL -1 HAP NPs, NK + 0.50gL -1 HAP NPs, NK + 1.0gL -1 HAP NPs, a recommended dose of NPK, and a control (distilled water only). Results The results indicated that the foliar application of HAP NPs was generally comparable to, and in some cases exceeded, the effectiveness of traditional NPK fertilizers. HAP NPs at 0.50 g L −1 increased fresh herb yield by 103% (21.13 t ha −1 ) in the first harvest of the first season compared to the control treatment. In subsequent harvests, these increases averaged 45%. Moreover, the fresh herb yield under HAP NPs at 0.50 g L −1 was on average 26% higher than that of plants treated with NPK, except during the first harvest of the second season, where the differences were not statistically significant. In addition, HAP NPs treatments at 0.50gL -1 led to significant increases in the dry herb yield (7.20–7.81 t ha 1 ) as well as a notable enhancement in essential oil yield (13.97–15.63 L ha 1 ), compared to both the control and NPK treatments. Conversely, the growth and yield characteristics were negatively affected by high concentrations of HAP NPs (1.0 g L -1 ). However, the foliar application of HAP NPs enhanced various anatomical features of the lamina and petiole leaves compared to the NPK solution. Specifically, HAP NPs at 0.50gL -1 resulted in the highest values for gland diameter, thickness of phloem and xylem tissues, and pith diameter of the leaf petiole. Additionally, it improved the overall thickness of the lamina, phloem, and xylem tissues. Discussion The application of 0.5 g L −1 HAP NPs represents a significant advancement in the industrial cultivation of curly-leafed parsley, particularly in alkaline soils. This treatment effectively bridges the gap between conventional NPK fertilization and sustainable nano-technological approaches by maximizing fresh biomass and essential oil yields. The observed thickening of key anatomical structures, such as palisade tissue and vascular bundles, suggests superior physiological efficiency in nutrient transport and photosynthesis. Furthermore, the enhancement of secretory glands directly correlated with increased oil output, affirming the industrial potential of this protocol. These findings position HAP NPs as a primary candidate for high-value export crop production under specific soil conditions in Egypt. Conclusion Hydroxyapatite Nanoparticles (HAP NPs), as a developed form of nanomaterial, hold promise as a source of nano-phosphorus fertilizer. Our findings emphasize that HAP NPs at 0.50 g L-1 are the most effective treatment for optimizing curly-leafed parsley production and may also enhance its industrial quality.