Growth and productivity potential of Dalbergia sissoo in short rotation coppice system on sodic soil

Abstract

Performance of five year old coppice plants of Dalbergia sissoo was evaluated for biomass production on a sub-standard soil site. Initially coppice plants showed emergence of 4.59 + 1.65 sprouts per stump followed by dominance of 2.2 + 1.00 shoots per stump after five year of growth. Dominant shoot attained an average height of 535.21+26.25 cm and a diameter of 4.52+1.88 cm at 130 cm from ground level. Accordingly, the basal area per shoot was 16.57 cm2. Different regression models were developed with various growth parameters to predict biomass of coppice shoots. Linear regression equation ‘y = a + b (d2h) (height and diameter of coppice shoot) was found to be the best predictor of biomass followed by diameter (d2) and height alone because of high value of correlation coefficient (p>0.001, p<0.01). At the age of 5 years, coppice shoots produced a total of 13.52 Mg ha-1 aboveground biomass with maximum stem wood (9.84 Mg ha-1), followed by branch wood (2.92 Mg ha-1) and leaf (0.781 Mg ha-1) respectively at the density of 2406 coppice stems ha-1. Accordingly, biomass allocation to different plant components revealed high proportion of woody biomass (94.3%) and marginal contribution of leafy portion (5.7%). Mean annual increment (MAI) on the basis of total above biomass was 2.70 Mg ha-1 whereas the current annual increment was 5.75 Mg ha-1. The usable energy content in woody biomass was 263.6 GJ ha-1 after five years of growth with acceptable heating value (20.66 + 1.25 kJ g-1) and reasonably good fuel value index (958.91 + 171.8). Morphologically superior plants “Plus trees” were retained as standards for a good seed source adaptable to such fragile sites. Thus our study revealed potential of short rotation coppice system in D. sissoo for obtaining biomass energy and minor timber on sub-standard soil sites.