Impact of seed priming techniques on germination and seedling performance in sandal (Santalum album L.)

Abstract

Santalum album L, known as the East Indian Sandalwood is a semi-root parasitic tree native to South India and it is one of the most precious and valuable among Indian forest trees. The poor rate of germination coupled with long germination period is the major constraints in the regeneration of sandal. Present study was conducted to assess the impact of seed priming techniques on the germination and seedling growth attributes of sandal at College of Forestry, Vellanikkara, Thrissur. The effect of different duration and concentration of priming agents viz. water (Hydropriming for 3, 6, 9 and 12 days), Pseudomonas fluorescens (Biopriming at 25, 50, 75 and 100% for 2, 4, 6 and 8 days), Polyethylene Glycol 6000 (Osmopriming at 5, 10, 15 and 20% for 3, 6, 9 and 12 days) and MnSO4 (Chemical priming at 0.4, 0.6, 0.8 and 1.0 M for 3, 6, 9 and 12 days) on seed germination and subsequent seedling growth in sandal were studied. The non- primed seeds were kept as control. Primed seeds were stored for one day and one month after the completion of priming processes and the germination and seedling growth were observed. The germination was obtained only in the seeds stored for one day after priming process and the seeds stored for one month failed to germinate. Results indicated that the hydropriming of the seeds could not improve the germination of the sandal seeds compared to control. Biopriming significantly increased the seed germination and the highest germination percentage (88%) was recorded in the seeds subjected to biopriming for 8 days at 100% concentration, which was 1.9 times higher compared to control. The highest germination recorded in osmopriming was 78%. The chemical priming with MnSO4 at different concentrations for 3 days also recorded the higher germination (88%) comparable to biopriming. Electrical conductivity was the highest in the leachates of seeds hydroprimed for 12 days (1.96 dS cm-1) and was the lowest in seeds subjected to biopriming (0.03 dS cm-1). The leachate conductivity of the seeds subjected to osmopriming treatments (1.69 dS cm-1) was comparable to that of the hydropriming treatments. Although the different concentrations and duration of MnSO4 reduced the leakage of solutes from the sandal seeds, the electrical conductivity was higher than that of the biopriming treatments. Hence, biopriming treatments were the best in reducing the leakage of solutes from the cells leading to better membrane integrity and stability. Biochemical analysis of the primed and non-primed seeds indicated that the hydropriming treatments recorded significantly lower carbohydrate, protein and crude fat content compared to control.