The effect of nitrate on early seedling growth in Zea mays

During early seedling growth in maize, there is an initial lag before an increase in embryo nitrogen is seen, a period of rapid nitrogen increase, and finally a period of relatively minor change. Additions of NO3− to this system do not alter the nitrogen content of the seedlings during the phase of nitrogen increase. They do, however, extend this phase and this results in higher protein and alcohol-soluble nitrogen by day 6. NO3− additions have no effect on the loss of nitrogen from the endosperm. NO3− additions have a minor stimulatory effect on seed germination.The primary leaf also showed three phases of protein increase. Additions of NO3− lengthened the period of rapid protein increase, resulting in a higher level of leaf protein.The steady-state level, or inducible level, of nitrate reductase in the primary leaf is low initially, reaches a peak 7–8 days after sowing, and then declines. The results suggest that NO3− has little effect on the endogenous synthesis of nitrogenous compounds in the embryo at a time when amino acids are supplied by the endosperm.