Effects of Different Nitrogen Sources and Sodium Bicarbonate on Growth and Nutrient Uptake in Two Garlic Genotypes: A Hydroponic Study

Soil alkalinity is a major constraint to agricultural production worldwide, as only a limited number of plant species . Nitrogen sources significantly influence the pH of the nutrient solution. This study was conducted as a factorial experiment based on a completely randomized design with three factors: sodium bicarbonate at three concentrations (0, 10, and 20 mM), nitrogen source at three levels (ammonium sulfate, ammonium nitrate and calcium nitrate at a concentration of 5 mM), and two garlic genotypes (white and purple), with three replications in a hydroponic greenhouse at the Faculty of Agriculture, Vali-e-Asr University of Rafsanjan. Also, the results showed that increasing sodium bicarbonate concentration led to a decrease in morphological parameters. Manganese and sodium concentrations increased with higher sodium bicarbonate levels, particularly under calcium nitrate and ammonium sulfate treatments. Ammonium nitrate also increased iron and copper concentrations. Additionally, ammonium sulfate and calcium nitrate improved nutrient uptake. Based on the findings, the white garlic genotype demonstrated superior performance in most measured traits compared to the purple genotype. The interaction between nitrogen form and nutrient solution pH was shown to influence nutrient uptake efficiency, stress tolerance, and overall plant performance. These findings highlight the critical role of targeted nitrogen management in alleviating the negative impacts of alkaline stress on garlic cultivation. By addressing nutrient imbalances and promoting better growth performance, appropriate nitrogen source strategies can enhance the resilience and productivity of garlic genotypes under hydroponic conditions, thereby supporting more efficient and sustainable agricultural practices.