Abstract:
Tropical rice varieties require high light intensities to achieve their potential
grain yield. However, in the Sri Lankan context, there is a limited amount of
research focusing on the effects of light on commercial rice varieties. The
main objectives of the experiment were to investigate the effect of varieties
on the growth and yield attributes of six rice varieties under 50% shaded
conditions. A pot experiment was conducted in a plant shade (50%) house to
evaluate the growth and yield performance of elite rice cultivars, namely,
Bg360, Bg310, Bg403, Bg379/2, Bw367. According to the results, the
maximum plant height was observed in Bw367 at the 13th week after
planting (77.5cm), surpassing AT362 (70.4cm), while Bg360 recorded the
lowest (58.3cm). The flowering days were substantially delayed in the
control variety AT362 (83 days) and further delayed in Bg379/2 (109.7 days).
The highest number of tillers were produced in Bg360 (8.6/plant) compared
to AT362 (7.5/plant), while Bw367 recorded the lowest number of tillers
(6.3). Furthermore, the highest number of panicles per plant was produced in
Bg379/2 (4.4) compared to AT362 (3.9), with Bg310 having the lowest mean
value (3.2). Bw367 recorded the highest grains per panicle (192.8), while
AT362 recorded (107.2), and Bg360 recorded the lowest (83.0) respectively.
The highest panicle fresh and dry weight was recorded in Bw367 (3.66g,
1.28g respectively) compared to AT362 (2.54g, 0.67g respectively), while
the lowest was in Bg360 (2.12g, 0.54g respectively). Therefore, the results
indicate that commercial rice varieties grown under shade conditions
perform sub-optimally, and farmers need to consider the light requirements
of plants before selecting varieties
