Translocation of N to and from barley roots: its dependence on local nitrate supply in split‐root culture

摘要: The relationship between availability of external nitrate and N translocation root shoot was studied in N-limited barley (Hordeum vulgare L. cv. Golf). Nitrate-N added at a relative rate (i.e. per unit time plant biomass) (1.09 da-1, distributed the subroots ratios 50:50 or 80:20. plants were grown for 13 days under these conditions nutrition, another three with distribution reversed from 80:20 to 20:80. nitrale-N doses thus experienced by individual ranged 2 11 mg g-1 dry weight day-1 . 15N-Nitrate labellings performed after 3 12 nutrition. reversal additions. For all treatments, 60 82% absorbed label initially left root, 25 55% recovered roots had been supplied (cycled) via shoot. Labelling xylem end 24-h labelling period 36 46% indicating that substantial fraction prior labelling. It is concluded cycling roots, as whole, also during growth. allocation increased dose. An utilization non-translocated well an contributed this effect. Thus, results indicate sink strength N.