FirstGrainsFilling

The FirstGrainsFilling phase in Lentil represents the developmental period from FirstGrainsVisiable to TerminalNode. This is the critical grain-filling period when grains accumulate dry matter and nutrients.

Overview

The GenericPhase model simulates the grain-filling process using daily Thermal Time.

  • This phase starts at FirstGrainsVisiable and ends at TerminalNode
  • The main stem reaches determinate growth, forming a terminal node
  • Grains accumulate starch and protein
  • The model uses daily thermal time, retrieved from the [Phenology].ThermalTime function
  • This is the most critical phase for biomass and yield accumulation

Grain-Filling Characteristics

During this phase:

  • Grains rapidly increase in size and mass
  • Starch accumulation is highest during this period
  • Protein content increases
  • Concurrent flowering and pod development continues at upper nodes
  • Later grains fill at same time as earlier grains
  • The duration and rate of grain filling directly affect final grain weight

Cultivar-Specific Parameters

Name Description Default Value
[Phenology].TtFlowerDevelopment Thermal time from budding to flowering (°Cd) 200

Practical Considerations

Critical factors affecting grain filling:

  1. Temperature: Optimal temperatures enhance grain filling rates
  2. Water availability: Most critical phase for water requirement; stress reduces grain weight
  3. Radiation: High photosynthetically active radiation ensures adequate carbohydrate supply
  4. Nitrogen availability: Supports protein accumulation in grains
  5. Crop maturity stage: Late-sown crops may have shorter grain-filling periods with lower yields

The model simulates this critical phase as the period when grain dry matter accumulates most rapidly. Water stress during this phase has the most severe impact on grain yield.