LESSER YAM (Dioscorea esculenta (Lour.) Burkill)

I. Application and Amplification of General Seed Certification Standards

The General Seed Certification Standards are basic and, together with the following specific standards constitute the standards for certification of lesser yam.

II. Land requirements

Land to be used for seed production of lesser yam shall be free of volunteer plants. Swampy and shaded conditions may be avoided.

III. Field Inspection

A minimum of three inspections shall be made, the first after about 90 days, the second after about 150 days and the third after about 200 days of planting or at appropriate growth stage depending on the crop duration of the variety concerned to verify offtypes and other relevant factors.

IV. Field Standards

A. General requirements

1. Isolation

Seed fields shall be isolated from the contaminants shown in the column 1 of the Table below by the distances specified in columns 2 and 3 of the said Table:

        Contaminants                                                                                   Minimum distance (meters)

                                                                                                                Foundation        Certified

            1                                                                                                         2                     3

Fields of other varieties                                                                                    5                     5

Fields of the same variety not conforming to 

varietal purity requirements for certification                                                       5                     5  

B. Specific requirements

        Factor                                                                                              Maximum permitted (%)*

                                                                                                                Foundation            Certified

      Offtypes                                                                                               0.050                    0.10

      Plants infested with scale insects                                                            None                    None

* Standards for offtypes  shall be met at the final inspection and for the designed insects at each inspection.

Note: 1. All offtypes and plants infested with scale insects shall be rogued out along with the tubers and     

             destroyed.

          2. Gaps in the seed field shall not be more than 10.0 %.

V. Seed standards

A. Specification for Foundation and Certified classes shall be as under:

1. Seed size (weight of the tuber):100-150gm.

2. In a seed lot, tubers not conforming to specific size shall not exceed more than 5.0%(by number).

3. The seed material shall be reasonably clean, healthy and shall conform to the characteristics of the variety. 

    The tubers not conforming to the varietal characteristics shall not exceed 0.050% and 0.10 (by number) 

    for Foundation and Certified seed classes respectively.

4. Cut, bruised, unshapy, cracked tubers or tubers damaged by insects (other than scale insects) slugs or 

    worms shall not exceed more than 1.0% (by weight).

5.  Maximum tolerance limit of tubers showing visible symptoms of infestation caused by scale insects will be      

     as follows:

        Factor                                                                                              Standards for each class

                                                                                                                Foundation            Certified

Tubers infested with scale insects                                                                None                       None