BIOCHEMICAL MECHANISMS ASSOCIATED WITH DORMANCY IN TEAK (<em>TECTONA</em> <em>GRANDIS</em>) DRUPES AND TRUE SEEDS
Keywords:Propagation, physical parameters, seed filling, germination, gibberellic acid, coumarin
Poor seed germination is a significant obstacle in the propagation of teak and may be due to dormancy but the specific mechanism has not been explored. In order to investigate the physiological mechanisms (promoters–inhibitors) involved in teak seed dormancy, teak drupes were collected from seven provenances of India ranging across four forest types. The collected drupes were used to study morphological, physiological and biochemical characters. Teak drupes collected from moist deciduous forest (Tamil Nadu) recorded significantly higher physiological parameters while drupes collected from semi-deciduous forest (Maharashtra) recorded the highest seed filling of 94%. Gibberellic acid, was found in all seven provenances of teak seeds. The highest levels of gibberellic acid (1.96 mg kg-1) in seeds were found in very moist deciduous forests in Kerala and dry deciduous forests in Andhra Pradesh. The presence of biochemical inhibitor coumarin in teak seeds of highly moist deciduous forest (Kerala) (1.88 mg kg-1) is reported for the first time in this paper. The findings suggest that coumarin is leached out during alternate soaking and drying before seeding teak drupes and this did not influence the germination of teak. Drupe and seed extracts of teak did not contain growth regulators such as indole-3-acetic acid, indole butyric acid and abscisic acid.