Applications in sustainable production

Abstract

In conventional solution culture, differences in boron (B) concentration among plant parts and in distribution over time are often confounded with declining B supply. Using a B‐buffered solution system which maintained solutions at values that ranged from deficient to adequate, we examined B uptake and distribution in canola (Brassica napus L.) at 3 growth stages: 10 and 22 days after transplanting (DAT) and at early flowering (55 DAT). Boron concentrations in shoots and roots increased strongly with increasing solution B concentrations up to 1–2 μM B and then more weakly with increases in solution B above 2 μM B. At deficient to marginal external B concentrations, stems had higher B concentrations than leaf blades on Days 10 and 22 but not at adequate external B concentrations. In petioles, B concentration remained unchanged from Day 22 to 55 in most B treatments. With increasing external B concentrations, relative B content increased in leaf blades, decreased in roots, and generally remained unchanged in stems and petioles. Although the plants at low external B concentrations (≤ 0.55 μM) maintained vegetative growth they did not produce reproductive parts in contrast to the plants of adequate B. At the flowering stage, maximum B concentration was found in florets and growth of these plant parts was more sensitively depressed by low B than vegetative plant parts. At ≤ 0.41 μM external B concentration, reproductive growth was depressed compared to plants of ≥ 0.86 μM external B concentration, flowering was delayed for 6–8 days, and flowers aborted soon after bud burst.