Seed germination studies in Rhododendron maddenii Hook. F. and Rhododendron niveum Hook.F.

The genus Rhododendron constitutes a very important dominant combination in temperate, subalpine and alpine region of the Sikkim Himalaya. The present investigation was undertaken to examine the effect of various physical and chemical agents and plant growth regulators for enhancing uniform seed germination. Among the various plant growth regulators and chemicals tried, only a few could significantly influence seed germination over control. Seeds of Rhododendron maddenii, R. niveum in MS medium treated with GA₃ (250 μM) recorded maximum germination. The BAP did not enhance the seed germination in R. maddenii; BAP (250 μM) was infact inhibitory. On the other hand, in R. niveum, BAP enhanced seed germination. The combined treatments of gibberellins and BAP resulted in reduced germination in R. maddenii and enhanced germination in R. niveum. Among nitrogenous compounds, KNO₃ decreased germination in R. maddenii, and increased in R. niveum. However KOH solution was found to be beneficial in both concentrations. Seed germination percentage and seed vigour were decreased with the increase of storage time.