Calcium and silicon nanofertilizers improved morphological attributes and fatty acid composition in olive; an insight to synergistic interaction between these elements
Javad Erfani‐Moghadam, Abdolkarim Zarei
Abstract
BACKGROUND: Proper plant nutrition represents a critical determinant influencing the optimal growth, development, yield, and overall quality of fruit in fruit tree cultivation. Calcium (Ca) and Silicon (Si) play pivotal roles in enhancing plant health by reinforcing structural integrity, increasing resilience to environmental stressors and pest infestations, promoting vegetative growth, and regulating the biosynthesis of beneficial plant compounds. The utilization of nano-fertilizers for targeted and controlled nutrient release represents a promising strategy to advance sustainable agricultural practices while minimizing environmental impact. METHOD: ) were foliar sprayed on olive trees grown under field conditions. Foliar applications were administered twice during the growing season: initially in mid-May following fruit set, and subsequently in July. The physical characteristics of fruits and leaves, along with their Si and Ca concentrations, were determined by analyzing 50 samples per treatment, with results expressed as mean values. The fatty acid composition of olive oil was analyzed by gas chromatography (GC). The data sets were subjected to the normal test and the analysis of variance (ANOVA) was conducted using SAS software (version 9.4) and mean comparison was conducted using the Least Significant Difference (LSD) test at α = 0.05 significance level. Principal component analysis (PCA) and pairwise correlation analysis of traits were performed using SPSS Statistics software (version 23). RESULTS: nano-Si resulted in the maximum ratio of oleic acid to linoleic acid (10.19), unsaturated fatty acids to saturated fatty acids (6.44), and MUFAs to PUFAs (9.38). The combined foliar spraying of nano-Si and nano-Ca significantly enhanced their accumulation in both leaves and fruits of olive trees, with the highest tissue concentrations observed at the maximum application rates (800 mg L⁻¹ nano-Ca + 60 mg L⁻¹ nano-Si). Strong positive correlations was observed between oleic acid content and Ca concentrations in both fruit (r = 0.94; p ≤ 0.01) and leaf (r = 0.96; p ≤ 0.01). Additionally, MUFAs content exhibited significant association with Si levels in olive fruits and leaves (r = 0.67; p ≤ 0.05), as well as with Ca content in fruits (r = 0.92; p ≤ 0.01) and leaves (r = 0.95; p ≤ 0.01). CONCLUSION: The findings of this study emphasized the advantage of foliar spraying with Si and Ca nanoparticles on olive tree. Moreover, this study highlight the synergistic effects between silicon and calcium, as the simultaneous application of these two elements had more beneficial impacts on the olive fruit than their individual utilization.