Nitrogen/Ammonium Concentration Response of Vegetable and Flower Crops

Nitrogen (N) is the element with the greatest influence on the growth of vegetables and ornamentals, however, form of delivery, either as nitrate (NO3 - ) or ammonium (NH4 + ) has different effects on plant development. The NO3 - is the main form of N that plants absorb, but when it is the only source of N that has slight effects on root growth, no effects over enzymatic activities, and stimulates the absorption and translocation of cations within the plant. The NH4 + is the easiest way of assimilation but is highly toxic when the only source or with respect to the concentration of NO3 - is too high. To avoid toxicity, the NH4 + must not exceed 20% of the total N amount in the formulation, however, it is important to consider the species, variety and environmental conditions. The N as supplied also affects the resistance or susceptibility of plants to diseases, but depends on the species and the type of pathogen.