Decision No. 20/2000/QĐ-BNNPTNT/KHCN on issuing industry standards

DECISION

Regarding the issuance of industry standards

THE MINISTER OF AGRICULTURE AND RURAL DEVELOPMENT

Pursuant to the Quality of Goods Ordinance issued on December 27, 1990 by the State Council;

Pursuant to Decree No. 73/CP dated November 1, 1995 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Agriculture and Rural Development

Considering the proposal of the Director of the Science and Technology Department - Quality Assurance

Pursuant to …;

Article 1 : Now promulgates standard 10 TCN 404-2000 "Method for conducting post control plots"

Article 2 : This Decision shall take effect 15 days from the date of signature

Article 3: The Heads of the Office, Directors of the Science and Technology Department - Quality Assurance, Central Seed Testing and Certification Center, and related units shall be responsible for implementing this decision.

STANDARDS

Method for conducting post control plots
( Method for conducting post control plots )

10TCN 404 - 2000

(Annexed to Decision No. 20/2000/QĐ-BNN-KHCN

dated March 6, 2000)

Article 1. Scope of Application:

This standard specifies the principles and methods for evaluating the genetic purity, uniformity, and other quality criteria of a seed lot through field trials.

This standard applies to seed lots of food crops, industrial crops with short growth cycles that are being produced and traded throughout the country, when requested by management agencies, individuals, organizations engaged in production and trade, or users of crop seeds.

2. Purpose of post-control:

Post-control of crop seeds aims to determine:

- The genetic identity and purity of the seed lot as a basis for using the seed lot or resolving doubts and disputes related to the quality of the seed lot.

- In the case of hybrid seeds, post-control also evaluates additional criteria such as male sterility of the female parent line and the yield of F1 from the same cross but maintained under different conditions.

3. Terms:

In this standard, the following terms are understood as follows:

3.1. Post-Control Plots - Post Control Plots - abbreviated as Post-Control:

It refers to the evaluation of the quality (mainly genetic identity and purity) of a seed lot through field testing of plants grown from seeds of the same lot. Post-control is conducted after seed plot testing and laboratory testing.

3.2. Genetic Identity (authenticity of the variety) - Varietal Trueness:

A seed lot is considered genetically identical if plants grown from seeds of the same lot consistently exhibit characteristic traits consistent with the standard sample or variety description during their growth and development.

3.3. Genetic Purity - Varietal Purity:

It is the degree of uniformity regarding characteristic traits of plants grown from seeds of the same lot. Genetic purity is calculated as the percentage of plants of the same variety compared to the total number of plants tested.

3.4. Off-Type Plant:

Plants that have one or more characteristics different from those of the variety being tested.

3.5. Variety Description Table - Table of Variety Characteristics:

A list of characteristic traits of a variety used to describe the variety and distinguish it from other varieties.

3.6. Standard Sample:

Seeds or plants grown from seeds that have characteristic traits consistent with the variety description, provided by the original breeder or obtained from the breeder's variety and recognized by authorized agencies.

4. Principles of post-control:

4.1. To test genetic identity, post-control experiments must be designed to compare representative samples of the seed lots participating in post-control with the standard sample of the variety.

4.2. To assess genetic purity, post-control experiments must be arranged and carried out to ensure that the information obtained is completely accurate.

5. Requirements:

5.1. Each post-control experiment only tests seed samples of the same variety. Different varieties will be tested in separate post-control experiments.

5.2. Post-control experiments can be conducted before, simultaneously, or after the use of the seed lot. The timing of post-control depends on the purpose of the experiment or the requirements of organizations, individuals with interests or responsibilities related to the seed lot.

5.3. The post-control field must be uniform, weed-free, and absolutely free of residual plants of the same species from previous seasons. During the entire post-control period, no weeding or use of herbicides or plant growth regulators is allowed.

5.4. The control in post-control experiments is the standard sample of the same variety. If the seed lot participates in post-control at a certain level, the standard sample should be at that level. Large quantities of standard samples can be collected and stored for use over multiple seasons. If the old standard sample quantity is nearly depleted, new standard samples must be prepared to replace them. The quality of new standard samples must be verified through comparative field trials and variety descriptions with old standard samples.

For imported seeds from abroad, the agency conducting post-control may consult the quality management agencies of the exporting countries to find suitable standard samples or descriptions of characteristic traits of the variety.

6. Methods of implementation:

6.1. Arrangement of post-control experiments:

- Randomized block design without replication. Blocks are rectangular plots where representative seeds of the seed lot participating in post-control are planted. Blocks are separated by appropriate paths for each type of crop.

- The area of each block ensures planting enough plants for testing, depending on the type of crop and the field purity standard specified for that crop. The number of plants in a block is calculated according to the formula:

Where:

- S (%) is the field purity standard.

- N is the optimal number of plants to be tested in one block.

If practical conditions do not allow, in some cases, the minimum number of plants to be tested from a seed lot must be at least n = 1/4 N (See Appendix 1).

6.2. Technical measures:

- Only one plant or one seedling is planted per hole.

- When transplanting plants from nurseries or seedbeds to the experimental field, they must be randomly selected and transplanted in patches, without selecting plants.

||| Other technical measures shall be implemented in accordance with the established seed testing regulations.

6.3. Inspection and evaluation of results:

6.3.1. Periods and number of inspections:

||| Inspections shall be conducted regularly throughout the growth and development period of the plant. Focus on the following periods:

||| - Seedling stage.

||| - Pre-flowering stage.

||| - Flowering and pollination stage.

||| - Grain formation stage.

||| Depending on the type of plant, the number of inspections during each period may vary from once to multiple times. Special attention should be given to distinctive traits that only appear for a short period.

6.3.2. Evaluation of variety correctness:

||| Compare the plants of the inspected seed samples with the standard sample and the trait description table of the variety. If most plants of the inspected seed sample exhibit characteristics consistent with the standard sample or the trait description table, then the inspected seed sample ensures variety correctness, and vice versa.

6.3.3. Evaluation of variety purity:

||| Observe, identify, count, and record the number of different types of plants within each plot. Different types of plants must be marked or possibly uprooted if accurately identified. Statistics will be compiled through repeated inspections and the result calculated using the following formula:

||| Total number of inspected plants - Number of different types of plants

||| P(%) = ------------------------------------------------------------------- x 100

||| Total number of inspected plants

||| P(%) is rounded to two decimal places.

||| Compare the results with the standards and conclude on the purity of the seed lot.

6.3.4. Evaluation of other criteria:

||| - For domestic-produced F1 hybrid rice lots from the same cross combination, additional comparisons regarding actual yield with the standard sample are necessary to fully assess the quality of the seed lot. Therefore, post-inspection trials for these lots must be conducted three times.

||| - When conducting post-inspection for male-sterile rice lines maintained domestically or imported for producing F1 hybrid rice, it is necessary to check the male sterility of these lines. Any self-pollinated plants (either entirely or partially) are considered different types of plants when calculating the purity of the male-sterile rice line according to the specified standards (See Appendix 2).

7. Announcement of Post-Inspection Results:

||| The agency conducting the post-inspection must provide conclusions on the post-inspection results and notify relevant quality management agencies, organizations, and individuals with interests related to the seed lot within thirty days after the completion of the post-inspection trial (See Appendix 3).

||| - File at the Ministry's Office

 Place of Receipt:
- As Article 3
||| - File at the Science and Technology Department - Variety Protection Division / MINISTER
||| REQUIREMENTS FOR FIELD PURITY AND NUMBER OF PLANTS TO BE INSPECTED IN POST-INSPECTION TRIALS

ANNEX 1:

||| Type of crop

2. Correctness inspection: Follow the general method.

3. Purity inspection of the variety:

3.1. Inspection of different types of plants: Follow the general method. Plants definitely identified as different types can be uprooted. Those still in doubt need to be marked and bagged separately for continued observation (if the plant has pollen-shedding capability). Count and compile the total number of different types of plants discovered.

3.2. Male sterility inspection: Only inspect the male sterility of plants considered correct varieties after checking and removing different types of plants (self-pollinated plants + different varieties).

There are three methods to inspect male-sterile rice plants and determine the male sterility of male-sterile rice lines:

3.2.1. Visual inspection:

||| Observe the entire plot based on the morphological characteristics of the plants when they spike. Individuals with stunted spikes, white or creamy-white anthers, pointed anther tips, and no pollen falling when shaken lightly are male-sterile plants. Conversely, those with normal spiking, round and yellow anthers, and pollen falling when shaken lightly are fertile or partially male-sterile plants.

Calculate the percentage of fertile and partially male-sterile plants out of the total number of inspected plants.

3.2.2. Bagging isolation inspection:

||| When the flower buds emerge, randomly select 30 consecutive plots, choose 1-2 flowers from each plot, and isolate them with paper bags to prevent external pollen from entering. After 10-15 days, open the bags and observe the number of full grains to determine the male sterility of the inspected plant.

Based on the observation of 30 isolated plots, calculate:

||| - Percentage of fertile individuals.

||| - Percentage of fertile grains (full grains) out of the total number of inspected grains.

3.2.3. Microscopic inspection:

||| On newly spiked flowers of representative plants (10 plants per plot), randomly take 5 flowers from the top, middle, and bottom sections, remove the anthers onto a slide, add 1-2 drops of 1% KI solution, use forceps to tear the anthers to release the pollen, discard the anther casings, place the pollen on the slide for examination. Normal pollen grains, when stained, appear dark green, round, and uniform in size. Abnormal pollen grains, which do not stain or only lightly stain, are sterile.

Depending on specific conditions and types of sterility, visual inspection combined with bagging isolation or microscopic inspection methods can be applied.

3.3. Evaluation of male-sterile rice line purity:

3.2.3. Microscopic examination:

 On newly emerged rice panicles of representative sample plants (10 plants per plot), randomly select 5 flowers from the beginning, 5 flowers from the middle, and 5 flowers from the end of the panicle, remove the anther sacs of these flowers and place them on a slide, add 1-2 drops of 1% KI solution, use forceps to tear open the anther sacs to allow pollen grains to escape, remove the outer layer, and place it on the slide for observation. Normal pollen grains, when stained, will appear dark green, round, and uniform in size, whereas abnormal pollen grains will have irregular shapes, fail to stain, or only lightly stain, indicating sterile pollen.

 Depending on specific conditions and types of sterility, the visual inspection method can be combined with the isolation bag testing method or microscopic examination.

3.3. Evaluation of the purity of male-sterile rice lines:

Hermaphroditic and sterile plants are not entirely considered as different types of plants. The purity of the male sterile rice variety line is calculated as follows:

Purity (%) = 100% - ( Proportion (%) of different types of plants + Proportion (%) of hermaphroditic plants + Proportion (%) of incomplete sterile plants ).

 Compare with the standard in Appendix 1 to determine whether the seed lot meets the criteria or not.

 

ANNEX 3:

SAMPLE REPORT OF POST-INSPECTION RESULTS

1. Variety Name : Seed Grade :

2. Season : Year :

3. Post-inspection Location :

4. Total number of seed samples participating in post-inspection :

5. Experimental plot area : Number of plants / plot:

6. Sowing date : Date of 10% flowering (Start):

 Date of maturity : Date of 80% flowering (End):

7. Isolation method :

8. Experimental field :

 - Soil type :

 - Previous crop :

9. Summary of weather and climate impact on the post-inspection field :

10. Summary of major pest and disease impacts and their effects :

11. Post-inspection data :

LN3

 Average

Note :

 - Specify the specific characteristics of differently typed plants.