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Field experiments were conducted in farmers’ rice fields in 2001 and 2002 to study …
Biology Articles » Agriculture » Plant Production » Effects of nitrogen fertilization strategies on nitrogen use efficiency in physiology, recovery, and agronomy and redistribution of dry matter accumulation and nitrogen accumulation in two typical rice cultivars in Zhejiang, China » Materials and Methods
FFP (N5) was based on the common practice of the farmers near the sites. Total N rate was 140 kg N/ha with 40% applied before sowing, 20% at three-leaf stage, 40% at early tillering in Jinzao22 and total N rate was 200 kg/ha with 50% applied before transplanting, 35% at tillering, 15% at flowering (FL) in Shanyou63.
Treatment N6 is SSNM, the timing of N application was fixed but the rate of N application was varied depending on leaf N status. N applications in Jinzao22 and Shanyou63 are described in Table 3, respectively. A chlorophyll meter (SPAD-502) was used to obtain SPAD values on ten uppermost fully expanded leaves in each plot.
Treatment N7 is RTNM, there was no basal N application. Weekly SPAD monitoring started at 10 d after transplanting (or 30 d after sown) and continued until flowering. If the SPAD reading was below 35, 45 kg N/ha was applied around the panicle initiation (PI) stage, 30 kg N/ha was applied for other growth stages in Shanyou63. If SPAD reading was below 34, 45 kg N/ha was applied from PI to booting stage and 35 kg N/ha was applied at other stages in Jinzao22.
Post-flowering dry matter redistribution (post-DMR)=DMA at flowering−DMA in stems and leaves at maturity,
Post-flowering nitrogen redistribution (post-NR)=NA at flowering−NA in stems and leaves at maturity,
where ΔTN was total aboveground plant N accumulation in the plot that received N fertilizer minus total aboveground plant N accumulation in the zero-N control, FN was the amount of N fertilizer applied, ΔGY was grain yield in the plot that received N fertilizer minus grain yield in the zero-N control.
Analyses were conducted on individual year data and then on 2001 and 2002 combined. Year was treated as the main unit with replication nested within years; the treatments were the subunits. Data were analyzed by the following analysis of variance (SPSS, version 11.5). Differences among treatment means were compared by least significant difference (LSD). For mean separations, LSD values were used at P
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