Effects of Light Intensity on Growth of Dialium Guineense Willd Seedlings
1Oyedeji, O.F. and 2A.O. Akinyele
1Forestry Research Institute of Nigeria. P. M. B. 5054, Jericho Hill, Ibadan, Nigeria.
2Forest Resources Management Department, University of Ibadan, Ibadan, Nigeria.
Abstract
Investigation was conducted on the effect of light intensity on the growth of seedlings of Dialium guineense at the Forestry Research Institute of Nigeria, Ibadan, Nigeria. One hundred and twenty (120) seedlings were transplanted into polythene pots placed in cages with 1 layer, 2 layers and 3 layers of 1mm green plastic mesh to receive 75% (L2); 50% (L3) and 25% (L4) respectively. Seedlings in the open received 100% light (L1). Ten (10) seedlings per treatment were assessed weekly. Leaf, stem and root biomass were determined fortnightly. Relative Growth Rate, Absolute Growth Rate (AGR), Net Assimilation Rate (NAR) and Shoot-Root Ratio (SRR) were determined. Data collected were analysed using ANOVA at = 0.05 and LSD was used to separate significant means. Significant difference was observed in stem diameter and Total Dry Weight (TDW) among the different light intensities. Seedlings exposed to 100% light intensity had highest TDW (0.577g) while those under 25% intensity had the least (0.232g). The highest mean value for RGR and AGR were found in seedlings raised under 100% light intensity while those under 75% and 50% had the least values of 0.036g/wk and 0.012g/g/wk respectively. The highest NAR (0.0108g/cm²/wk) was however recorded in seedlings under 75% light intensity and the least (0.0077g/cm²/wk) found in 50% light intensity. Exposure of seedlings of D. guineense to 100% light intensity therefore enhanced their growth and dry matter accumulation.