Table 3.
Straw remobilization ratios and contributions of remobilization of pre-silking Zn stores and post-silking shoot Zn uptake to grain Zn accumulation of summer maize as affected by N application rates in 2009 and in 2010.
| Year | Parameter | N treatment | ||
|---|---|---|---|---|
| N0 | N1 | N2 | ||
| 2009 | Post-anthesis Zn uptakea (mg plant–1) | 0.8 | 1.6 | 2.3 |
| Percentage of pre-anthesis Zn accumulation (%) | 68.6 | 66.3 | 55.3 | |
| Percentage of post-anthesis Zn accumulation (%) | 31.4 | 33.7 | 44.7 | |
| Zn remobilization to the grainb (mg plant–1) | 0.52 | 0.62 | 0.08 | |
| Zn remobilization efficiency (%) | 29.7 | 19.5 | 2.7 | |
| Share of grain Zn provided by remobilization (%) | 39.4 | 27.8 | 3.3 | |
| Share of post-anthesis shoot Zn uptake (%) | 60.6 | 72.2 | 96.7 | |
| 2010 | Post-anthesis Zn uptakea (mg plant–1) | 1.0 | 1.8 | 2.3 |
| Percentage of pre-anthesis Zn accumulation (%) | 65.7 | 66.0 | 57.8 | |
| Percentage of post-anthesis Zn accumulation (%) | 34.3 | 34.0 | 42.2 | |
| Zn remobilization to the grainb (mg plant–1) | 0.33 | 0.46 | 0.03 | |
| Zn remobilization efficiency (%) | 17.9 | 13.3 | 0.9 | |
| Share of grain Zn provided by remobilization (%) | 25.5 | 20.5 | 1.2 | |
| Share of post-anthesis shoot Zn uptake (%) | 74.5 | 79.5 | 98.8 | |
a Assume: ∼100% of post-silking Zn uptake from soil absorbed by roots.
b Assume: ∼100% of Zn remobilized from the straw is translocated to grains.