The translocation of nitrate in intact plant of barley (Hordeum vulgare L. cv.) two genotypes, wild type Steptoe and a mutant Az12, was visualized by a positron-emitting tracer imaging system (PETIS) after supplying positron-emitting 13N-labelled nitrate (13NO3−) to the seedlings. 13N movement was monitored to visualize the distribution of radioactivity in the two genotypes. N sufficient seedlings causes enhanced N uptake and translocation to shoots in time course from (0, 10, 20, 30, 40 min). The N-depleted seedlings were exposed to a nutrient solution containing nitrate and nitrite, and were labeled with 15N for 38 h under (14L/10D) cycles. The two genotypes utilized 15NO3− and accumulated it as reduced 15N, predominately in the shoots. In the Az12, nitrate accumulation in shoots was 78% higher than that in the Steptoe. Accumulation of reduced 15N in the Az12 roots was nearly similar to that of the Steptoe roots, but 8% lower in the Az12 shoots than in the Steptoe shoots at the end of the experiment.
Part of the book: Root Biology