Nitrogen is an essential macronutrient that greatly influences plant metabolism, growth
and development. In plants, nitrogen is taken up in the form of nitrate (NO₃⁻) or
ammonium (NH₄⁺), which affect plant physiology, root and shoot growth and the
transition to generative phase differently. In this study we investigated the effect of
nitrate and ammonium nitrogen forms on growth and development of hydroponically
grown geranium seedlings. Rooted cuttings were cultivated in a floating hydroponic
system with four treatments, differing in the nitrate-to-ammonium ratio in the nutrient
solution. Treatment with an equal ratio of nitrate and ammonium resulted in greatest
increase in shoot and root biomass, along with higher concentrations of chlorophyll a,
chlorophyll b and ammonium in leaves. Treatment with 80:20 ratio (NO₃⁻: NH₄⁺) also
had a positive effect on biomass production. A decrease in plant height was observed
only in treatment with 90 % of nitrate. Higher nitrate ratios (90 %, 100 %) promoted
earlier flowering compared to the 50 % nitrate treatment. These findings suggest that
a proper ratio of nitrate and ammonium can positively influence growth by increasing
shoot and root biomass, stimulating lateral branching and enhancing leaf production.
The quality of hydroponically grown geraniums can be improved through the
optimization of nitrogen form ratios in the nutrient solution.
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