Handling and analyzing
There are several aspects to this part of procurement, many of which are critical to maintaining the quality of the reproductive material that has been obtained. It covers such activities as reception of material at the centre of operations, processing, testing, storage, treatment, distribution, and documentation. Some key points to consider are listed below.
Reception and registrationIt will be important to keep adequate records of seed lots etc. that are received by any program using forest reproductive material. This applies equally well to commercial plantation programs as to agroforestry projects with farmers. Information required will include details of source, initial quality and quantity, processing, treatment or other activities, results of analysis tests while under storage, the storage regime, and records of distribution (quantities and recipients). There are plenty of examples of the types of forms required to ensure that this information is recorded and kept in the register of seed lots. Software has been produced to help computerise this process when this is appropriate. SeeFinding out more - Selected references - Generalfor general guidelines. SeeFinding out more - Information systemsfor examples of seed information management systems.
ProcessingWhere collections are made locally, seed will need to be extracted from a variety of fruit types that are usually either fleshy or dry, and then cleaned to an acceptable level. This must be done carefully to maintain the physical and physiological quality of the seed. There are a wide range of techniques that have been developed to do this job, and different types of small-scale machinery have been designed to help. Often simple manual methods will be adequate. SeeFinding out more - Selected references - Generalfor general guidelines.
StorageForest reproductive material will invariably have to be stored until required. This may be short-term (weeks to a year) or long-term (many years to decades) depending on the purpose to which the material will be put (e.g. stocks for plantation programmes, or long term gene conservation). Tree seed crops are often erratic, and harvesting needs to be maximised in good seed years. Seeds can be classified into two basic types with regard to storability, related to the environmental conditions of the species' natural habitat. Orthodox seeds store best when dried and kept cool. Recalcitrant seeds need to be kept moist and may not withstand cooling for storage. Current research indicates that there are also a wide variety of intermediate types. Because of the practical importance of seed storage, there is a lot of information available about techniques, and there is considerable on-going research to improve the storability of the more recalcitrant seeds. The use of ultra-low temperatures for storage (cryostorage) is being developed for specialised reproductive material. It is important to choose appropriate technology for seed storage. Simple systems are often adequate, especially for community forestry activities. Air-conditioned seed stores should be introduced only where they can be operated and maintained properly - if they are to be of value. They will be essential for gene conservation. SeeFinding out more - Selected references - Storagefor further information.
Seed analysisA knowledge of the physical, physiological, and phytosanitary quality of seed is important to monitor collection, processing, storage, distribution and decide on techniques of propagation in the nursery. All programmes should have some facilities for testing these qualities. Seed laboratories (along with storage facilities) form the core of the many new dedicated seed centres that are being established nationally. Tests are carried out on samples taken from seed lots, for which there are a variety of sampling procedures and equipment. The main characteristics tested for are usually: seed weight (seeds per kilogram), purity, moisture content, germination percentage and vigour. Testing will require a range of equipment which need be only very basic to be appropriate. However, precision equipment such as balances and incubators will often be needed. As with storage, incubators should be used if they can be properly operated and maintained. Many new techniques are being developed to measure such characteristics as embryo development, vigour, etc. A range of rules and regulations are available which build on experience with agricultural seed, and can be used for certifying seed quality. The International Seed Testing Association (ISTA) is one of the best sources for information on seed analysis. SeeFinding out more - Selected references - Analysisfor further information on techniques. SeeFinding out more - Organizations - ISTAfor their information.
TreatmentSeeds may need to be treated in a variety of ways to improve storage, germination or survival in the nursery or field. This can involve dusting with fungicide or insecticide prior to field storage, coating with repellant for direct sowing, or subjecting the seed to various techniques that help break physiological or physical dormancy (such techniques vary from subjecting the seed to special regimes of cold and moisture, to physical breakage of impermeable seed coats). Some species may require inoculation with microsymbionts for healthy growth of the seedling. SeePropagation in nurseriesfor notes about nursery techniques.
DistributionThe process of distributing seeds to users should be done with care, providing proper records. This is important to be able to follow up on the success or failure of plantations. SeeFinding out more - Selected references - Generalfor recommended texts that cover all aspects of seed handling.
last updated: Wednesday, April 18, 2007