**4. Three tier system**

The AICCIP centers for various crops are located at ICAR institutes or State Agricultural Universities (SAUs) or other volunteer centers recommended by AICCIP workshop based on covered crop area, adaptability, and agro-climatic condition etc. It involves various steps [6].

#### **4.1 Initial varietal trial (IVT)**

The time duration of the initial varietal trial (IVT) is one year. All the entries, which were superior to their respective station trials, would be introduced into the IVT. These entries would be used for multi-location trials along with checks. In general, three checks (national, zonal and local checks) are being used for efficient evaluation of entries across the centers. The national check (a crop variety which had been released previously for whole country) would be used for a long period but zonal (a crop variety which had been released previously for specific zone) and local checks (high yielding local variety) can be replaced based on the requirement. These checks cannot be replaced after the IVT. Maintenance of genetic purity, germination and physical purity of new material are the prime objectives of the concern plant breeder/agency. The IVT trials are conducted in such a manner that minimum difference of yield (5–10%) and other ancillary traits can be measured. Experimental layout (experimental design, number of replications and treatments) is the prime responsibility of the PC/PD through concerned principle investigator. The cultural practices *i.e.* seed rate, date of sowing, row to row and plant to plant spacing; weed, fertilizer and water management etc. shall be strictly followed by the IVT centers as per guideline of PC/ PD. The plot size of IVT is smaller than advanced trials. An IVT includes the maximum number of locations across the country to evaluate varietal adaptation and performance. The number of testing locations varies with crop across the zones. A team of scientists (plant breeder, agronomist, pathologist, entomologists etc.) will monitor all the trials as per the recommendation of the PC. Project coordinator constitutes monitoring teams (includes scientists from various disciplines such as plant breeding, agronomy and plant protection) for evaluation of trials. Each member of monitoring team submits their report to the PC based on their observation during trial monitoring. Each crop has different objective and requires different technical requirement for their evaluation. For example, The IVT centers will generate information related to days to flowering, physiological maturity, plant height, lodging, threshability, disease, and pest tolerance, green fodder yield, dry matter yield, and nutritional quality traits for forage crops. Technical program is formulated during workshop or national group meet and PC will specify characters on which data shall be recorded. Entries which are superior over the best check in terms of yield and other related traits will be promoted into the advance varietal trial-I. The superiority is primarily decided based on yield potential and other related important traits such as quality traits. In some agricultural crops, where a large number of entries enters into the IVT system then; IVT is preceded by testing of these entries for one year in the National Screening Nursery.
