Maintenance breeding

Intellectual property rights(ipr

1. PRESENT ED BY: Pawan Nagar Reg. no.: 04-2690-2015 M.Sc.(Fruit Science) Maintenance Breeding

2. What are main activities of plant breeding? ( i ) varietal development:- it makes use of various plant breeding method(selection, hybridization, mutation and genetic engineering) to develop new variety. (ii) Seed multiplication:- it deal with multiplication of successive generation of various categories of seed. It regulated by seed certification agencies and breeders. (iii) varietal maintenance :- It deals with continuous fresh supply(annually) of breeder seed which used to start another cycle of seed multiplication .

3. INTRODUCTION The initial handful of seeds obtained from selected individual plants of a particular variety for the purpose of purifying and maintaining this variety, under supervision of a breeder. The varietal purity of subsequently multiplied foundation, registered and certified seed largely depend upon the quality of the nucleus/breeder’s seed. Unsatisfactory genetic purity, especially in cross pollinated crops, could ultimately severely affect the performance of a variety So it’s of very most importance to maintain the genetic purity and identity of n/s or b/s.

4. what’s maintenance breeding? A branch of plant breeding which deals with principles and method of breeder seed production and maintenance is called maintenance breeding. It’s a breeding procedure followed to maintain the genetic purity of the variety or parents of hybrid. it deals with principles and methods of breeder seed or nucleus seed production. It deal with ways and means of maintaining genetic and physical purity of released and notified variety. It’s also known as varietal maintenance technology.

5. Feature of maintenance breeding Continuous breeder seed production of released variety means fresh breeder seed production. It also undertake breeder seed production of parental line of released variety. Genetic purity, physical purity and germination are main point taken into account. Seed health also taken. Breeder and foundation seed is use as base material for starting MBP. It prevents varietal deterioration(mutation , cross pollination).

6. MAINTENANCE OF NUCLEUS AND BREEDER’S SEED. Methods of maintaining n/s or b/s can be divided into two groups: Maintenance of newly released varieties. Maintenance of established varieties.

7. MAINTENANCE OF NUCLEUS SEED OF NEWLY RELEASED VARIETIES 1.Selection and Sampling of the variety. Newly released variety are selected for nucleus seed production. These variety used as base material. These samples provide a beginning for purifying new varieties and for possible increase and distribution to farmers. Not more than fifteen new varieties in any one crop at a station should be sampled in one year. 2.Table examination of samples. Minimum 200 plants should be threshed separately. And examined in piles on the table. discard the off types. Left over seeds are now ready to be sown in a variety purification nursery called as nucleus.

8. 3.Locating and seeding of nucleus seed: Each nucleus seed should be grown in area in which this new variety could be grown, in the event of its release. The land must not have had a crop of the same kind in the previous year. 4.Inspection of nucleus seed plots and removal of off types: The nucleus plot should be examined critically from the seedling stage until maturity, Differences in the habit of early plant growth, other traits, diseases reactions should be critically examined.. If a plot differs distinctly from the average in the pre-heading stages of growth, it should be removed before heading.

9. 5.Harvesting and threshing of nucleus seed Each remaining plot, of which there should be at least 180 plant progeny out of the original 200 Should be harvested individually with a sickle and tied in a bundle. The total bundles of each nucleus should be labelled and stored until the current years yield test for trials are obtained. Discard if found unworthy After threshing seed should cleaned in fanning mill and placed in pile on seed table. Examine it for uniformity of seed appearance. Discard off type. Remain are bulk together and stored as breeder seed stock.

10. MAINTENANCE OF BREEDER’S SEED OF NEWLY RELEASED VARIETIES 1.Selection of field:- Breeder’s stock seed from the nucleus should be sown on the clean, fertile land, which did not grow a crop of the same kind in the previous year. Space required for seeding breeder stock is about 1.2 ha in wheat and 3 ha in transplanted rice. 2.The field should properly isolated. 3.Agonomic practices:- The best farm procedures should be used in the sowing, raising and harvesting of breeder’s stock. 4. It should be produced at the experiment station in the area in which the new variety has been bred. 5.Sowing:- Seeding done in such a way : 1.Best use of the limited amount of seed available . 2.Row spacing should be sufficient for examination of plant.

11. 6. Roguing: All unworthy plants of the variety should be pulled and removed like diseased, mechanical mixture, etc..The roguing should be done before flowering as well as after flowering for the nucleus/breeder’s stock seed. 7.Harvesting the breeder’s stock: The equipment used must be clean and free from seeds of any other varieties. This cleanliness should be extended to cards and bags as well as threshing machine it self. The seed should now be about 99.9 per cent pure as to variety. A portion of this breeder’s seed should be retained by the breeders for next cycle. Remaining distributed for F/S Production.

12. MAINTENANCE OF BREEDER SEED OF ESTABLISHED VARIETIES. A) By raising the crop in isolation:   The breeder’s seed of local varieties could be maintained by growing them in isolated plots and by rouging during various stages of crop growth. Method of handling of the breeder seed crop is same as breeder’s seed of newly released varieties.  B) By bulk selection:   In this method 2,000 to 2,500 plants typical of the variety are selected, harvested ,and threshed separately. The seeds from each plant are examined and any pile which shows off-type are discarded, The remaining piles of seed are bulked to constitute the breeder’s seed. The other practices of handling remains the same. 

13. Carry-over Seed  The breeder must carry-over at least enough seed to safeguard against, the loss of variety if there is a complete failure during the foundation seed multiplication phase. In addition, the breeder should further safeguard variety by arranging, to have a portion of the seed originally released stored under the ideal conditions.

14. Advantage of maintenance breeding It helps in purification of improved cultivars and parental line of hybrids. It prevent cultivars from genetic deterioration and so it prolong life of variety. It is useful in studying the efficiency of various maintenance procedures. It help in quality seed production which in turn lead to higher crop yield .

15. limitation of maintenance breeding Some maintenance procedure requires lot of experimental material of evolution. Large number of single plant have to be evaluated in term of agronomic performance hence Only limited number of cultivars can be handled at a time . Progeny row method require more time (2-3 season) for evolution of purity of a variety. Most of testing procedures are based on phenotypic performance only. Maintenance procedure are used for varietal purification. Hence chance of evolve new variety through MB are rare.