Seed management is vital for the performance of the trees that will grow from that seed. It starts with how mother trees (or seed sources) are identified, selected, and managed, and proceeds to when the seeds are collected, processed, tested, stored, and finally despatched and used to grow into a tree. Therefore, seed management takes into consideration the seed sources and the processes for handling the seeds.
Instruction 15: Tree seed shall be collected from sources approved by NTSC, under the following categories:
(i) Seed collection zone – an area with fairly uniform ecological conditions, on which are found stands showing similar phenotypic or genetic characteristics. Seed collection zones are largely farmland seed sources, and may include small plantations, woodlots, boundary plantings, shelter belts or identified stands. For example, a seed collection zone for Albizia coriaria (Mugavu) and Milicia excelsa (Mvule) would be located in natural forests, woodlands or farmlands where adaptation to the local environment is easier to ascertain.
(ii) Identified seed source – a collection of trees or stand with superior characteristics identified in either natural or plantation forests, located within a single area with fairly uniform ecological conditions. Little or no phenotypic selection has taken place . Such stands are occasionally selectively thinned or managed for purposes of improving the quality of seed produced from a stand.
(iii) Selected seed source – This consists of a stand of superior trees, selected because of their important traits, e.g. stem form or growth habit. Seed stands may be selected in the natural forest or plantations.
(iv) Qualified seed source (also called tree seed orchards) – Seed orchards are individual trees or stands planted for specific purposes of producing seed for use in planting activities. They usually consist of families with outstanding genetic quality and are planted at regular spacing and specific design. They are usually established from a minimum of 30 families of trees. The more the number of families included, the broader the genetic base of the seed produced.
Instruction 16: NTSC shall register and operate as a plant breeder with the Seed Certification Service for purposes of producing, importing and supplying quality tree seed, in accordance with the Seed Act (2006) and National Forestry and Tree Planting Regulations (2016).
Instruction 17: All sources of imported seed shall be approved by NTSC, in consultation with stakeholders in the seed industry to ensure that such seed sources are suited to the Ugandan conditions and have a proven quality standard of performance. The imported seed shall be accompanied by a Certificate of Origin
Instruction 18: Relevant phyto-sanitary certificates shall be sought from the country of seed origin, to be used for clearance and obtaining a Seed Import License from the Ministry of Agriculture, Animal Industry and Fisheries.
Instruction 19: The private farmers should work with NTSC in establishing and managing trees on-farm for purposes of producing quality seed, and NTSC should provide technical guidance and hands-on training for this purpose. This will make such farmers legible to sell their seed to NTSC.
Out of eight bio-geographical zones on the African continent, five of them are represented in Uganda, which makes the country an international biodiversity hotspot. Accordingly, Uganda has a number of regionally endemic and rare animal and plant species and landraces that must be preserved.
The National Biodiversity Strategy and Action Plan (2015-2025) indicates that Genetically Modified Organisms could have a detrimental effect on biodiversity by cross-pollinating with indigenous species, or by being viable in areas that non-genetically modified crops are not, thus resulting in additional loss of the natural habitat[1]. Under Criterion 10.4 of the NFSS, Genetically Modified Organisms are prohibited in forest management and conservation.
Instruction 20: Genetically Modified Organisms shall not be used in afforestation and reforestation activities.
Components of good seed quality include (Mbora A, et al, 2009 [2] ):
(i) The seed is collected from a site with conditions similar to those at the site where it is going to be planted e.g. similar temperature, rainfall, altitude and same soil characteristics
(ii) Collected from high quality mother trees for the purpose for which the seed is going to be planted: healthy, big crowns, uniform size, uniformity in flowering and seeding, good form, high branches and well-spaced
(iii) Seed is collected from many trees of the same species, allowing for cross pollination. The tree populations could be in line, a group or scattered
(iv) Seed is collected from mother trees which are surrounded by other good quality trees
(v) Seed with superior inherited traits for good growth performance, good health and shape, with the desired end products such as timber, fruit fodder
(vi) Seed collected from a number of unrelated mother trees (normally >30 trees). Small but equal amounts of seed from each mother tree. Collected from adjacent farms and bulked.
(vii) Seed harvested when optimally mature. Example is brown pods of Calliandra calothyrsus. Seed collectors need to know the visible signs of seed maturity for different species
(viii) Quality seed can be stored for a relatively long time under good storage conditions e.g. when stored in good containers.
(ix) Seed collected when mature germinates well and produces healthy seedlings, which under optimum conditions, will grow fast into good trees. The trees should be able to produce desired goods and services e.g. good fodder, tasty fruit, good timber or good paper.
Instruction 21: Seed with high moisture content and sensitive to drying (recalcitrant) should be sown immediately after harvest. Some recalcitrant seed may be temporarily stored in moist sawdust at room temperature. Guidance should be sought from the NTSC on species-specific information on seed storage
Instruction 22: Guidelines for Control of Tree Seed Quality issued by NTSC shall be used by FMIs during seed collection, processing, testing, packaging, storage and distribution. In particular, timber species require high genetic and physiological quality control and, therefore, should be collected by trained seed collectors under close monitoring and supervision.
Instruction 23: Seed shall be collected only from seed sources which have been approved and registered by NTSC, while observing the following quality standards:
(i) Collect seed only from vigorous trees of reasonably good form, good growth, or other desired characteristics. Avoid collecting seed from stands containing numerous poorly formed, abnormal or diseased trees.
(ii) Collect seed from mature or nearly mature trees. Over-mature trees may produce seed with low viability.
(iii) Do not collect seed from isolated trees of naturally cross-pollinating species. They are likely to self-pollinate, the seeds are likely to be few, of low viability and the seedlings produced from such seeds are likely to be weak and malformed.
(iv) For seed collected from “identified sources”, collect seed from at least 30 parent trees that are at least 100 metres apart. Using a large number of seed sources increases the gene pool or genetic diversity of the seed and seedlings.
Seed documentation is a tool that ensures a proper record of the entire seed production system, including the technical documentation, such as seed sources, the seed phenology, seed collection, testing, storage and despatch. It also includes management documentation that provides records to support effective seed management and information sharing, e.g. cost of operations, research records, publications and list of seed sources. Therefore, seed documentation provides a comprehensive system of records of all phases of seed operations.
Instruction 24: The seed documentation system used at NTSC shall be reviewed and published to promote application
Instruction 25: NTSC shall maintain a National Register of all seed sources in which each unit of approved seed source is recorded. The National Register will contain full details of each unit including management, site and administrative details shown in the example in Annex 3. NTSC shall document activities related to these seed sources.
Instruction 26: All seed received by NTSC or other entity, whether local or imported, shall be well documented to provide identification of the seed and assigned a Batch Number that provides a unique identification of the seed. The Seed Batch numbers shall be quoted in all seed records, nurseries, forest management plan (FMP) records and research records.
Instruction 27: Appropriate forms shall be used to document the various technical and management records. These include, but are not limited to: Seed Source Data Form; Seed Collection and Handling Records; Seed Procurement Accounting Form; Seed Storage Information Form; Seed Sampling Form; Seed Test Forms; Seed Storage Form and Seed Despatch Form.
NTSC is responsible for seed testing, covering various physical and physiological tests. Among the physical tests are seed purity, seed health, seed count. The physiological tests includes moisture content, germination percentage test and germination vigour test.
Since 1992, NTSC has amassed experiences and documented species-specific guidance on seed storage, and therefore, it is a good position to offer technical advice on the right conditions for the storage and the right storage materials of any given seed
Instruction 28: NTSC shall keep an updated tree seed testing and storage protocol based on the International Seed Testing Association (ISTA) Protocol [3]: . The protocol may be included in the Guidelines for Quality Control of Tree Seed
Instruction 29: The tree seed laboratory at NTSC shall be listed with the Ministry of Agriculture, Animal Industry and Fisheries as a National Tree Seed Laboratory for purposes of testing and issuing certificates for tree seed, in accordance with the Seed Act (2006).
Seed storage is the preservation of the seed under controlled conditions to prolong their viability. Since 1992, NTSC has amassed experiences and documented species-specific guidance on seed handling, and therefore, it is in a good position to offer technical advice on the right conditions for storage and the right storage materials for any given seed.
Instruction 30: Depending on the type of species, the seed shall be stored under specific conditions, including cool, aerated condition, ambient/room temperature storage (25oC) and cold storage/cold room with average temperature of 5oC – 8oC, to maintain viability.
Instruction 31: All seed distributed by NTSC shall be packaged and branded with a label tag that provides specific information, including the Batch Number, seed source, date of seed collection, seed viability and germination percentage. Depending on the seed source, the colour of the label may be: Yellow (for category Source Identified); Green (for category Selected); and Pink (for category Qualified).
The process of seed handling begins from seed collection up to seed despatch, aimed at ensuring good quality seed both physiologically and genetically.
Instruction 32: Until a Guideline for Tree Seed Quality Control is developed, FPs should seek technical advice from NTSC on how the seeds for different species can be handled at various levels along the seed production chain in the nursery for best germination and performance. The technical advice should cover, among other things:
(i) Seed handling at collection - shall aim at obtaining high quality seeds, based on the following principles:
• Collect seed when trees are at the peak of seed production. The first fruits produced are often not fully mature and may contain poor quality seeds.
• Collect during good seed years, except for endemic or rescue mission, as poor seed years produce inferior and little seed
• In natural forest, ensure regular distribution of seed trees by keeping a distance of 50-100m from each other, to ensure that trees are genetically diverse, hence not closely related. Avoid collecting seeds from related trees.
• On farmland it is better to collect seed from trees of the same species from 4-10 farmers having land adjacent or same ecological zone.
• Collect seed from at least 30 healthy mother trees to collect enough genetic variation and avoid isolated trees.
• Collect equal amounts from each tree to ensure that the genetic information of each seed tree is equally represented.
(ii) Seed handling during extraction and processing –
• Collected seed should be extracted from fruit as soon as possible. Depending on species, dry or wet method may be used, e.g for many legumes, pods can be dried in the sun for two days and then rubbed across a coarse wire mesh through which seed falls. The extraction method used should not damage seed to cause significant loss in viability.
• During extraction, impurities such as soils, chaff, diseased or partly eaten seed, and insects should be removed by winnowing or hand –sorting.
• After extraction, most seed should be dried further before storage. The lower the moisture content of the seed, the longer it can be stored. Normally seed with moisture content of 10% and below will maintain high viability for several years if stored correctly. Sun dry small and medium sized Orthodox seeds for two or three days to reduce moisture to an acceptable safe storage level. Large sized orthodox seed species require more days of sun drying to attain safe storage moisture content.
• During processing, the viability and purity of seed should be tested. Viability is the percentage of seed with potential to germinate given necessary conditions for the germination. Viability therefore provides a reference level of germination for users. Purity is the percentage by weight of pure seed in a sample and is estimated by weighing a sample of seed before and after the removal of impurities. Particular impurities such as contaminating seed are recorded.
• Seed shall be properly labelled during processing and storage. An unidentified seed lot is almost worthless. As a minimum, seed should be labelled with the species name, original collection source, collection date, producer, viability and purity.
(iii) Seed handling during temporary storage – whether there is need for refrigeration, ambient conditions or aerated storage. Appropriate storage of seed in the interval before planting will maintain its viability and physiological quality. Orthodox seed [4]: , which can be stored without losing viability for a long time, should be kept cool, dry and dark in airtight containers (such as plastic or glass bottles with screw-tight lids. If possible, orthodox seed should be stored in a refrigerator.
For recalcitrant seed [5]: , storage is more problematic. Seed is viable for only a short time and, whenever possible, should be planted out immediately. If this is not possible, storage at 10 to 15ºC in humid conditions, for example in moist sawdust, may extend longevity.
(iv) Seed handling at despatch - Particular care shall be taken to ensure that seeds have proper documentation about the species, when it was collected, where it was collected, and it physiological quality status. The seed shall be packed properly and well protected from adverse condition; it should be kept in polythene bags for protection against rains and well protected against rough handling.
(v) Seed handling in-transit – the handler shall be mindful about the acclimatisation of the storage conditions to ensure that seed viability is maintained. While transporting the seed, ensure optimal ventilation especially for orthodox seed; protect seed from moisture and avoid seed desiccation, particularly for recalcitrant seeds.
(vi) Seed handling at the nursery - the seed should be put in a nursery store on delivery. Avoid exposing the seed to the sun. The seed may then undergo the following processes:
• Pre-sowing treatment required - different seeds may require undergoing specific treatment before sowing to break their dormancy and promote germination. This may include soaking in water overnight, or warm water for a few hours, etc. NTSC has compiled notes on pre-sowing treatment for different tree species, which can be provided on request. Annex 4 presents pre-treatment methods for seed of some species.
• Sowing method – including sowing in seed beds, or direct sowing in pots and the correct sowing density depending on viability, the size of the seed. For example, eucalyptus, pine, etc are small-size (do it in seedbed) - The sowing density will also depend on the size of the seeds.
NEMA(2016), National Biodiversity Strategy and Action Plan II (2015-2025) ↩︎
Mbora A., Schmidt L., Angaine P., Meso M., Omondi W., Ahenda J., Lillesø. J-P.B, Mwanzia J.M., Mutua N. A., Mutua Wangu R.., Jamnadass R. 2009. Tree seed quality guide. World Agroforestry Centre, Nairobi, Kenya. 28pp. ISBN: 978-92-9059-272-3 ↩︎
https://www.seedtest.org/en/international-rules-_content---1--1083.html ↩︎
Seeds which will survive drying and/or freezing during ex-situ conservation ↩︎
Seeds that do not survive drying and freezing during ex-situ conservation. By and large, these seeds cannot resist the effects of drying or temperatures less than 10 °C (50 °F); thus, they cannot be stored for long periods like orthodox seeds because they can lose their viability ↩︎