Local Varieties
Local varieties are nothing but traditional varieties but which are susceptible to diseases and pests and are having long duration for maturity. In case of rice – Krishnakatukalu, Basangulu.
High Yielding Varieties
High yielding varieties are dwarf varieties and having short duration with resistant to pests and diseases with maximum yield potential.
Eg: I.R -64, I.R – 36, I.R – 50.
Hybrids
A systematic and extensive evaluation of the experimental hybrids, across the country, at the twelve research net work centers has been taken up. About eight hundred experimental hybrids have been evaluated so far.During the wet season ( Kharif), the experimental hybrids are being evaluated at 12 centers, where as during dry season ( rabi ) the experimental hybrids are evaluated in seven centers, located in southern, western and eastern India. Very useful information on performance of hybrids and data on yield and yield components and other auxiliary characters of hybrids across the locations and seasons has been collected over the years.
As a result of concerted, goal oriented, time bound and co-ordinated efforts for the first time in the country, four rice hybrids were released for commercial cultivation during 1994, by the state variety release committee. These are APHR-1 and APHR- 2 for the Telangana and Rayalaseema regions of Andhra pradesh, MGR-1 for the Tamilnadu state and KRH-1 for Karnataka state. Subsequently two more hybrids, viz., CHRH -3 and DRRH-1 were released recently.
Genetically Engineered Seeds
One of the major concerns of cultivating hybrid varieties is that farmers can not use seed from the harvest for their next crop and thus have to buy new seed for each crop. More-over, the cost of hybrid seed is 5-20 times more than that of seeds of inbred varieties.Possibilities for true -to- type multiplication of hybrid rice are being explored through two approaches. Production of artificial seeds through somatic embryogenesis and
Development of apomictic hybrid rice through wide hybridization and genetic engineering techniques.
Production of Artificial Seeds And Mass Propagation of True- Breeding Hybrids
Artificial seeds, consisting of somatic embryos, enclosed in a protective coating, are being proposed as low-cost, high-volume propagation system. The objective is to produce clonal seeds at a cost comparable with that of producing hybrid seed by conventional methods. Artificial seeds can be produced through somatic embryogenesis. This is the process by which somatic cells develop through the stages of embryogeny to give whole plants without gametic fusion. Somatic embryogenesis has been reported in more than 150 plant species. Somatic embryos have been induced from a variety of plant tissues, such as germinating seedlings shoot meristems, young inflorescence, nucellus, leaf, anther, root and others.
Artificial seed technology involves various steps for the production of somatic embryos and their utilization as commercial propagules.
Optimization of somatic embryogenesis system from cultured cells
Optimization of embryo maturation.
Automation of embryo production.
Production of mature synchronized embryos.
Encapsulation of embryos with necessary adjuvants.
Coating of encapsulated embryos.
Optimization of green house and field conditions for conversion of embryos into plants. And
Delivery system for artificial seeds.
Tissue Culture
“It is the process of growing tissue or cells which are exercised from healthy plants. These tissues are grown on nutrient medium under aseptic conditions.”
It is also called as micro propagation. Tissue culture involves several techniques which are
Anther culture
Embryo rescue or ovary culture or Embryo culture.
Protoplast culture and protoplast fusion.
Somatic embryogenesis.
To develop a straight variety or true to type variety in crop plants, pure line selection method is adopted. In this method the seeds of pure lines are selected from homogeneous population of a particular crop and multiplied in the next season. This multiplication process is conducted in different co-ordinated centers and performance of the pure lines is tested. If the performance is good then the state varietal release committee or central varietal release committee releases the variety of that particular crop.
The seed supplied from Agricultural Research Stations, Department of Agriculture, or A.P. State seed corporation is not adequate to meet the requirements of the farmers. So the private seed producers are actively engaged in multiplication and supply of seed to the farmers. But the cost of seed is some times high and the quality also is not maintained. Hence, the farmers are motivated to develop their own seed in respect to varieties.
A seed village concept was introduced and the farmers were encouraged to develop their own seed. In this process the farmer is supplied with limited quantity of foundation seed or certified seed by Research stations or A.P State seed corporation. The farmer will grow variety with the seed supplied in a limited area with good management practices of both plant husbandry and plant protection. He is also provided with information of the characters of the variety like duration, grain type, the time of panicle initiation etc. He observes the crop from time to time, and the off-types will be removed as and when noticed. He maintained a homogenous type of plants having the varietal characters . while harvesting he eliminates 1 meter crop from all sides of the field to avoid contamination from other varieties grown in neighbor hood and threshed, separately with all the care to prevent admixture of other varieties in threshing floor.
Like wise care will be taken during storage to maintain purity. Such seed will be used continuously year after year for the period of 3 to 4 years. Such seed can also be spread to the co-farmers interested in that specific Variety. After 4 years the farmer can again secure foundation seed or certified seed from the Research station. If it is practiced by atleast 25% of the farmers there will not be any scarcity for pure good seed.
