Introduction
Carrot (Daucus carota) is a leading root vegetable in India. It is consumed as salad, juice, and also in cooked form. It is also made into mixed vegetable pickles as well as sweets and carrot puddles are prepared, which are relished by one and all. Carrot juice is a rich source of carotene, lycopene, anthocyanis and is sometimes used for coloring other food items and edibles. Carrot roots are rich in carotenoids. The predominant carotenoid in orange carrots is ß-carotene (provitamin A). The 100 g of carrot root contains 8,285 µg ß-carotene, 320 mg potassium, and 2.8 g of dietary fiber. Black Carrot is a rich source of anthocyanins and is used for the preparation of a beverage called Kanji that is considered to be a good appetizer. Carrot originated from Southwest Asia (especially Afghanistan). The main carrot-growing states are Uttar Pradesh, Asom, Karnataka, Andhra Pradesh, Punjab, and Haryana.
Table of Contents (toc)
Climate and soil
Carrot is a cool-season crop, though some of the tropical types tolerate quite high temperatures. The optimum temperature for growth, yield, and quality of root is about 10-25°C. Orange color in the roots accumulates best at 15.6-21.1°C; color development and growth of roots are influenced by temperature. Carrot can be grown on all types of soils. But it thrives best on a deep, loose loamy soil. For an early crop, sandy loam soil is preferred and for high yield, deep, loose, loamy soil is desirable. Long, smooth, slender roots desired for the fresh market can be grown successfully on deep well-drained light soils. Carrots grown on heavy soils are rough and coarser than those grown on light sandy soils. The soil pH of 6.5 is ideal.
Varieties
There are 2 distinct groups of carrots cultivated in the world-tropical or Asiatic and temperate or European. The temperate types form roots both under temperate and tropical climates but set seeds only under temperate conditions since they need a low temperature of 5-8°C for 40-60 days before flowering to break root dormancy. The Asiatic types are high-yielding and produce seeds under tropical conditions. In the recent past lot of improvement work has been done at IARI from quality, maturity and abiotic stress resistance especially heat tolerance point of view. As a result, IARI has released during the last 5-6 years a large number of improved varieties and hybrids employing the CMS system. A wide range of colors from black and red to yellow is found in this group. Important varieties commonly grown in the country are discussed here.
Tropical or Asiatic types
The major tropical varieties are listed below.
Pusa Asita: First black color carrot variety in the country. Roots are long, smooth, round-shouldered black color self-core and obtriangular shape, suitable for sowing from September to October in north Indian plains. Roots are ready for harvest during December January, taking 90-110 days from sowing. The average foot yield is 25 tonnes/ha.
Pusa Kesar: It has red color roots and a self-color core. Suitable for early sowing (from August to early October), taking 90-110 days from sowing. The average root yield is 25 tonnes/ha.
Pusa Kulfi: It is the first cream color self-core tropical carrot variety. It is suitable for normal sowing beginning mid-September under north Indian plains. It attains marketable maturity in 90-100 days. The average root weight is 100-150 g with about 25 tonnes/ ha root yield.
Pusa Meghali: Its roots are orange with self-color core with short tops. It is the only variety having orange flesh in the Asiatic group. Suitable for early sowings (August-September), taking 90-100 days to marketable stage from sowing. The average root yield is 25 tonnes/ ha like other Asiatic group carrots, which produce seeds in the plains.
Pusa Rudhira: Roots are long blood-red in color. attractive obtriangular shape, self-color core, suitable for sowing from mid-September to October. The roots are ready for harvest during December-January, taking 90-110 days from sowing. The average root yield is 30 tonnes/ha.
Pusa Vasuda: First public sector tropical carrot hybrid developed using CMS system. Roots are red, smooth, attractive, vigorous, self-color core, sweet, juicy, rich in total carotenoids, lycopene, TSS, and minerals. Suitable for salad, juice extraction, cooking, and carotenoids extraction. Takes 80-90 days to maturely with an average yield of 35-40 tonnes/ha.
Pusa Vrishti: First heat- tolerant, tropical, red-color variety. It is suitable for early sowing beginning in July end the first half of August under north Indian plains. Roots have a red color core. The average root weight is about 150-200 g. It takes about 90 days to attain marketable maturity and gets ready by mid-November. The average root yield is 20-22 tonnes/ha.
Temperate or European types
The major temperate varieties are listed below.
Nantes: It is an old introduction, roots are small, orange, cylindrical 12-15 cm long, fine-textured, abruptly ending with a small thin tail, small leaf tops. It gets ready for harvesting in 90-100 days from sowing. The average root yield is 25-30 tonnes/ha.
Pusa Nayanjyoti: First temperate hybrid developed by the public sector with orange-colored roots. It is a CMS-based hybrid. Roots are orange, smooth, uniform, cylindrical, stumpy with a small indistinct self-color core. The sowing is done from April-August in the hills and during November-December in the north Indian plains. The average root yield is 39.6 tonnes/ha.
Pusa Yamdagini: Roots long, slightly tapering, cylindrical with small tops and orange flesh with the self-color core. Sowing is done in hills from April-August. It gets ready for harvest in 90-100 days and yields 20 25 tonnes/ha.
Cultivation
Land preparation
The field should be ploughed deep to a good tilth. If the soil is not thoroughly prepared and contains clods, quality roots cannot be produced. Root deformity usually occurs in fields that are under-prepared. The land surface should be as smooth as possible before sowing. Excessive tillage should be avoided since it is costly and affects soil structure adversely.
Sowing
Carrot seeds are directly sown in well-prepared beds or fields on ridges 45-60 cm apart. In the northern Indian plains, the tropical types should be sown from August to early October, and temperate types in September to November and January to March. In hills, March-July is the sowing time. In the south and central India, seeds are sown during January-February, June-July, and October-November. Successive sowings at 10-15 days intervals ensure a continuous harvest. Shallow sowing about 1.5 cm deep gives good germination. Germination is slow and usually, 10-20 days are required for seedlings to appear. It is desirable that at the time of sowing sufficient moisture should be there or light irrigation should be given immediately after sowing. It is better to soak the seeds in water for 12-24 hr before sowing to hasten germination. The seed at a rate of 4-5 kg/ha is optimum.
Manuring and fertilization
Application of 20 tonnes of well-rotten farmyard manure, 70 kg N, 40 kg P, and 40 kg K/ha is optimum. In the absence of organic manure, application of 80 kg N, 60 kg P, and 60 kg K/ha gives a good yield. Apply half of the N and a full dose of P and K before sowing. The rest of N should be top-dressed 45-50 days after sowing.
Aftercare
Carrots do not compete well against weeds. Thinning should be done for proper development. The seedlings are thinned to a distance of 4-5 cm. The seedlings grow slowly at first, and cannot compete with weeds. Remove weeds especially in the early stages. The soil should be hoed occasionally to allow proper aeration. To control the weeds, spray [email protected] liters/ha immediately after sowing. Care should be taken that there is proper moisture at the time of application of weedicide. If moisture is less, light irrigation can be given.
During weeding and hoeing, the crown of the root is often exposed to light. This causes greening and lowers the quality of roots. For proper development of roots, one earthing-up may be done during root formation.
Irrigation
After sowing keep the ridges moist till the germination completes. Irrigate at 8-10 days intervals before wilting of leaves starts. Usually, light irrigation is given 2-3 days before harvesting for easy uprooting. Insufficient moisture and excess water have adversely affect on yield and quality of roots.
Physiological disorders
Physiological disorders are often a response to the lack or excess of essential crop nutrients or other factors unfavorable for growth. Such factors could be a lack or excess of light, moisture, or temperature. Other possibilities may be poor soil structure, poor aeration, soil compaction, high soil salinity or air pollution. These are described below.
Splitting or cracking
It is a major problem in carrot-growing regions. Although the tendency of splitting seems to be controlled by genetic factors, a number of other factors may be involved. The splitting is reduced by low N and increases as the amount of N in the soil increases. High soil concentrations of ammonium compounds cause more serious splitting than by other forms of N. Carrot splitting is not affected by the time of planting or variety. Wider the spacing, the greater is the amount of splitting and large roots are more likely to split than small ones.
Root forking or hanging
It is an important defect that reduces the marketability of roots. The occurrence is often due to early damage or obstruction of the taproot apical meristem resulting in a shortened tap root associated with the formation of branching of secondary storage roots producing a distorted, multiple-rooted organ. Abiotic factors such as buried crop debris and rocky or compacted soils are implicated as contributory causes. Nematodes, fungi, and insect feeding injuries can also cause deformed and forked roots.
Harvesting and post-harvest management
The Asiatic carrots attain the marketable stage of maturity when they are 2.5-4 cm in diameter at the upper end. Delay in harvesting makes roots fluffy and unfit for consumption. Early carrots for the market are pulled out when partly developed. They are normally dugout, with a spade or khurpi when soil is sufficiently moist. The roots are trimmed and washed before sending them to market. Generally, Asiatic types produce a higher yield (25-30 tonnes/ha), whereas European types produce around 18-20 tonnes/ha.
Fresh carrots cannot be stored for more than 3-4 days under ordinary conditions. However, long-term storage in cold stores is possible without appreciable change in quality, especially in temperate types. At temperatures of 0-4.5°C with 93-98%, relative humidity carrots can be stored for 6 months. Storage at 98-100% relative humidity results in less decay than at 90-95%. At higher humidity moisture loss is considerably less. As a result, the carrots remain crisper, firmer, and of better color. The optimum temperature for minimizing decay is 0-1°C. There is no change in organoleptic properties of carrots stored in crates covered with perforated plastic films at 0°C and 93-96% relative humidity for 7-8 months.
