Effect of foliar spraying with fertilizer of nano NPK on vegetative growth and fruit quality of the local Navel Orange cultivar

This study was conducted to evaluate the effect of foliar spraying with several concentrations of fertilizer of nano-NPK on improving vegetative growth, crop characteristics and fruit quality of the variety of Navel orange under the conditions of Karbala Governorate during the agricultural season 2024. The results of the study indicated that foliar spraying with nano-NPK fertilizer significantly affected all vegetative growth characteristics. The 750 mg/L treatment recorded the highest averages in chlorophyll content, leaf area, branch length, and number of leaves per branch, which in general led to a clear improvement in the plant's physiological efficiency. Increasing the concentration to 1000 mg/L did not result in any significant improvement in the studied traits. Regarding productive traits, the treatment with a concentration of 750 mg/L also outperformed, yielding the highest average fruit weight (206.1 g), the highest number of fruits (269 fruits/tree), and the highest yield per tree (54.9 kg), compared to the other treatments. This reflects the effect of adding nano-fertilizers in increasing the efficiency of photosynthetic product transport and enhancing fruit set. Regarding fruit characteristics and quality, the treatment with a concentration of 750 mg/L achieved the highest values for fruit length and diameter, juice content, total soluble solids (TSS), and TSS/acidity ratio, along with a significant decrease in total acidity. Therefore, the use of foliar spraying with nano-NPK is an effective field management technique for improving vegetative growth, yield, and fruit quality of the local Iraqi Navel Orange cultivar.