Response of Carrot 'Daucus carota' L. to Soil Compaction and Mulching

Abstract

Carrot ('Daucus carota' L.) is a popular root vegetable known as a source of vitamin A. The market value of fresh carrot roots is determined by the shape and size of the storage roots and soil impedance is a major determinant of these properties. Two experiments were conducted in the glasshouse in July 1985 and in April 1986, to study the response of carrots to soil bulk density, water regime, mulching, and manure application. Yield parameters including the storage root and tops fresh weight, the storage root : tops fresh weight. ratio, the storage root length, and carrot shape as a quality parameter, were measured and analysed statistically in both experiments. The first experiment was carried out to study the effect of soil bulk density and water regime on carrot yield harvested at different growth stages. The effect of mulch, manure, and water regime on final yield and shape were studied in the second experiment.In the first experiment, pre-germinated hybrid-4 carrot seeds were grown in PVC pots at four bulk densities (1.25, 1.40, 1.55, 1.70 Mg m⁻³), with two watering regimes (high and low). The plants were harvested 68, 103 or 153 days after planting. The length of lateral roots and the soil strength as estimated by the cone penetrometer, was measured in this first experiment. In the second experiment, using polystyrene boxes as containers, the carrots were grown under rice straw, white and black plastic mulches, and in bare soils. In addition, the effects of two watering regimes and manure applications on carrot yield harvested 100 days after planting, were studied under these mulch conditions. Total water applied, water use efficiency, and soil temperatures at three different depths (the soil surface, 5 cm, and 15 cm) were recorded in the second experiment.