The Effect of Seed Treatments, Nursery technique And Storage Methods on the Germination of Tung Seed

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Webster, C.C.
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Seasonal climatic conditions in relation to Tung nursery work in Nyasaland are described and an account is given of experiments which aimed at reducing the time required to produce plants big enough to bud, and at minimizing watering costs, by accelerating the rate of germination of the seeds or by eliminating the loss of viability which normally occurs during storage of off soft material adhering to the shell; soaking in hot or cold water; grinding away part of the shell at the hilum end; cracking the shell either mechanically or by exposure to strong sunlight; the latter method, however, providing unreliable as a means of causing cracking. None of these treatments were effective in improving the germination of seed which had been stored for several months but grinding or cracking accelerated speed of germination and usually improved final germination of fresh seed. Neither method is very suitable for practical application on estates as no means of effecting the treatments mechanically without damaging a proportion of the seeds has been devised. Experiments on nursery technique showed that shading or mulching the nursery beds is undesirable- and that the position in which the seed is placed is immaterial unless the hilum end is pointing downwards, in which case the speed of germination and final percentage emergence is reduced. Sowing with l-inch depth of soil above the seed was better than with 2 inches depth. In the cool season watering on alternate days at the rate of 2 gallons per square yard was superior to daily watering at the same rate but in the hot season the reverse was' true. With a clone which matures its crop early, seeds taken from green fruit picked off the tree at the beginning of March and sown immediately gave a good germination but despite the early sowing the resulting plants were not big enough to bud by the end of the same year. On the other hand, with a clone which ripens its crop rather later, appreciably better germination was obtained from seed collected and sown at the beginning of May than from that sown two months earlier, indicating that the best germination is obtained if the seed is collected and sown when the fruits are just fully ripe. 41 Several methods of storage were tried but the only one which prevented loss of viability was by stratification in moist sand or sawdust. Seed which is merely mixed with moist sand and stored in boxes in a cool building will preserve its viability for periods of up to six and a half months and on planting will germinate very rapidly. Plants raised from such seed are ready for budding one year later and storage by this method therefore enables the time in the nursery to be shortened by five to six months and eliminates most of the expense of watering necessary throughout the dry season.
East African Agricultural And Forestry Journal, 14, pp. 38-48