Seed Production of Root Crops
Root crops includes radish, carrot, turnip, beetroot & parsnip. The seed production technique is very specific technique in vegetable gardening. The seed production methods of different root crops are described below:
The seed of temperate types are produced only in the hills & tropical type in plains. It is a cross-pollinated crop & honey bees are main pollinators. Isolation distance of about 1000 m to 1600 m should be maintained between two varieties to produce pure seeds. There are two methods of seed production in radish:
- Root to seed method:
- Seed to seed method:
Root to seed method:
This method is employed to produce quality seeds. This method cannot be adopted in European type because they do not stand transplantation well. In this method radish is harvested when roots are fully matured during mid-November to mid-December. True to the type roots are selected on the basis of root color, shape & size etc. and transplanted after cutting 1/4th of the lower portion of root. The top leaves are then trimmed (1/3rd) without injuring to the crown. Then, they are transplanted in a fertile soil at wider spacing 90 cm * 15-20 cm. irrigation should be given immediately after transplanting. Subsequently irrigation is given at any interval of 7-10 days till seed are formed in the pods.
Spraying of GA3 at 100 ppm after transplanting increase the percentage of flowering in pusa himani, Japanese white, etc. Since there is no natural dehiscence (shattering of seed), the pods are allowed to mature & ripe fully in the field before they are harvested. The seeds are ready in April. When most of the pods (70%) are brown, the seed stalks are cut & kept in small piles to dry in open. Seeds are extracted by threshing. The seeds are then cleaned, dried in the sun & graded properly.
- Thorough examination of roots for off type roots is possible.
- Production of seed of highest quality.
- Selection of good quality roots for transplantation.
- Lower seed yield.
- Consumption of more labor and time for uprooting, preparation of stecklings etc.
- Root rot causing micro-organisms may enter the roots through the cut surface.
Seed to seed method:
In this method radish plant with root is left in the field and allowed to produce seed stalks. This method is not recommended for production of high quality of seeds because the selection of good roots cannot be made and off type plants which are not true to variety cannot be rogued. Average seed yield in this method is about 600-800 kg/ha.
Asian types are annual whereas temperate being biennial remains vegetative in the first year and becomes reproductive in the following growing season. Biennial types require low temperature i.e. around 4-10 degree Celsius for bolting. Just like in radish, in carrot also root to seed & seed to seed method is used for seed production.
Only the Asiatic varieties produce seeds in plains. The European varieties seed production is limited to hills only. Since, it is a cross-pollinated crop, every care should be taken to keep the two varieties away from each other and the isolation distance to produce pure seed is 1000 m -1600 m. Asian type varieties seeds are sown during August – September in plains whereas European type varieties seeds are sown during July-August in hills.
Usually, good quality and high yielding roots (Steckling) of a variety are selected at the root marketable stage & transplanted to the well-prepared fields after giving proper root & shoot cut to ensure better quality & higher seed yield. The selected roots are planted at the distance of 75 cm * 10-30 cm.
The seed crop is harvested when the second order (secondary) umbels are fully ripped and third order umbels have started to turn brown. After harvesting umbels are cured for 5-15 days. Seeds are then threshed, cleaned & packed. A yield of 300-500 kg seeds per hector are obtained from European varieties while 1200-2500 kg/ha seeds is produced from Asiatic varieties.
The method of seed production is same as that for radish. The seeds of the tropical types are produced in the plains whereas those of temperate types are produced in the hills. It can cross easily & readily with mustard, radish etc so, proper isolation distance of 1000-1600 m is necessary to maintain.
Seed to seed method:
In this method turnip plant with root is left in the field and allowed to produce seed stalks. This method is not highly recommended for production of high quality of seeds because the selection of good roots cannot be made and off type plants which are not true to variety cannot be rogued in timely.
Root to seed method:
It is similar to that of radish where selected roots are transplanted with abundant supply of water, manure & required cuttings before transplanting. Spacing is maintained at 90 cm * 15-20 cm. When most of the pods (70%) are brown, the seed stalks are cut & kept in small piles to dry in open. Seeds are extracted by threshing. The seeds are then cleaned, dried in the sun & graded properly as like in radish.