Rhododendron meaning “red tree” broad genus having almost 1,200 indigenous Rhododendron species are present globally1. This tree has much significance regarding conservation in Taiwan because propagation is done through cutting method which leads to less genetic diversity because of narrower genetic makeup of Rhododendron species2,3. Therefore; sexual propagation should be adopted which is finest technique for genetic conservation4.
The number of seedlings can assist to evaluate the plant distribution and abundance5,6. And the seed germination is affected by various factors of light including light intensity, light quality and photoperiod7. Olson8 and Cho9 reported that light is indispensable for seed germination in Rhododendron species and red light having wavelength 660 nm; can promote seed germination10. Photoperiod (time period for which a plant or animal is exposed to light during 24-hours) is also significant in this regard and according to some investigations the optimal photoperiod for Rhododendron seed germination is 24 h11,12.
Accordingly; Lei-Chen Lin and Chang-Sheng Wang designed a study to assess the rate and trend of seed germination of four Rhododendron species in Taiwan under different light intensities and photoperiods. In this research, scientists followed the two sets of experiments on the seed germination percentage of R. breviperulatum, R. kanehirai, R. ovatum and R. simsii. Seed germination percentage of these four species was determined by employing different light intensities (0, 700, 1400 and 3200 lux) in the first experiment. While in 2nd experiment seed germination percentage was identified for four different photoperiods (0, 1, 4 and 16 hours). All statistical analyses were conducted through Statistical Package for the Social Science (SPSS12.0) for Windows software program. Moreover, Tukey’s multiple range test at the p<0.05 significance level was used to examine the data.
No seed germination was observed after 30 days in darkness. Researchers noted the maximum average seed germination percentages at 700 lux: R. breviperulatum (83.3%), R. kanehirai (68.9%), R. ovatum (85.6%) and R. simsii (92.2%). The highest average germination percentages of seeds were observed in R. breviperulatum at 16 h (83.3%), R. kanehirai at 1 h (60.0%), R. ovatum at 16 h (84.4%) and R. simsii at 16 h (85.6%). Results exhibited that these four Rhododendron species need light for germination. Conclusively; scientists stated that the seed germination percentage of R. breviperulatum, R. ovatum and R. simsii accelerate with amplification in photoperiod.
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17 November, 2019