The Critical Period for Thinning Carrot (Daucus carota L.)

Field experiment was carried out at Impala Research station, in Botswana, aiming at investigating critical period for thinning of carrot (Daucus carota L.). The experiment was laid out in a complete randomized block design (CRBD), replicated three times and was repeated four times at different sowing dates. Seeds were sown at the same rate (3 kg ha-1) in all plots to obtain an equal plant population at initial stage, thereafter thinned at different times (2nd, 3rd, 4th, 5th and 6th weeks after emergence) to 30 cm between rows and 5 cm between intra rows to maintain constant population across the experiment. Days to maturity were constant from sowing to harvest in all the sowing dates. Plant height and yield significantly declined as thinning time was delayed. Number of leaves developed, root diameter and root length were not influenced by the thinning time. Vegetative growth and yield declined with the late sown experiments. It can be concluded that thinning time significantly increase plant height and yield, especially at earlier stages and carrot yield best when sown earlier in the season.