1 JOURNAL OF TROPICAL FORESTRY JULY-DECEMBER, 2008 VOL. 24 (III &IV)-   EFFECT OF HOT-WATER TREATMENT ON SEED GERMINATION OF SOME FAST GROWING TROPICAL TREE SPECIES Sanjay Sharma, Ranjana Naithani, B. Varghese, S. Keshavkant and S.C. Naithani* Seed Biology Lab, School of Life Sciences Pt. Ravishankar Shukla University, Raipur 492 010 (India) Phone : 0771 2263038 (O) 2262536 (R) Fax : 0771 2262583, Email :naithani_nib@sancharnet.in Abstract Seeds of fast growing tropical tree species, viz., Albizzia lebbek, Albizzia procera, Peltophorum pterocarpum, Acacia auriculiformis and Leucaena leucocephala, were treated with hot water to overcome physical dormancy due to hardseededness. Compared to untreated seeds that showed 9-12% germination in 17 to 20 days, the brief exposure (1to10 minutes) of hot-water (100 o C) treatment promoted germination by 7 to 9 fold (94 to 100%) in a very short period (4 to 6 days) after imbibition. We conclude that the best hot-water presowing treatment for seeds A. lebbek and P. pterocarpum is 1 min (94 and 97% germination respectively), L. leucocephala is 5 min (100% germination), A. procera and A. auriculiformis is 10 min (94 and 98% germination respectively). Key words: Germination, hardseededness, Hot-water treatment, Tree species, Mimosaceae. INTRODUCTION Seed dormancy in Mimosaceae, Leguminoceae, Fabaceae, Malvaceae, Anacardiaceae (Barton, 1965 ; Rolston, 1978) Myrtaceae, Cupressaceae and Pinnaceae (Schmidt, 2000), is generally controlled by a hard and impermeable seed coat which must be modified to permit germination. The hard seed coat prevents imbibition and gaseous exchange that leads to physical dormancy and subsequently the foremost cause in poor and erratic germination. Overcoming hardseededness is an important initial step in the use of a range of species in restoration ecology programmes. Bulk, physical scarification using macerators and grinders produced unreliable results with Leucaena leucocephala (Gosling et al., 1995). Site directed thermal scarification using a glow- burner is highly successful but there is a risk of random damage to the embryo (Poulsen and Stubsgaard, 1995). Hot-water treatments have been used successfully on large number of tropical and sub-tropical seeds (Doussi and Thanos, 1994 ; Prasad and Nautiyal, 1996 ; Doran et al., 1983) and in forestry for rural development programmes (Masamba, 1994 ; Muhammad and Amusa, 2003), this treatment yielded additional benefit of controlling coat-borne pathogens (Hoersten and Luecke, 2001). The objective of the present communication is to improve seed germination percentage with faster rate by applying hot-water treatment in species like Albizzia lebbek, Albizzia procera, Peltophorum pterocarpum, Acacia auriculiformis and Leucaena leucocephala, which belong to family Mimosaceae and have been known to suffer with hardseededness. All these tropical tree species are fast growing and high biomass yielding and preferred widely in plantation programmes. * Corresponding author.