Tips you can adopt to get better yields from your tree farm 

Just like how farmers growing various variety of crops are sensitised on how to access quality seed for improved yield, the same applies to farmers investing in growing various tree species.

This calls for farmers growing tree species to have knowledge in tree seed processing and production to avoid failure of tree germination.

Farmers in East Africa including those in Uganda dealing in tree-growing are privileged to follow tree seed processing guide provided in Agroforestry Tree Seed training hand book for community facilitators.

The handbook is prepared by Agroforestry experts from a Swedish development organisation called Vi Agroforestry fighting poverty and climate change through tree planting amongst farmers and farmer organisations in the Lake Victoria Basin in East Africa.

The purpose of the handbook is to guide community facilitators when training farmers on identifying and establishing good tree seed sources, how farmers can collect tree seed, process them, treat, store and distribute tree seed to earn income collect.

Once farmers acquire this knowledge and adopt good practices in treed seed processing, this will contribute towards sustainable tree seed systems and as a result improve and optimize productivity of agroforestry systems, environment and improve livelihoods of small-holder farmers in East Africa.

Seeds of Gold perused through the booklet and the details of the guide are outlined as below.

Tree seed sources
In the guide, the experts define tree seed source as a place where seed is collected. There are two major ways of obtaining seed; and this is by farmers collecting their own seed or procuring seed from formal institutions such as national tree seed centres.

This may be an identified or established number of trees in a landscape; farmland, natural forest or a group of trees from which farmers can obtain seeds.

The best seed sources for particular tree species should be in a suitable agro ecological zone for good seed production.

Farmers are expected to choose seed sources from areas which share the same climatic conditions in terms of average annual rainfall and altitude as one where the seed collected will be planted.

This ensures that trees will be well adapted to that environment. Seed trees from lowlands fit well in lowlands areas, while seeds from highlands fit well in highlands farms.

Farmers are expected to choose sources with trees which have desirable traits such as fast growth, pest resistance, healthy and quality products.

Use seed sources that have more than 30 trees to ensure good inherited genetic quality, as trees grow to be like their mother trees.

Avoid identifying isolated mother trees since they may end up self-pollination leading to having seeds which are not viable for germination.

In case of natural forest, farmers are expected to select mother trees of same species which are spaced 50-100m from each other.

For exotic tree species, ensure that trees of same species are spaced at least 10-14 metres from each other. This prevents pollination between closely related individual trees and allows good crown development.

Categories of seed sources
Farmland seed source: These are collected from trees on-farm owned by a farmer or farer organisation

This can be in urban areas where trees are planted by the roadside on roadside and indigenous trees retained for provision of services and other end-products such as fodder, timber apart from providing seed. Natural forest seed source normally identified in natural forests that are selected and managed for seed provision.

Plantation seed source which are usually superior tree stands planted in blocks of minimum one hectare. They primarily provide services or products but are also selected for seed provision due to the tree superiority.

A case in point is where some stands have been selected by national institutions to provide seeds of pine and cypress. Seed orchard source where trees are planted from high quality seed or grafted plant material.

They are specifically planted for seed or scion production, such as mango trees, oranges, avocado among others.

Farmers can collect the seeds using tools such as hooks, ladders, ropes, baskets, buckets, bags, crates, plastic sheets, netting sheet, which should be labelled and put in seed containers.

How farmers can tell when the seeds are mature
Different tree species flower at different times therefore it is important to carry out a flower and seed survey to assess maturity of the seed and to know the best harvesting time. The recommendations are that harvest when at least 30 trees have fruits or pods which are ready.

A mature fruit or pod can be confirmed by checking the size, colour and vigour of the fruit. The seed must appear whole and firm inside and this is confirmed through cutting and once a white sap is seen oozing, it means the seed is mature.

It is important to check if there are pests and disease and observe if the fruits’ colour changes from green to yellow, orange brown and black.

Seed processing
Orthodox seed obtained from legume tree species such as Calliandra contained in pods can be sun-dried by spreading them in direct sun for 1-2 days.

Farmers are expected to put them in a sack or spread on a polythene sheet and thresh by beating them with a stick. This is followed by seed cleaning through winnowing to remove inert material, damaged seeds or infected seeds. Sort out the left inert material and bad seeds by hand and dry the clean seeds to the right moisture.

Seeds that are contained in pulps from fruits such as mangos and Avocado can be processed by removing the pulp, dry the seed at the required moisture continent and store it appropriately.

Seed testing for germination viability
Seed test are used to verify seed quality and monitor seed conditions. These tests should be done immediately after processing or before storage and distribution.

The tests include; seed cleanness, germination percentage testing, viability test and moisture content test.

Seed cleanness test
Farmers must check if the processed seed contain debris including seeds of other species, pieces of fruits, twigs, leaves and any other dirt.

Germination test 
Pick a sample of seeds at random and the sample size should be two samples of 100 seeds per replication.

Sow the seeds in open trays or in nursery in a heap of sand or soil and count all germinating seeds and record the number. Germination period is from 4-90 days depending on the species and those that have failed to germinate, discard them.

Viability test
Seed viability can easily be tested by sampling 100 seeds from a seed lot. Pick the seeds at random and use a knife or sharp object to do cutting test.

Seeds with firm white sap are viable while the empty or dark or black are not viable and may be dead. Count the viable seeds to get viability percentage.

Moisture content testing
The amount of moisture in a seed can easily be tested for dry seeds like all orthodox seeds such as legumes.

This is done by filling one quarter of a glass jar with salt, add the seed sample enough to fill half of the jar and then close the lid tightly Shake the jar well for some minutes and if damp salt sticks on the sides of the jar, then the seeds are too moist for storage. If the jar is still dry and no salt is stuck on its sides then the seeds have less than 15 percent moisture content and can be stored safely.

Seed storage
It is important for farmers to adopt good storage practices which include seed storage room to have modified atmosphere with regulated temperature and humidity. It is possible to use a simple storage structure such as a charcoal storage cooler. This is made of a grass roof and charcoal walls to keep it cool.

The charcoal is enclosed in a mesh wire on both sides including the door. It is kept cool by pouring cold water on it to keep it moist. Seeds can be stored for different periods, depending on moisture content in seed and temperature during storage. Orthodox legume tree seeds can be stored in air tight containers and keep in a cool place.