Introductory Agroforestry (1+1)

REGENERATION

Artificial Regeneration: Poplars can be raised by the following methods.

(i) By Sexual Reproduction:

• The tree produces seed at intervals but it has low germination percentage.
• The seed of Populus deltoides has been germinated under laboratory conditions with germination percentage varying from 5.25 to 19.25%.
• The medium of germination, i.e. two parts soil and one part of river sand duly sterilized proved most effective and gave higher survival and best shoot development.
• Germination tests conducted about the viability of seed after 6 years of storage showed that -20°C storage was superior to -50°C storage in maintaining seed viability.
• Populus deltoides flowered for the first time in May, 1982 in Terai (U.P.).
• Poplar seeds are very minute and 14,000 seeds weigh one kg.
• The plant is rarely raised by seeds.

(ii) Vegetative propagation:

• Cuttings: Cuttings 18-25 cm long and 1-2.5 cm thick having at least four buds are directly planted in the field in well worked soils, keeping one bud above the ground. The soil around the cuttings is thoroughly compacted.
• Sets: A set is one year old cut back plant without root or a long stem cutting which consists of one year growth. The root portion left in the nursery can again be used to produce plant/set/cuttings for the next planting season. Sets are planted in 75 cm to 1 m deep pits. The length of set is about 3.5 m or more.
• Bag plants: These can be raised in polythene bags of 15cm x 23cm x 150 gauge filled with soil mix and treated with 5% aldrex. Cuttings are planted in these bags in February in the year of planting. Vigorous plants are not obtainable by this method.
• Stumps (Root-shoot cuttings): These are prepared from one year old nursery plants keeping 25 cm long root and 3 cm of shoot.
• Entire transplants (ETPs): This is the best method for transplanting poplars. These are one or two year old plants raised from cuttings in the nursery. While removing these plants, the root is cut at 25 cm depth and all side roots more than 10 cm long are also trimmed. The plants are taken out with naked root and without foliage.