Epsilon Archive for Student Projects

Abstract

Nutrient management is an important for improving productivity and fruit quality in horticultural crops, as the form and availability of essential nutrients can influence plant growth, yield formation and the accumulation of quality related compounds. Nitrogen plays an important role in balancing plant growth, yield and fruit quality in tomato. The balance between nitrate (NO₃⁻) and ammonium (NH₄⁺) can influence vegetative development, reproductive performance and fruit quality. This study evaluated the effects of different NO₃⁻: NH₄⁺ ratios on the growth, chlorophyll content, yield and fruit quality of Sweet SturdyTM Jo F1 tomato grown under greenhouse conditions. The experiment was conducted using a completely randomized design with three nitrogen treatments and seven biological replicates per treatment. Plants were grown in a pumice based growing medium and supplied with modified Hoagland nutrient solutions containing 100% NO₃⁻:0% NH₄⁺ (T1), 50% NO₃⁻:50% NH₄⁺ (T2) and 38% NO₃⁻:62% NH₄⁺ (T3), while maintaining the total nitrogen concentration at 266 mg L⁻¹. Plant growth and reproductive development were monitored during the experiment. Chlorophyll content, biomass, fruit yield and fruit quality attributes, including total soluble solids (TSS), titratable acidity (TA) and sugar to acid ratio, were evaluated. Nitrogen treatment significantly affected later leaf production, reproductive development, biomass production and fruit yield. The treatment without ammonium produced significantly more leaves during the later growth stages and showed the highest fruit yield, with total fruit weight of 358.6 ± 7.6 g per plant, compared with 270.3 ± 7.7 g per plant in 50% ammonium treatment and 219.5 ± 5.3 g per plant in high ammonium treatment. Chlorophyll content did not differ significantly among treatments. 50% ammonium treatment recorded the highest TSS (6.67 ± 0.19 °Brix) and sugar to acid ratio (23.00 ± 1.30), while the treatment without ammonium recorded the highest titratable acidity (0.48 ± 0.01). High ammonium treatment generally showed intermediate fruit quality values. Overall, the treatment without ammonium supported greater plant development, biomass production and fruit yield, while an intermediate ammonium treatment resulted in higher soluble solids and higher sugar to acid balance. Increasing the ammonium proportion to 62% did not provide additional benefits in fruit quality and was associated with reduced growth and yield under the conditions of this experiment. However, the treatments differed not only in NO₃⁻:NH₄⁺ ratio but also in nutrient solution EC and the concentrations of related ions, particularly sulfate and chloride.