Seed Health Management for Better Productivity - Govind Ballabh ...

(Seed Health Management for Better Productivity)4. Seed StandardsIn India standards for foundation and certified seeds have been prescribed. There are twotypes of standards, i) field standards which apply to the standing crop, and ii) seed standardswhich are applicable at seed level. Field standards includes requirement isolation distance,maximum permissible level of off types, inseparable other plants, objectionable weed plants,pollen shedders (in male-sterile or A lines), plants infected by seed borne disease etc. Seedstandards relate to genetic purity, physical purity, germination, other crop seeds, weed seeds,moisture content etc.Standards for breeder seed have not been prescribed but breeder seed has stricterstandards than those prescribed for foundation and certified seeds. Breeder seed must be 100%genetically pure.5. Isolation Distance for Seed CropIsolation is essential to avoid mechanical mixture during harvesting or collection of produceand out crossing. In strictly self-pollinated crops it is mainly to avoid mechanical mixture fromadjoining plots. Isolation requirements in cereal crops like wheat and paddy is 3 meter.Sources of contamination could be other varieties of the same crop, same variety notconforming to varietal purity requirements of the category of seed under production, other crops(mustard and turnip; maize and teosinte) or weeds. In wheat isolation requirement from othervarieties is only 3 m, whereas isolation from fields of wheat, triticale and rye of infection of loosesmut in excess of 0.1% and 0.5% is 150 m in case of foundation and certified seed.6. Time of SowingSeed crops are generally sown at their planting time as recommended for commercialcrops. However, depending on incidence of diseases and pests, and monsoon, some adjustmentin sowing time could be made. Care should be taken that monsoon do not coincide with theflowering, seed filling and seed maturity stage, especially with kharif crops.7. Method of SowingThe seed crop should be sown in lines with a seed drill/ planting equipment. One directionsowing helps in cultural operations and inspection. Before and after sowing a variety, the seed drillmust be subjected to thorough cleaning of pipes, seed cups and box. The seed crop must be sownin such a way that it facilitates the movement of the personnel to execute roguing effectively.Skipping one row after every eight to ten rows or more may provide sufficient path for movementduring roguing in wheat seed crop. Similarly, paired row planting in rice, green gram and chickpeais very useful. In crops like maize, pearl millet, sorghum, pigeon pea etc. the row to row spacing iswide enough for the purpose of roguing.8. Cultural PracticesCultural practices such as seed bed preparation, fertilization, weeding, irrigation etc. areusually the same for seed crop as recommended for commercial crop. All recommended- 107 -