The production of certified seed differs from crop to crop to some extent. There are some common steps which are involved in the certified seed production of various field crops.
The common steps include:
(1) Package of practices,
(2) Isolation distance,
(3) Plant protection measures, and
(4) Roguing.
These are briefly discussed below:
Step # 1. Package of Practices:
Standard agronomic practices, viz. sowing time, spacing, fertilizer dose, hoeing and weeding are available for each crop. These cultural practices have to be strictly followed to raise a good crop. It is essential to harvest good yield and better quality of produce.
Hence, recommended agronomic practices should be adopted for production of quality seeds. Proper crop rotation has to be adopted to avoid contamination from previous year’s crop variety. The seed production should be taken up under irrigated conditions to ensure high yield and good quality.
Step # 2. Isolation Distance:
Isolation refers to the separation of the field of a variety from that of another variety of the same crop to avoid contamination. Proper isolation distance should be maintained to avoid contamination through natural crossing. The isolation distance differs from crop to crop for the production of foundation and certified seeds (Table 40.2).
The isolation distance is low in self-pollinated species, moderate in often cross pollinated species, and high in cross pollinated species. In some self-pollinated species like wheat, barley, oats etc., isolation distance of only 3 metres is required, whereas in cross pollinated species like cabbage, cauliflower, radish, sugar-beet etc. isolation distance of 1600 metres is required for the production of genetically pure seed.
Step # 3. Plant Protection Measures:
It is essential to protect the seed crop from the attack of various insects and diseases, because attack of both insects and diseases leads to significant reduction in yield as well as quality of seed. Hence, recommended plant protection measures should be adopted to raise a healthy crop.
Step # 4. Roguing:
The process of removal of off type (phenotypically different) plants from the field of an improved variety is known as roguing. The main objective of roguing is to avoid contamination through mechanical mixture and due to outcrossing. In self-pollinated crops, generally roguing is done at three different stages, viz. before flowering, after flowering and before harvesting.
The characteristic features of the variety are taken into account during the process of roguing. Any plant deviating from the features of the variety under multiplication is removed. In the production of hybrid seed in cross pollinated crops, roguing should be completed before flowering. In self- pollinated species, roguing can continue even after flowering. The diseased plants should also be removed to prevent the spread of disease. In hybrid seed production, roguing is done in both seed parent and pollinator parent.
Field inspections are made by the inspectors of State Seed Certification Agency to examine the suitability of crop for certification. The number of field inspection varies from 2 to 4 depending upon the crop species (Table 40.3). When only two inspections are made, one is made during flowering and another before harvesting.
In case of three field inspections, one is made before flowering, second at the time of flowering and third before harvesting. In case of four inspections, one is made before flowering, one at the time of flowering and two between flowering and harvesting.
The main objective of field inspections is to examine:
(i) Isolation distance,
(ii) Off types,
(iii) Objectionable weeds,
(iv) Disease and insect incidence, and
(v) General crop condition.
The off types should not be more than the maximum standard prescribed for. The maximum off type plants in the seed plot of foundation and certified seed plot are permitted from 0.05-1 %, depending upon the crop species.
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