Nitrogen and dry matter partitioning of barley grown in a dryland environment

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Abstract
Fifty‐eight spring malting barley crops (Hordeum vulgare L. ‘Triumph') were monitored in the Rangitikei district, New Zealand (40°20'S), over three seasons beginning 1987/88 and covering a wide variation in soil moisture conditions during grain filling but small deficits before anthesis. The objectives were to: (1) document the range of variability of grain yield among locations and years; (2) determine if systematic patterns occurred in the dry matter (DM) accumulation and nitrogen (N) uptake; and (3) evaluate the effects these processes have on the partitioning of DM and N between the grain and the rest of the plant. Mean yearly grain yields (14% moisture) were 6.85, 5.12, and 5.07 t/ha, respectively. Grain number/m2 accounted for 79% of the variation in grain yield. On average, 63% of the N in the above ground crop was derived from soil reserves, and 87% of the total N uptake occurred before anthesis. Pre‐anthesis processes had a major effect on crop characteristics at maturity. For example, the level of crop N at anthesis (indicative of pre‐anthesis N uptake) was a good predictor of the extent of post‐anthesis partitioning of N to the grain (r = ‐0.75). Conversely, high post‐anthesis N uptake was generally not related to grain N concentration. Therefore, under dryland conditions, there is scope for improving yield by late applications of N without causing grain quality reductions. Management options for obtaining high yields of malting barley under non‐irrigated conditions are discussed. These include the use of crop N concentration at anthesis as an indicator of crop N status.