Carrot Climatic Requirements
Carrot is widely adapted to cool climates, but generally restricted to regions with low rainfall during summer and early autumn. A dry warm atmosphere is desirable for maturing plants. Seed production is suited to inland regions, away from coastal areas, where conditions are drier for maturing seed. The tropical type can be grown for seeds in plains but later produce seeds only under temperate climate. Both the types are adapted to cool weather and are highly resistant to frost. Temperate types undergo dormancy or rest period which can only be broken when the roots are subjected to a low temperature ie. less than 10 oC for a period of 4-6 weeks at any time either in storage or under field condition.
Land Requirements
Land to be used for seed production shall be free of volunteer plants. The soils of selected fields should be deep, with good drainage and fertility. Carrots do best in a deep, well-drained sandy loam or slightly acid loam soil. In heavy humus-rich soils carrots tend to have too much growth in the leaves and to form forked roots. Brackish soils should be avoided. A general recommendation is that 1000 kg of the fertilizer mix (2:3:4, N:P:K) per hectare should be worked into the soil before planting. A top-dressing of 100 to 200 kg limestone ammonium nitrate per hectare is applied about 8 weeks after sowing. Compost manure is not recommended. Carrots are intolerant towards a boron deficiency and in an area where it is known that there is a boron deficiency, boron could be applied with safety, because carrots are tolerant towards an excess of boron in the soil.
Isolation Requirements
Carrot is cross-pollinated by insects, including bees. A good nectar supply easily accessible attracts many insects. The seed fields must be isolated from other variety fields and fields of the same variety not conforming to varietal purity requirements of certification, by at lest 1000 meters for foundation seed production, and 800 meters for certified seed production. The detail is given in table 1.
Table: Distance specified for foundation and certified seed
| Contaminants | Minimum distance (meters) | |||
| Mother root production stage | Seeds production stage | |||
| Foundation | Certified | Foundation | Certified | |
| Field of other varieties | 5 | 5 | 1000 | 800 |
| Field of same variety not conforming to varietal purity requirement for certification | 5 | 5 | 1000 | 800 |
Method of Seed Production
Like other biennials both seed to seed and root to seed methods can be followed. Generally, the root to seed method is followed because in the seed to seed method root rot is usually very high, as compared to the transplanted roots. The whole roots with the tips cut (to examine the colour) are planted, keeping the crown exposed.
Cultural Practices
Root to seed method
First season - mother root production
Time of sowing
The sowing of seed crop should be done from 15th July to 7th August, depending upon duration of variety and climatic conditions.
Preparation of land
Carrots need deep, loose soil for their best development. Thorough pulverization of soil is essential. Prepare the field to a fine tilth by repeated ploughing, harrowings, followed by leveling.
Source of Seed
Obtain breeders/foundation seeds from source approved by a seed certification agency.
Seed Rate
Seed rate of carrot varies from 2.5 to 3.5 kg per hectare. The roots produced on one hectare are sufficient for transplanting 3 to 4 hectares under seed production.
Sowing of seeds
For better development of roots, sowing on ridges is preferred to flat sowing. Double row ridges 75 cm apart produce larger number of well-developed roots than single row ridges. The seed takes eight to 10 days for germination. For uniform germination, the ridges should remain moist till germination takes place. Hence, the field should be irrigated just after sowing. Afterwards, when the plants are 5 to 6 cm high, thin out plants to a distance of 6 to 7 cm.
Fertilization
Apply 15-20 tonnes of farmyard manure per ha to soil well before sowing, and mix it into the soil thoroughly. Apply 40-50 kg phosphorus and potash per ha at the time of sowing. Top dress once or twice with 75 to 100 kg ammonium sulphate per hectare, after weeding.
Irrigation : Irrigate at eight to 10 days interval as required.
Intercultural operation
Carrot is a slow-growing crop. Therefore, weeding and hoeing should frequently be done, particularly in the early stages. One earthing-up by end of September, or early October, will keep the crop clean till the close of autumn, when it is uprooted for planting.
Insect and Disease Control
Adopt recommended IPM methods
Harvesting of roots
Uproot the plants when they have fully developed roots.
Selection of roots for transplanting
Thorough selection of roots is made on the basis of character of tops, whether short or heavy, colour of skin, shape and size of roots. The colour of flesh, colour and size of the core are the most important characters to be considered. the core should be of the same colour as the flesh and as small as possible.
Field inspection
A minimum two inspection shall be made as follows
1. The first inspection shall be made after 20-30 days of the sowing in order to determine isolation, volunteer plant, outcross, off types and other relevant factors.
2. The second inspection shall be made after the mother roots have been lifted to verify the true characteristics of root.
Second season (seed production)
Planting of selected roots
After selection their tops are clipped and the tips pruned and then reset in a well-prepared field.
Brief Cultural Practices
Preparation of land:
Carrots need deep, loose soil for their best development. Thorough pulverization of soil is essential. Prepare the field to a fine tilth by repeated ploughing, harrowings, followed by leveling.
Method of transplanting:
The selected roots prepared in the manner already described r are reset in the field at a distance of 75 x 22.5-30 cms. The soil is then firmed and tapped around the roots. Soon after transplanting the field is irrigated.
Manuring:
Apply 20 tonnes of well-rotted farmyard manure well before sowing, and mix it in the soil thoroughly. At the time of final preparation mix in the soil 250-300 kg Super Phosphate and 100-150 kg muriate of postash per ha. Make surface application of 25-300 kg ammonium sulphate per ha during April to May after hoeing and earthing up.
Intercultural operation:
One weeding during March and another hoeing and earthin-up during April-May is required.
Other cultural practices are same as described for the previous season.
Field inspection:
A minimum of four inspections shall be made as follows
1. The first inspection shall be made before flowering in order to determine isolation, volunteer plants, outcrosses and other relevant factors (table 2)
2. The second and third inspections shall be made during flowering to check isolation, offtypes and other relevant factors
3. The forth inspection shall be made at maturity to verify the true nature of umbels.
Roguing
Roguing should be done at bloom stage. Early bolters and off-types should be removed from time to time as required.
Harvesting and Threshing : The best time for harvesting is when the secondary umbels (heads) are fully ripe and tertiary heads are beginning to turn brown. The crop ripens unevenly. Seed is commonly harvested by handpicking. Two to three pickings may; often be necessary. After drying, the heads are threshed and cleaned. After cleaning, the seed is rubbed by hand to remove the bristles on the surface and graded by means of sitters and sieves. Before storage, the seed moisture content should be reduced to eight per cent (Table 3).
Seed Yield
The average seed yield is about 500 to 600 kg per hectare.
Table 2: Specific requirement
| Factor | Maximum permitted | |
| Foundation | Certified | |
| Roots not conforming the varietal characteristics including forked roots | 0.10 % (by number | 0.20 % (by number) |
| Off types (plants) | 0.10 % | 0.20 % |
Table 3: Seed standard
| Factors | Standard for each class | |
| Foundation | Certified | |
| Pure seed (minimum) | 95.0 % | 95.0 % |
| Inert matter (maximum) | 5.0 % | 5.0 % |
| Other crop seeds (maximum) | 5/kg | 10/kg |
| Weed seeds (maximum) | 5/kg | 10/kg |
| Other distinguishable varieties (maximum) | 5/kg | 10/kg |
| Germination (minimum) | 60 % | 60 % |
| Moisture (maximum) | 8.0 % | 8.0 % |
| For vapour proof container (maximum) | 7.0 % | 7.0 % |
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