Biomass accumulation and nutrient uptake of cereals at different growth stages in the parkland region of Saskatchewan
Field experiments were conducted with spring wheat (cv. AC Barrie - CWRS and cv. AC Taber - CPS), barley (cv. AC Oxbow - malt and cv. AC Lacombe - feed) and oats (cv. CDC Boyer or CDC Pacer) in 1998 and 1999 at Melfort, Saskatchewan, Canada, to determine biomass accumulation and nutrient uptake in cereal crops at different growth stages, and their relationship. All cereal crops followed a similar pattern of biomass and nutrient accumulation, which increased at early growth stages, reached at maximum and then decreased at late growth stages. Cereal crops usually reached their maximum biomass at late milk to full ripening stages (72-90 days after emergence), although some cultivars had a several days difference between the two years. Maximum biomass accumulation rate was 164-204 kg ha-1d-1 for wheat, 211-308 kg ha-1d-1 for barley and 185-217g ha-1d-1 for oats. Maximum uptake of nutrients usually occurred at beginning of flower to late milk (63-82 days after emergence) in both years. Maximum accumulation rate of N, P, K and S was 2.0-4.7, 0.3-0.4, 2.4-5.1 and 0.3-0.5 kg ha-1d-1 for wheat, 2.4-5.2, 0.3-0.5, 3.1-7.6 and 0.4-0.8 kg ha-1d-1 for barley, and 2.7-3.6, 0.3, 4.2-4.7 and 0.4-0.5 kg ha-1d-1 for oats, respectively. Both seed yield and nutrient uptake were lower in 1999 than in 1998, due to differences in weather conditions in the growing season in the two years. In summary, maximum nutrient accumulation rate occurred earlier than maximum biomass accumulation rate, and maximum nutrient uptake occurred earlier than maximum biomass. This indicates that in order to get high seed yields, there should be sufficient supply of nutrients to ensure higher nutrient uptake rate at tillering to stem elongation growth stage first, then a higher biomass accumulation rate at early to late boot growth stage, a greater nutrient uptake at beginning of flower to late milk growth stage, and a greater biomass at late milk to full ripening growth stage. This also suggests that sufficient supply of nutrients from soil/fertilizers at early growth stages is of great importance for high-yield crop production systems.
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