I. Object

To determine the genetic purity of a given seed lot of a released cultivar and the extent to which the submitted sample conforms to the prescribed standards. 

II. Sampling

The samples for grow-out test are to be drawn simultaneously with the samples for other quality tests and the standard procedure shall be followed.  

The size of the submitted sample will be as follows;  

1000grams: for Maize, Cotton, Groundnut, Soybean, and species of other genera with

                  seeds of Similar size. 

500grams: for Sorghum, Wheat, Paddy and species of other genera with seeds of similar size

250grams:For Beta and species of other genera with seeds of similar size. 

100grams: For Bajra, Jute and Species of all other genera.

250 tubers/planting stakes/roots/corms - Seed potato, sweet potato and other vegetatively propagating crops.

III. Procedure

While raising a test crop, standard and recommended agronomic/cultural practices (e.g., field preparation, size of the plot, row length, distance between rows, distance between plants, irrigation, fertilisation etc.), in respect of individual crops are to be followed both for the unknown sample and its control.  

The possibility to prove the genuineness of a cultivar by grow-out test is based on hereditary characteristics of the plants. Usually the cultivar differences are more distinct if growth conditions are favourable. Crop should be so grown that the genetical differences express themselves as clearly as possible. In self-fertilising species the individual of a cultivar may be theoretically identical whereas the individual of a cultivar in a cross-fertilising species may not be genetically similar, but comprise a number of types. Therefore, it is easier to determine the cultivar purity in self-fertilising species than in cross-fertilising species where the examination of greater part is based on the mutual comparison between the sample to be tested and the standard sample. Hence, it is essential to sow the various samples of the same cultivar in succession and standard samples are sown at suitable intervals (for example one standard sample for every ten samples to be tested). The size of plots, row length etc. will differ crop to crop. However, the specifications for different crops are indicated in the following table. The Certification Agency may change the specification if considered necessary.      

Sl. No.    Crop                                        Row        Plant        Space        Space         No. of

                                                               length      to plant     between     between      replications

                                                              (meters)   distance    rows          plots

                                                                                (cm)        (cm)          (cm)

1.    Wheat, barley, oats                            6                2            25                50              2

2.    Pea, cowpea                                      6              10            45                90              2

3.    Chickpea, green gram, black gram      6              10            30                60              2

4.    Maize                                               10              25            60                90              2

5.    Hybrid cotton                                     5              10            45                45              2

6.    Paddy

       a. very early to medium                       6              15            20                45              2

       b. late and very late                             6              25            30                60              2

7.    Pearl millet                                          6              10            60                90              2

8.    Sorghum                                             6              10            45                60              2

The seed rate may be adjusted depending on the germination percentage of individual sample and the sowing may be done by dibbling.  Subsequent thinning is not recommended.

The test crop may be raised along with the control either in all the areas recommended for the variety or in off-season nurseries. The authentic control sample from the originating plant breeder/breeding institute is to be maintained by the testing station / agency following standard procedures. A minimum of two hundred plants from control sample will be raised along with the test crop.

IV. Observation

(a) All plants are to be studied keeping in view the distinguishing characters described for the cultivar both in the test crop as well as the control. Necessary corrections may be incorporated if the control is found to be heterogeneous.

(b) Observations are made during the full growing period, or for a period specified by organising breeding institute and deviations from the standard sample of the same variety are recorded. At suitable development stage the plots are examined carefully, and plants which are obviously of other cultivar are counted and recorded.

The specifications of the field plot, row length etc. may be determined from the information given in para III above and on the basis of the number of plants required for taking observation is dependent on maximum permissible offtypes which are as follows:

Maximum permissible                    Minimum genetic                    Number of plants required

        offtypes                                      purity (%)                         per sample for observation

            0.10                                            99.9                                                4,000

            0.20                                            99.8                                                2,000

            0.30                                            99.7                                                1,350

            0.50                                            99.5                                                   800

            1.00 and above                            99.0 and above                                  400

V. Calculation, interpretation and reporting of the result

Percentage of other cultivars, other species or aberrant found may be calculated upto first place of decimal.

While interpreting the result, use of tolerance may be applied by using the reject Table given below at serial No. VII.

VI. Analyst for grow-out test 

The analyst employed for conducting “Grow-out-tests” should possess the basic qualifications as identified under Rule 20 of Seed Rules 1968.

VII. Reject number for prescribed standards and sample size

    Standard                                                                Reject numbers for sample sizes of

                                                                                            800                400

    99.5 (1 in 200)                                                                    8                    *

    99.0 (1 in 100)                                                                   16                    8

    95.0 (5 in 100)                                                                   48                   24

    90.0 (10 in 100)                                                                 88                   44

    85.0 (15 in 100)                                                                128                  64

* indicates that the sample size is too small for a valid test.