Growth Cycle of Barley

After germination the first leaf emerges soon after the crop initially emerges. The crop continues to produce leaves at a continuous thermal rate. This thermal rate is a set number of degree days between the emergence of successive leaves. The length of time that elapses between the emergence of two successive leaves on the plant is called the phyllochron. Late-sown crops have a shorter phyllochron, as leaves emerge faster and have fewer leaves overall.

Spring-sown barley produces fewer leaves than autumn-sown barley as the crop has less time to grow. On average the plant will produce eight leaves.

The production of tillers is key in the production of grain and ultimately grain yield. Tillers emerge after the third leaf has emerged on the barley plant. Shoots are produced from the tillers, so the more tillers that are produced, the more shoots are produced. The number of ears produced on the barley plant is dependent on the number of shoots produced. The higher the number of ears the greater the potential for a high grain yield.

The growth of the canopy is slow initially as leaves emerge on the barley plants. As leaves emerge the rate of photosynthesis increases as the plant can absorb more sunlight and the crop canopy expands rapidly. Once the ear emerges and the stem has fully grown, canopy growth ceases. The canopy absorbs most sunlight during the summer months. Canopy production can be maximized by ensuring the crop has sufficient nutrients to optimize growth during the summer period.

Until the stem begins to grow, all crop growth is at ground level. Once the stem starts to grow, the crop is more susceptible to frost damage at the growth point. Four of the leaves on the barley plant will grow at ground level and four will be on the stem. The crop will be at its maximum height after the ear emerges and biomass accumulation begins in the grains. At harvest the ear bends over and lies parallel to the stem. It is of benefit to farmers to choose a seed variety that is resistant to lodging to prevent stems breaking and reducing crop yield.

As the crop develops more leaves and has a bigger canopy, it increases the amount of sunlight it absorbs. In turn, the biomass it produces accumulates at a greater rate. Once the ear emerges on the plant, the leas senescence begins. Barley produces on average 13 t/ha dry matter at the time of harvest. Grain yield accounts for approximately 7 t/ha of this biomass.

The production of biomass goes through several different stages of production. Initially biomass production centers on leaf emergence. This is followed by stem production and ear production. Once the stem has reached its maximum height, biomass production is focused on grain production, as starch accumulates in the developing grains.

The greater the number of shoots produced, the greater the number of ears formed on the barley plant. Grain yield is determined by the number of ears per m². The crop ceases vegetative growth when ears start developing. It takes approximately 35 days for an ear to fully form on the barley plant.

Grains begin to fill once the ear has emerged. It takes approximately 40 days for the completion of grain filling in the barley ear. The products of photosynthesis, which were stored in the stem, are now transferred to the grains. Crop production can be maximized through adequate fertilizer application to ensure the maximum number of tillers on each plant, which in turn maximizes ear production and grain filling. The crop should be ripe before harvesting.