N application increases pre-anthesis contribution of dry matter to grain yield in wheat grown on a duplex soil [nitrogen fertilizer]
1995
Palta, J.A. | Fillery, I.R.P. (Commonwealth Scientific and Industrial Research Organisation, Wembley (Australia). Div. of Plant Industry)
The effect of fertilizer on the growth, post-anthesis water deficits and remobilization of dry matter in spring wheat was measured on a duplex soil at East Beverley, Western Australia. Nitrogen was applied at 15, 30 and 60 kg N per ha with half being applied at seeding and the remainder at 35 days after sowing (DAS), immediately before the onset of tillering. The applied N generated differences in early growth and dry matter at anthesis, mainly through the effect of N on tiller number and tiller size. It also generated differences in the water deficit, particularly after flowering. Grain yield at 60 kg N per ha was increased by 20% relative to that of 15 kg N per ha. The increase in grain yield resulted from an increase in the number of ears and grain number per ear. The N treatment probably induced the increase in the number of fertile tillers, but reduced the grain size by 16% relative to the low N treatment. Contribution of pre-anthesis dry matter to grain yield was 193 g per sq m for the wheat receiving 60 kg N per ha, 71 g per sq m for wheat which received 30 kg N per ha and only 16 g per sq m for wheat which received 15 kg N per ha. This indicates that at high N supply, grain growth was substantially supported by pre-anthesis stored assimilates.
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