Tube Diameter And Age Of Seedlings. Two Nursery And Field Experiments Pinus Caribaea. Uganda

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Gunnar L.
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Ministry Of Agriculture
The present Technical Report deals with two combined nursery and field experiments, both with Pinus caribaea var. hondurensis and with identical treatment plans. The object was to study the effect of different tube diameters and varying lengths of time in the nursery, related to both nursery and field performances of the plants. The standard practice of tube diameter used in Uganda is 6.5 em diameter (4 inches lay-flat). The plants have an average height of 30 em, raised eight months in nursery before planting out. The standard length of the tubes is 15.2 em (6 inches), and this is the tube-length also used in the two present experiments. Reducing the tube diameter to 4.9 ems (3 inches lay-flat) means great savings in soil quantity and total nursery cost. It has been thought that the quality of the planting stock is to a certain extent determined by the tube diameter. A choice of tube diameter should therefore be based upon the two aspects: economy and plant quality. Plant quality is, however, hard to define by visual criteria, but rate of survival and growth after outplanting in the field are both good indicators of plant quality. This is why the experiments have been followed up in the field.