Genetic Base and Improvement:

About 90 percent of the poplar plantations in India are based on clones G-48, D-121, S7C15 and G-3. The yield of clone G-3, which once used to be the most popular clone, is declining due to attack by leaf blight disease. This clone is giving way to other clones, e.g., S7C8, Uday, L-34/82 etc. Individual plantations are, however, monoclonal (Kumar et al, 1998).

To increase the productivity of poplar, FRI Dehradun started a National Poplar Improvement Programme in 1997. Salient achievements of this initiative are:

(i) Clones of poplar introduced in India since late-1950 were ranked on the basis of volume growth. Clones S7C8, 82-35-4 and 113324 were found to give higher yield than G-48, presently one of the most popular clones in agroforestry plantations. Based on these rankings, a vegetative multiplication garden was established at FRI, Dehradun to supply cuttings of superior clones to growers.

(ii) Multilocation field trials of best 60 clones of previous introduction have been established at about 30 sites throughout the traditional as well as potential zones of poplar cultivation covering Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Uttar Pradesh, Bihar, West Bengal, Orissa, Chhattisgarh, Maharashtra, Gujarat, etc. Fifteen Research Institutions comprising Universities, State Forest Departments are collaborating with FRI, Dehradun in this programme.

(iii) Intraspecific hybridisation amongst best 40 clones has been carried out. 289 clones from control-pollination and 111 clones from open-pollination have been selected for field trials.

(iv) Seed from 104 candidate plus trees growing in 44 natural stands in the USA has been brought to FRI Dehradun. 100 clones have been selected out of the new germplasm for further trials (Singh et al,2003).

(v) A new approach of multi-step selection and concurrent multiplication has been developed at FRI Dehradun which enables multiplication of germplasm of superior clones at 2 years of age while clonal trial is stilI underway. This reduces the time period in clonal testing and multiplication process by 4

years (Kumar and Singh, 2000).

(vi) Hybrid seedlings of P. deltoides 'G-48' x P. euphratica have been produced to combine the rapid growth of P. deltoides and stress tolerance of P. euphratica (Singh et al, 2003)

Cultivation practices

Eucalyptus, generally raised for industrial plantations - mainly pulpwood, firewood or poles, are maintained with a shorter rotation of 5-7 years. For commercial plantations, intensive site preparation by ploughing or deep ripping on compact sites, is beneficial. On wet sites moulding should be adopted to improve root aeration and provide well-drained condition that facilitate planting. Spacing adopted is 2m x 2m in commercial plantation. In case, crops are cultivated between the rows (agroforestry), wider spacing of 4m x 2m ; 6m x 1.5m or 8m x 1m are recommended. Nursery raised seedlings/plantlets in polybags may be planted at the onset of monsoons, in pits of 45 cm x 45 cm x45 cm. Organic manure mixtures along with fertilizers containing 100g of NPK (4:4:2). Protective irrigation is essential, in case of monsoon failure, in the first two years of plantation. Eucalyptus is intolerant to shade and does not compete well with grasses for water and nutrients, thus 2-3 hand weeding and soil working in the initial stages are essential.

Owing to its fast growth, Eucalyptus is a heavy feeder and requires supplements in form of organic and chemical fertilizers in successive years. Deficiency of Nitrogen in soils is a limiting factor for growth and can reduce the yield by 60%. For maintaining the soil fertility, it is advisable to raise Eucalyptus trees with legumes as an intercrop.

  Harvesting is done by clear felling the stand in 6-7 year. Once the tree is felled, the stump throws many coppice shoots. These should be singled out to keep only one vigorous stem per stump, which will form the second crop. It is advisable to change the planting stock after the second harvest, as there is loss in vigour in coppice from the third coppice onwards.