AFDC 30 (1917 ) DTZS  
 
      DRAFT TANZANIA STANDARD  
 
 
 
 
 
 
 
 
Sweet Orange  (Citrus sinensis L.) seed — Requirements for 
certification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                    TANZANIA BUREAU OF STANDARDS  
 AFDC 30 (1917 ) DTZS  
 
  
Sweet Orange  (Citrus sinensis L.) seed — Requirements for 
certification  
 
1. Scope  
This Tanzania standard specifies the certification requirements for pre -basic and certified seed of sweet 
orange  (Citrus sinensis  L.). 
It includes requirements for eligible varieties, application for certification,  field, field inspection, seed 
sampling, laboratory testing, certificates, packaging, labelling and post -control plot.  
 
2. Normative references  
The following documents are referred to in the text in such a way that some or all of their content 
constitutes requirements of this document. For da ted references, only the edition cited applies. For 
undated references, the latest edition of the referenced document s (including any amendments) applies.  
International Rules for Seed Testing Published by the International Seed Testing Association (ISTA)  
OECD Seed Schemes for Varietal Certification or the Control of Seed Moving in the International Trade   
OECD Seed Schemes; Guidelines for Control Plot Tests and Field Inspection of Seed Crops  
 
3. Terms and definitions  
For the purposes of this standard , the ter ms and definitions given in ISTA, OECD referenced documents 
and the following apply.  
3.1 
seed test certificate  
legal document issued by the national seed certification authority, which states that a seed lot has met the 
prescribed requirements set in this standard  
3.2 
distinctness  
variety is deemed to be distinct if it is clearly distinguishable in at least one character from any other 
variety whose existence is a matter of common knowledge at the time of filing the application for 
registration  
3.3 
field 
defined and identifiable area of land or facility that is used to produce a seed crop under the Seed 
Certification Scheme  AFDC 30 (1917 ) DTZS  
 
 3.4 
field inspection  
examination of a field and or seed crop, by an inspector to check if the prescribed requirements for seed 
certifica tion have been satisfied  
3.5 
field number  
number assigned to the field by the national seed certification authority, when the application form for 
certification is submitted  
3.7 
seed grower  
person or entity registered to produce seed  
3.8 
isolation  
prescrib ed distance or time between crops that is required to prevent contamination either mechanically 
or by cross pollination  
3.9 
inspector  
authorized or licenced official responsible for carrying out field examination for seed certification purposes  
3.10 
intern ational seed testing association (ISTA) rules  
instructions for seed testing that should be adhered to published by the International Seed Testing 
Association  
3.11 
label  
tag or other device that is attached to, written, stamped, or printed on any container of seed or that 
accompanies any lot of bulk seed and which describes the kind of seed and any other information 
required by relevant regulation  
3.12 
rotation  
planting a different crop on a particular piece of land in a prescribed  growing season that is req uired as a 
useful tool in preventing soil disease s, insect pests, weed problems and for building healthy soils.  
 
3.13 
maintainer  
person or organisation responsible for the production or maintenance of a bred variety included in a 
national list of varieties /variety catalogue eligible for certification, and ensure that the variety remains true 
to type throughout its full life -span  
3.14 
national seed certification authority  
national designated authority responsible for conducting seed certification processes  
3.15 
off-type 
plant of the same species which does not exhibit the recognised and accepted habit and characteristics of 
the variety being grown  AFDC 30 (1917 ) DTZS  
 
 3.16 
parental material  
population or lines used by a breeder to maintain a variety  
3.17 
pure seed  
species stated  by an applicant, or found to predominate in a test, and includes all botanical varieties and 
cultivars of that species, including intact seeds and pieces of seed units larger than one -half their original 
size 
3.18 
variety registration  
listing of an approv ed new variety in a national variety catalogue after it has been tested and satisfied the 
prescribed requirements for distinctness, uniformity, stability, and has value for cultivation and use  
3.19 
rogueing  
removal of off -types and diseased plants or any o ther unwanted plant from a seed crop if they may 
reduce the quality of the harvested crop  
3.20 
seed certification  
process by which the quality and identity of a seed lot is assured through official control and inspection by 
designated seed certification au thority  
3.21 
seed lot  
defined quantity of seed bearing the same reference number and for which the origin, production history 
and identity is known  
3.22 
stability  
condition where distinguishing characteristics of a variety remain unchanged after repeated g rowing 
cycles  
3.23 
uniformity  
condition of a variety, subject to the variation that may be expected from the particular features of its 
propagation, to remain sufficiently homogeneous in its relevant characteristics  
3.24 
variety  
assemblage of cultivated pl ants that is clearly distinguished from other plants by any characters 
(morphological, physiological, cytological, chemical, or others) and which retains its distinguishing 
characteristics when reproduced by the normal means for the crop  
3.25 
variety catal ogue  
list of varieties that have been registered by a national designated authority  
3.26 
carryover seed  
seed produced and certified in previous season and stored for one or more cropping seasons/ or past its 
valid test duration  AFDC 30 (1917 ) DTZS  
 
  
 
 
3.27 
seed dealer  
any regi stered person, firm, agency, cooperative engaged in the production, processing or marketing of 
seeds  
3.28 
seed  
planting materials used for generative propagation of plants  
3.29 
breeder seed  
nucleus seed from the breeder and is used to produce pre -basic see d 
3.30 
pre-basic seed  
 seed that is derived from breeder seed and shall be produced under the responsibility of the breeder or 
maintainer  through one cycle of multiplication  
3.31 
certified seed  
seed that is produced from pre-basic seed under the responsibi lity of a seed dealer other than the 
breeder or maintainer   
3.32 
scion 
a young shoot or twig of a plant especially used for vegetative propagation  
3.33 
bud 
a small growth at the tip or on the side of a plant stem that later develops into a new shoot  
3.34 
rootstock  
part of a plant  (base and root portion)  from which new above ground growth can be produced  through 
vegetative propagation ( grafting and budding)  
3.35 
clone 
plants that are able to propagate by asexual means to produce genetically identical plants.   
3.36 
budding  
a vegetative propagation technique in which a single bud from a desired plant is  used to generate a new 
plant of desired characteristics.  
 AFDC 30 (1917 ) DTZS  
 
  
 
 
4. General requirements  
Key parameters required to implement this standard are elaborated in the varie ty descriptors, field and 
laboratory requirements  
4.1 Eligible varieties  
4.1.1 Varieties eligible for seed certification shall be those registered in the variety catalogue.  
4.1.2 The national seed certification authority shall keep the official descriptor of the varieties in hard and 
electronic copies.  
4.2 Inspection and laboratory testing  
4.2.1 The minimum information for an application for certification of a seed crop shall include the 
following:  
a) name, address and contact details of the seed grower;  
b) crop and variety to be sown;  
c) physical location;  
d) area and reference number of the field, and its cropping history for the past two cropping 
seasons;  
e) class of seed to be produced; and  
f) registration number of the seed dealer . 
4.2.2 Information and records related t o the previous cropping history, origin of seed planted, and field 
inspections shall be kept and used for certification to ensure full traceability of quality, genetic identity and 
purity of the seed harvested.  
4.2.3 The inspection of seed crops shall be d one in accordance with OECD Seed Schemes; Guidelines 
for Control Plot Tests and Field Inspection of Seed Crops. If the field is found to be in conformity with the 
standards stated in Field requirements (Table 1) it is approved.  
4.2.4 The seed lot shall be sampled and tested in an official or authorized laboratory. The sampling and 
testing of seed lots  shall be done in accordance with the relevant procedures described in the ISTA rules.  
4.2.5 A seed lot  that conforms to the standards set out in laboratory re quirements (Table 2) shall be given 
a seed test certificate and a unique reference number to confirm its status under the certification scheme.  
 
 
 AFDC 30 (1917 ) DTZS  
 
 5. Seed classes  
For the purpose of this standard, the following classes of seed shall apply:  
a) Pre-basic seed; and 
 
 
b)  Certified seed  
 
 
6. Land Requirements  
Land to be used for clonal propagation of sweet orange shall be free from volunteer plants and soil borne 
disease .  
7. Field Requirements  
 
7.1.       Pre-basic seed/clones shall be produced under the responsibility of  the breeder or maintainer.   
7.2. Certified seeds shall be produced in one generation.  
7.3. The national certification authority shall inspect and certify the production of pre-basic  and 
certified seed crops.  
7.4.     A field producing sweet orange seedlin gs shall be approved for certification if it complies with the 
requirements in Table 1  
Table 1. Field requirement for certification  
 
S/N Variable  Pre-basic   certified  
i.  Rotation, season, min.  2  2 
ii.  Isolation, m, min.  2  2 
iii.  Pure living clones   
(%), min . 99  99 
iv.  Other living plants including 
Rootstocks (%), max.  1  1 
v.  Off-types per 1000 plants, max.  1  1 
vi.  No. of 
inspection, 
min Rootstock  1  1  
scion (at fruit 
maturity)  1   1 
grafted (before sale 
of clones or budded   1  1 
vii.  Plants infected with virus  0  0 
viii.  Plants infected with dieback, max, %  0  0.5 
ix.  Parasitic weed ( cuscuta campestris)  0  0 AFDC 30 (1917 ) DTZS  
 
  
7.5. Fields may be rejected for certification because of unsatisfactory condition caused by poor 
growth, poor stands, excessive disease presence, insect damage , and any other condition that 
prevents accurate inspection or creates doubt as to the identity of the variety.  
 
 
7.6.  Clone specifications  
a) The specification in respect of size of clones for pre-basic  and certified classes shall be as 
follows:  
b) The minimum diameter of the rootstock should be 0.6 cm 
c) The height of the budding  point should range from 25 -30 cm.  
d) The diameter of budding at 10 cm above the bud union should range from 0.6 – 1 cm  
e) The height of the plant should be 30-40 cm  
f) The budded  clone should be fr ee from suckers.  
g) In the clone lot, clones not conforming to specified size shall not exceed 5.0% (by number).  
 
 
8.  Seed sampling and laboratory standards  
 
8.1 The seed lings from the field approved for certification shall be kept as an identified unit until 
processing. After processing, sampling shall be done in accordance to ISTA rules and submitted to the 
laboratory for testing where a conformed sample shall be given a certificate with a unique lot number for 
the purpose of tracking.  
8.2 The maximum size of a clonal  lot for certification purposes is 100 000 plants;  lots larger than this shall 
be divided and given separate lot numbers.  
8.3 Laboratories authorized by the national seed certification authority to conduct seed testing for 
certification shall follo w the methodology established in the ISTA rules for sweet orange  seed.  
8.4 The seed lots shall comply with the laboratory requirements specified in Table 2.  
Table 2 — Laboratory requirements for certification  
S/No  Variable  Pre-basic   Certified  
i.  Diseases (%), max  
• Plants infected with viruses  0  0 
 
• Die back ( Phytophthora 
cinnamom i) (%)  0  0.5 
• Citrus  greening or Huanglong 
Bing (HLB)  0  0 
• Psorosis ( Citrus psorosis 
ophiovirus ) 0  0 
• Citrus tristeza  0  0 
 AFDC 30 (1917 ) DTZS  
 
 8.5. The laboratory test report shall be i ssued in accordance with Annex B  
 
 
 
 
9. Certificates  
9.1 The seed test certificate for a seed lot shall be signed and issued by the national seed certification 
authority and shall include all information presented in Annex C. This certificate shall be valid f or a period 
of five months.  
9.2 Carryover seeds shall be transferred into relatively larger polythene bags so that the roots will not 
exceed the size of the bag. Carryover seeds shall be re -examined and if it  complies with this condition, a 
new test certif icate shall be issued for the seed lot, which cancels the previously issued certificate, and 
shall include the certificate number of the cancelled certificate.  
 
 
10.   Packaging and labelling  
10.1 All classes of seed that have been certified shall be packaged in new containers which shall be 
marked with the company name and crop species and shall have the official label of the national seed 
certification authority.  
10.2 The labels for each class are identified by the following colours:  
➢ Pre-basic seed: Violet ba nd on white  
➢ Certified Seed Blue  
10.3  If budded clones are treated with any chemical harmful for human or animal, the container shall 
carry a label stating the chemical used and warning of the health risks using English and Swahili.  
10.4 The labels shall b e prominent, indelible, legible and fixed to the containers by an authorized person 
in such a way that they cannot be destroyed or easily removed. The following information shall be 
included on the official labels:  
• name of the crop, “sweet orange  seed”;  
• species (Latin name);  
• variety denomination;  
• seed lot number;  
• test certificate number;  
• date of test;  
• net weight;  
• clone  treatment declaration (if applicable)  AFDC 30 (1917 ) DTZS  
 
 • logo of the national certification authority;  
• name and address of certifying authority;  
• seed class;  
• year and country of production; and  
• statement of re -packing and re -labelling (if applicable).  
 
 
10.5 Repackaging and relabelling are authorized in the following cases:  
a) the national seed certification authority may authorize the re -packaging and re -labelling of a 
particular seed lot that is produced in another country, but shall retain the original label 
information of the producing country; and  
b) where screen house or reusable polysheet is used treatment is compulsory in all seed Class  
c) where new polysheet is us ed no rotation or treatment is applicable in all seed Class  
 
 AFDC 30 (1917 ) DTZS  
 
 Annex  A 
(normative)  
 
Field inspection report  
Reference number..................  
Date of the report....................  
 
Seed grower information  
Name ……………………………………. Address ………………………………………  
Telep hone: ……………………………… E -mail.............…………………………………  
Registration number……………………. Number of inspections ....................................  
Field location  
Province/Region.............................................. District ............................... Sector .......………….…….........  
Latitude................................................................. Longitude ………………. Field number..................... .........  
Field size (Ha/acre) ………………………......... Cropping season ………. Crop species ……………........... . 
Seed class ………………………….…………… Variety ………………… Rotation ………………  
Variable  Observations/results  Comments/remarks  
Isolation, m    
Off types    
Deliberative disease  
    
   
   
   
   
General conditions of the crop (for example, 
drought, crop husbandry, etc.)   
 
Decision  
Decision on the approval  Justification  
The seed crop is approved for 
certification   
The seed crop is not 
approved for certification   
 
 
Name of seed grower                                                          Name of Inspector         
 
 
Date &signature                                                           Date, signature & stamp                 AFDC 30 (1917 ) DTZS  
 
 Annex  B 
(informative)  
 
Seed laboratory test report  
Name of seed grower  
Species, variet y, class,  
Testing and Issuing laboratory  
Sampled by  
Test number  
Country of origin  
Label serial number  
Seed Lot Reference Number:  
 
Number of 
containers  Date of sampling  Date sample 
received  Date test(s)  
concluded  
 Test number  
 
     
ANALYSIS RESUL TS 
Deliberative disease  
 
  
Other determinations  
 
Decision on the 
approval  Justification  
The seed crop is 
approved for certification   
The seed crop is not 
approved for certification   
Place  
 Date  
 Name & Signature  
 
 AFDC 30 (1917 ) DTZS  
 
 Annex C  
(Normative)  
 
Seed test cer tificate  
This certificate is issued for a seed lot which has satisfied all the requirements of the certification scheme  
  
Previously issued certificate 
number..............  Certificate No. ………….  Standard: .................  
APPLICANT INFORMATION  
Seed Lot  Reference  
Number  
 Species and  
Variety  
 Class 
 number of a lot  Number of  
containers  
     
Name of testing laboratory:  Test number:  
ANALYSIS RESULTS  
 Deliberative disease  
  
Other determinations  Statement of packaging and re -
labelling: (if  
applicable)  
 
 
National Seed Certification Authority  
Signature ………………………………………………………………….  
Place and Date ………………………………………………………………….