- INTRODUCTION
Trees can be propagated from cuttings or sowing seed. The time for sowing seeds is from mid-July to the end of the first week in August. In plantations the young trees will be planted out in lines 2.5m apart with 2.5m between the lines. This gives 1 600 trees to the hectare so that when you know the area you wish to plant, you can find out how many seedlings you need. Containers should be filled with soil early in July, ready for sowing the seed, directly into eachcontainer.
2. CHOICE OF SITE AND NURSERYPRACTICE
Any area which can be watered and has a deep, fertile, well-drained soil is suitable. Flat land is not necessary and sloping areas are just as suitable under irrigation. Doloritic soils provide good nursery sites. When propagating from cuttings, only material from 1 year old shoots should be used. Coppice shoots from stumps and leading shoots of trees between 1 and 6 years provided the best material is used. Shoots from 3mm to 6mm in diameter can be used. Selected material should be cut to 22 – 25 cm lengths with bush knives or secateurs. It is sometimes convenient to cut the lower end at an angle so that the slip can be more easily pressed into the nursery soil. Cut slips should be bundled into hundreds and left to soak for at least 2 days. An area which gets waterlogged or is susceptible to heavy frost must be avoided. If the nursery is to supply plantations over a wide area it should be close to the road so that vehicles can collect theseedlings.
You should take 10g of seed of E. grandis (saligna) or E. camaldulensiswhich is enough to produce 1000 seedlings and 10g of seed of E. teretcornisenough to produce 500 seedlings. You will see from this that the seed is very small, but these amounts will be ample.
The containers should be filled with soil in early July, for sowing into each container. The containers should be placed closely together on carefully levelled soil.
Remember, the young plant must get off to a good start to produce healthy, well-grown seedling by planting time. Use good topsoil and sieve out or take out any roots or stones before filling the pockets with the soil. A funnel of metal, or even cardboard, is not essential, but will help in filling the pockets. If you want to make your own funnel or can get one made the design shown on the following page is very suitable. The soil should be firm in the containers with the top of the soil about 1 cm below the container. As stated before the best sowing time is around mid July otherwise it is difficult to be sure of getting big enough plants (25 to 30cm tall) by late November which is the earliest planting-out time. However, frosts are still common in July and may affect the seed germination or damage the seedlings just after they germinate. It is therefore sensible to watch the weather and wait and see if there are still frosts. Do not delay sowing until after the end of the second week inAugust.
The actual sowing of the seed must be done carefully. The most common fault is to cover the tiny seed with too much sand or soil so that, although the seeds germinate, the shoot never reaches the surface. Controlling the depth of sowing is fairly simple if a tool made of wood is used. Below you will find a diagram showing you how to make such a tool, together with its measurements. After thoroughly moistening the soil in the pockets, the tool is used to make them ready for sowing the seed.
The seed is very small and only a very small quantity is needed in each pocket. If too much is used
valuable seed will be wasted. Take an ordinary 5 inch nail and dip it head first into the seed at an angle of about 45 degrees. When the nail is withdrawn, the very small amount of seed left on the nail head is the right amount of E. grandisor E. camaldulensisto sow in each container in the centre hole or depression. On page 4 you will find a diagram and picture showing how to measure the seed you need. For E. tereticornis. Two dips of the nail are necessary to provide enough seed for one container. When all containers are full, cover the seed with a sprinkling of dry sand. The sand should just fill the depression plus the thinnest of layers over the surface of the rest of the soil in the container. Immediately after sowing and covering the seed cover the containers with a thin layer of combed grass. This cover helps prevent scouring and washing of the soil when watering. A watering can with a fine rose (a spout attachment with small holes which produces thin jets of water) must be used for the same reason. Watering should normally be carried out in early morning and late afternoon and not during the heat of the day. Containers must be kept free of weeds and not over- watered.
The seed should start to germinate in a week to a fortnight, although if the weather is very cold germination may be delayed until a little later. Most of the seed will have finished germinating in about 4 to 5 weeks and the grass cover can then be removed. Seedlings grow quickly and soon the largest seedlings in the containers will have from 2 to 4 leaves and be 20 to 25mm tall. Water the containers thoroughly at this stage and remove the small seedlings keeping only the strongest ones.
Figure 1: Size and shape of metal funnel for filling polythene tubes or pockets
Figure 2: Picture of punch used to make an indentation in the top of the bags that have been filled with growing media. Below is a nail that is used to measure the amount of seed to be planted in each bag
In order to protect the seedlings against attack by termites during their first year after planting, seedlings should be treated with a recommended insecticide. The young trees are most vulnerable towards the end of their first dry season after planting before their roots have gone deep enough to reach soil which still has some moisture in October.
With open-ended tubes, the roots will grow through the bottom of the tube into the soil below after the seedling has grown to about the same height as its tube. Tubes must be lifted (root-pruned) every 2 to 4 weeks, in order to stop the roots growing too far into the soil below the tube. This also encourages a mass of fine roots to develop inside the tube, which holds the tube soil together. This should be done immediately after the plants have been watered. Before seedlings are about 25 to 30cm roots will be noticed growing out of the bottom of the containers and seedlings in tubes will already have had to be root-pruned, perhaps more than once.
Commercial nurseries propagate tree seedlings by a method called cuttings. A mother plant is propagated where slips of the tree are taken from her and propagated in seedling trays. The cuttings go through a process of special pruning and a rooting hormone is added to aid with root development. The reason why cuttings are used is because the tree characteristics are already known and eliminates the uncertainty that seeds and cross pollination may present. This is a very intensive method of seedling propagation and requires a high level of expertise and experience. Most of the cuttings that are propagated, (up to 80%) do not survive and dieoff.
Figure 3: Make sure the roots are straight in the hole made to receive it
Figure 4 and 5: Planting little seedlings into polythene bags (left) seedlings must be watered regularly using a fine rose (right)
Source:www.bwint.org Source: save-mount-kenya-forest.org
Figure 6 and 7: Shows a nursery of young trees growing under shade trees (left) and one cane use grass as partial shade for newly planted seedlings (right)
