Effect of branch position and auxin treatment on clonal propagation of Tectona grandis Linn. f.

Abstract

The main objective of our clonal propagation program is the production of high quality timber and faster tree growth. Teak (Tectona grandis Linn. f.) is an important plantation species in the tropics but the demand of teak timber is increasing globally. Teak planting stock is still produced from seeds of unselected elite genotypes which may lead to poor stand establishment. The number of seeds per fruit and their germination ability are also variable and limited by several factors. Therefore an alternative method i.e., clonal propagation is required for mass multiplication of elite trees. It is an established fact that the clonal propagation or adventitious root formation in cuttings is markedly affected by several external and internal factors. Considering these, an experiment was conducted on leafy soft wood shoot cuttings of 3-year-old hedged teak stock plants grown in a hedge garden to study the effects of branch position and auxin treatment on adventitious root formation. A factorial completely randomized design was used for experimentation. Coppice shoots were collected from basal, middle and upper positions of the hedge garden; and mono-nodal leafy cuttings were prepared. These cuttings were treated with different concentrations of IBA and NAA; and were cultured in a mist chamber for rooting where the relative humidity was maintained at 85 ± 2% with maximum and minimum day-night temperature at 32 ± 1°C and 26 ± 1°C respectively. After 45 days the cuttings were removed from the rooting medium and observations were made. It was observed that the rooting parameters viz., percent rooting and percent sprouting, mean number of leaves, mean number of shoots and length, and mean number of roots and length per cutting were significantly influenced by the branch position and auxin treatment. Treatment with 4000 ppm IBA increased percent rooting and percent sprouting whereas NAA suppressed it. Treatment with 4000 ppm IBA also increased the mean number of leaves and shoots, and the length, and the mean number of roots per cutting. The highest mean number of roots and length were observed in cuttings taken from the branch emerging at the upper position followed by branches of middle and lower position. Cuttings of branches at a middle position showed the highest values of percent rooting, percent sprouting, mean number of leaves and shoots and mean shoot length per cutting. Furthermore, the interactive effect of branch position and auxin treatment on rooting and sprouting response was also found to be significant. Overall, the findings of this investigation suggest that middle branch position in hedge plants and 4000 ppm IBA can be made to induce maximum rooting and to produce high quality planting stock material for clonal forestry program of teak.