Biomass growth and dry matter accumulation in barley

Biomass growth represents the net effect of photosynthesis, after losses from respiration and leaf fall. It can be assessed by measuring changes in above-ground dry matter over time.

• Growth is slow before the canopy closes
• Greatest growth occurs after the canopy closes (after early stem extension)
• Crop dry weight gain slows midway through grain filling (after considerable canopy senescence)
• Growth is maximised in bright, cool weather

Benchmark: Growth before canopy closure = 2.7 t/ha by 21 April

Varietal influence: Medium

Other influences: N supply, sowing date, plant population, temperature

Between sowing and canopy closure (about five days after GS31), around 18% of total dry matter is produced. Growth is slow during this period, which can extend up to 200 days, as the canopy is incomplete.

Benchmark: Growth after canopy closure (GAI >3) = 0.2 t/ha/day dry matter (an extra 11 t/ha by 20 June)

Varietal influence: Medium

Other influences: N supply, light, temperature, water

A GAI of over 3 is maintained for eight weeks. During this period (early stem extension to late grain fill), the crop generates about 70% of its total dry matter. The length of this phase is largely governed by temperature.

During this phase, the crop intercepts more than 70% of available light for photosynthesis. Light availability affects the rate of dry matter accumulation. Cloud cover can reduce light energy by 75%.

The canopy begins to senesce at GS59 but dry matter gain hardly decreases until midway through grain filling.

Varietal influence: Medium

Other influences: N supply, plant population

Dry matter accumulates in the ear until GS87, when maximum crop dry weight occurs. During this period, stems and leaves lose weight through respiration and translocation of carbohydrate reserves and N into the developing grain. Stems do not lose soluble reserves until after GS71, when final internodes stop extending. After GS87, as leaf tissue is shed before harvest, the crop dry weight falls.

Between GS31 and ear emergence, the crop accumulates biomass at 0.2 t/ha/day.

Final total biomass in spring barley (12.5 t/ha at GS87) is about 80% of winter barley.

Discover how wheat and barley capture and convert natural resources (solar energy, carbon dioxide and water) into edible (e.g. grain) and other forms of biomass/energy.