TY - JOUR AU - Mohamed-Faisal M, AU - Umarani R, AU - Parthiban KT, PY - 2022/10/27 Y2 - 2024/03/29 TI - POOR SEED GERMINATION OF MELIA DUBIA— UNRAVELLING THE BIOLOGICAL CAUSES AND DESIGNING AN APPROPRIATE SEED TREATMENT PROTOCOL JF - Journal of Tropical Forest Science (JTFS) JA - JTFS VL - 34 IS - 4 SE - Articles DO - UR - https://jtfs.frim.gov.my/jtfs/article/view/1775 SP - 371-382 AB - <p><em>Melia dubia</em> produces indehiscent drupes which are sown for seed germination. Studies revealed that the germination is highly protracted, sporadic and the final germination is very low (&lt; 10 %). The exocarp and mesocarp of <em>M. dubia</em> fruits are impermeable to water (physical dormancy), while the endocarp causes mechanical resistance to germinating embryo (mechanical dormancy). The kernels extracted from the drupes responded well to GA<sub>3</sub> (250 mg L<sup>-1</sup>) treatment, when applied through seed soaking (24 hours) +<br />humid priming (2 days), compared to seed soaking (24 hours) in GA<sub>3</sub> (250 mg L<sup>-1</sup>) alone. Excavation of ungerminated seeds from nursery beds revealed that the remaining kernels were either fresh ungerminated (FUG) or decayed. This might be due to presence of a large proportion of low vigour seeds within a seed lot. Exposing the kernels to dry heat (40 oC for 4 hours) followed by seed soaking in GA<sub>3</sub> (250 mg L-1) for 24 hours + humid priming with GA<sub>3</sub> (250 mg L-1) for two days, and sowing in a polyhouse with high relative<br />humidity (80 ± 5 % RH) resulted in highest improvement in synchrony of germination, with corresponding decrease in FUG and seed decay. The protocol enabled to increase the seed germination of<em> M. dubia</em> to 42.3% and reduced the period of seed germination to 21 days. The poor germination behavior of <em>M. dubia </em>is attributed to multiple factors such as physical dormancy imposed by exocarp and mesocarp, mechanical dormancy caused by endocarp and higher proportion of low vigour seeds in a seed lot.</p> ER -