Introduction
The carrot (Daucus carota var. sativus) is part of the Apiaceae family. It is thought to have originated in the Middle East around the 10th century before being introduced into Asia and Europe in the 16th century where todays orange variety began its popularity. Carrots grow in a multitude of colours, from white, yellow, shades of pink and purple to black, though these varieties have had substantially less development and breeding effort resulting in less than favourable grower and consumer-valued qualities. The carrot was New Zealand’s third largest vegetable seed crop in 2012 with an export value of $17.8 million (Freshfacts, 2012) and is still a major production crop in the ...view middle of the document...
5). Over crowding can lead to deformed roots and stunted growth (Origin, area, production, varieties, package of practices for carrot).
The epicotyl elongates and straightens and foliage develops, beginning the process of photosynthesis creating energy for the tap roots growth in length and increase in diameter, storing vitamins and minerals as it does so. The primary function of the tap root is as a reserve of nutrients for the production of flowering as carrots are categorically biennial, requiring two years to produce umbels and seeds but they are grown as an annual for their fleshy edible root.
Cultivation
There are two different methods to produce carrot seeds depending on the objective. If there is confidence that the carrot crop can produce a ‘genetically uniform crop without root selection’ (Principles and Practices of Organic Carrot Seed Production, pp. 4), then this seed-to-seed method would be the more efficient method to choose, producing a higher seed yield. Alternatively there is the root-to-seed method, which entails uprooting each carrot and replanting only the ones that have desirable characteristics, therefore improving quality and specific traits. A minimum of 200 plants is suggested for both methods to retain genetic variation and integrity in crops. As the foliage grows, each plant benefits from being staked, providing support to prevent it from lodging.
Seed-to-seed method
Large-scale production is usually done using the seed-to-seed method, with the carrot crop planted towards the end of summer and left in the ground through winter until the following autumn. Exposure to this cold is required to vernalize the crop so it can generate flowering come the second summer. Carrots are cold and frost tolerant down to approximately -10 ºC providing there is not excessive freezing and thawing for a sustained period of time (Principles and Practices of Organic Carrot Seed Production, pp. 6). New Zealand’s weather provides optimal conditions for the carrot seed crop, with cool winters that encourage bolting, and warm, dry summers that support pollination.
Root-to-Seed method
In climates with sub-optimal winter temperatures the root-to-seed method is often used with the crop being planted in early spring and harvested in autumn. Carrots are then put through a selection process where only the preferred roots are chosen to contribute their traits to future crops. If the winter is no colder than -10ºC then the carrot may be replanted straight way, spending the winter in the field, otherwise suitable storage is required until the following spring. ...
