In this two-part article we will look at the different aspects that plays a role during carrot crop establishment
AGRI-PULSE - NORTH WEST - A key factor in maximising the yield of carrots, is promoting the establishment of rapid and uniform crop.
Early leaf growth and establishment of a strong root system will help minimise crop variability. Getting optimum carrot establishment relies on good pre-sowing planning, followed up with careful post-sowing crop management. An uneven crop complicates these management practices and can ultimately lead to loss of yield.
Carrot seeds.
Carrot seeds are very small, and while they have the energy required for germination, the embryo inside has not fully formed when the seed is harvested. The embryo is very important as it will develop into the first leaves and root shoots of the carrot plant. As a result, carrot seeds require some time before germination, while the seed prepares its embryo for early plant growth. Seeds can be graded based on the embryo size and this will help improve the uniformity of germination. Using graded seed has been shown to significantly influence variability in seedlings at establishment. Stable moisture content around the seed is of utmost importance and care should be taken with irrigation scheduling.
CONFIGURATION AND PLANT DENSITY
Row configuration and plant spacing should maximise access to light, water and nutrients. Plants in the outer rows will have greater access to these elements and be bigger/longer than those carrots from the inner rows. To compensate for this effect, outer rows may be planted at a higher density to even out the final root size.
Optimizing row configuration and density for specific growing conditions is vital for best harvest. The optimum planting density will vary between growers and should be set based on planting equipment, block configuration and the market they are supplying. The planting density will dictate the size and quality of the final taproot.
Seeding rates should be calculated based on the final plant-density and needs to consider seed germination percentage and the possibility of field losses (due to environmental factors) during establishment. Uniform seed size will help improve accuracy of seed placement efficient movement through the seeding equipment.
HOW TO DETERMINE THE SUITABLE PLANTING DENSITY
As an example, a grower is targeting a final plant population of 90 plants per m2. The seed germination is 95% and the establishment rate, considering post-sowing field losses, is 70% (i.e. 30% of the seed planted is lost due to insect or wind damage). What rate (seed per ha) should the carrot seed be sown at?
1. Final population (per m2) x 10 000 =Final population (per ha) 90 x 10 000
= 90 000 plants/ha
2. Planting density = (Final population /Germination%) X
100 000/establishment %
= (90 000 ÷ 95) X 100 000/70
Planting density = 1 353 383 seeds/ha
