Biomass accumulation and nutrient uptake of pulses at different growth stages in the parkland region of Saskatchewan
Field experiments was conducted with pea (cv. Carnival and Swing), lentil (cv. Laird and CDC Milstone) and bean (cv. CDC Camino) in 1998 and 1999 at Melfort, Saskatchewan, Canada, to determine biomass and nutrient accumulation in pulses at different growth stage and their relationship to seed yield. Pulse crops followed a similar pattern in dry matter and nutrient accumulation, which increased at early growth stages, reached maximum and then decreased at late growth stages. Pulse crops usually reached their maximum biomass at medium pod forming to early seed filling stages (75-82 days after emergence). Maximum biomass accumulation rate was 175-215 kg ha-1d-1 for pea, 109-140 kg ha-1d-1 for lentil and 53 kg ha-1d-1 for bean. Maximum uptake of nutrients usually occurred at flowering to seed filling stages (59-85 days after emergence). Maximum accumulation rate of N, P, K and S, respectively, was 4.6-4.9, 0.4-0.5, 5.0-5.3 and 0.3 kg ha-1d-1 for pea, 2.4-3.8, 0.2-0.3, 2.0-3.4 and 0.2 kg ha-1d-1 for lentil and 1.1, 0.1, 1.5 and 0.1 kg ha-1d-1 for bean. Both seed yield and nutrient uptake in seed were lower in 1999 than in 1998, due to differences in weather conditions in the growing seasons in the two years. In summary, maximum nutrient accumulation rate occurred earlier than maximum biomass accumulation rate, and maximum nutrient uptake was earlier than maximum biomass. This indicates that in order to get high seed yields, there should be sufficient supply of nutrients to plants to ensure higher nutrient uptake rate at side shooting to bud forming stage, and then a greater biomass accumulation rate at early to late bud forming stage. This further suggests that adequate supply of nutrients from soil/fertilizers at early growth stages is of great importance for high-yield crop production systems.
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