Macronutrient deficiencies in tomato plants: impacts on symptomatology, growth, physiology, fruit yield, and quality

Abstract

In tomato production systems, nutrient limitations are a frequent abiotic challenge affecting plant development, yield, and marketable quality. This study evaluated the individual effects of macronutrient deficiencies-nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)-on visual symptoms, vegetative development, physiological parameters, and fruit-related outcomes in tomato (Solanum lycopersicum L. cv. ‘Kardelen F1’) grown in a soilless greenhouse environment. A randomized experimental design with three replicates per treatment was applied. Visual deficiency symptoms were distinctive and element-specific, accompanied by marked alterations in leaf morphology and associated physiological functions. Nitrogen deficiency resulted in the most dramatic reductions in plant height (- 52.67%), stem diameter (-37.73%), and leaf dry weight (-93.31%). Chlorophyll-a and total chlorophyll contents decreased by over 60% under N deficiency, whereas P and K deficiencies significantly increased these pigment levels by approximately 50–60% compared to the control. Nitrogen limitation caused the most substantial yield loss (-90.16%), followed by P (-61.39%) and K (-52.16%) shortages. Fruit weight declined by 59.6% with N deficiency, whereas Ca and S deficiencies had little impact on this trait. Potassium deficiency significantly decreased lycopene content (-51.11%), total soluble solids (-24.28%), and titratable acidity (- 43.47%), along with increasing pH and contributing to a more yellowish skin color. The greatest reduction in fruit firmness was observed under Ca deficiency (-16.0%), while the lowest vitamin C content occurred under N deficiency (-36.77%). Moreover, total phenolic and flavonoid concentrations rose significantly under N and P deficiencies, indicating a possible stress-triggered antioxidant response. These findings highlight the distinct functions of individual macronutrients and emphasize the necessity of balanced nutrition to support optimal performance and quality in substrate-grown tomato crops.