Abstract:
Walla patta (Gyrinops walla Gaertn.) belongs to family Thymelaeaceae, is a valuable
endemic plant in Sri Lanka. Recently, this species has become a topic of wide interest
due to its ability to produce highly valuable agarwood resin. Commercial cultivation
of the species is yet to start, thus natural habitats are tremendously under pressure
due to illegal harvest. The seeds of G. walla are recalcitrant and loose the viability
within a shorter period of time. Due to the limited availability of information, the
present study was aimed at evaluating the effect of plant growth regulators on seed
germination. The experiment was conducted in a protected plant house at the Faculty
of Agriculture, University of Ruhuna from September 2019 to January 2020. A
completely randomized design (CRD) was used with three replicates. The influence
of gibberellic acid (GA3), indole-3-acetic acid (IAA), and indol-3-butyric acid (IBA) at
800 ppm, 1000 ppm, and 1200 ppm concentrations on seed germination of the G.
walla were investigated. Seeds soaked in nine different hormone solutions for 24
hours were placed in disinfected sand media and germinations were recorded daily
up to 60 days. Seeds treated with water served as the control. Final germination
percentage, mean germination time, mean daily germination, germination rate index
and average time taken to start the germination were recorded. Hormone treatments
except IBA at 1000 ppm, significantly increased (p<0.05) the seed germination, when
compared with the control. GA3 at 1200 ppm showed the highest (65%) germination
followed by IAA at 1000 ppm (53.33%) and 800 ppm (50%). GA3 treatments showed
a significantly (p<0.05) faster germination rate than IAA and IBA. Based on the
results, GA3 at 1200 ppm can be recommended to enhance the seed germination of
G. walla.
