To establish the influence of different irrigation and fertilization rates on the quality indicators of the fruit of three specific genotypes of tomatoes- Maldo, Pink Rock, and Hayet- in 2022, experiments were conducted in the experimental field of Maritza Vegetable Crop Research Institute – Plovdiv in an unheated steel and glass greenhouse type Venlo. The experiment was conducted under three irrigation regimes – optimal, reduced, and increased irrigation – 100%, 75%, and 125% using water-saving irrigation technologies and three fertilization regimes – optimal, reduced, and increased fertilization – 100%, 75%, and 150%.
It was found that reducing the water content resulted in a slight increase in dry matter, total soluble solids (TSS), and vitamin C content while varying the fertilizer rate did not significantly change the studied characteristics. Tomato fruit quality was more affected by irrigation than by fertilizer levels. Titratable acidity and pH differed between cultivars but not between treatments applied. The highest dry matter, TSS, and vitamin C contents were observed in the treatments with low irrigation rates and optimal fertilization (75%W and 100%F). Strong positive correlations were found between dry matter, TSS and vitamin C, while a strong negative correlation was found between fruit firmness and dry matter, TSS and vitamin C.
The factor Genotype had the strongest effect on the tomato fruit quality parameters studied, with a weaker but proven effect of the individual factors irrigation rate and fertilization rate on dry matter, soluble solids content, and vitamin C. The highest fruit quality was found in Pink Rock, followed by Maldo. The variety with the lowest values for most of the quality indicators is Hayet.