Abstract:
Wild rice species, Oryza nivara is the progenitor of Asian cultivated rice and has been
recognized as a valuable genetic resource for rice genetic improvement. In Sri Lanka,
reciprocal transplant studies of wild rice species are limited. This study fulfils the
knowledge gap on morphological variation of O. nivara grown in native and
introduced environments for evaluating phenotypic variation for local adaptation. The
reciprocal common garden experiment was conducted in the dry (Hambantota:
N6.232684, E81.147097) and wet (Akuressa: N6.162225, E80.42886) zones of Sri
Lanka. Phenotypic plasticity was measured by 8 quantitative traits following the rice
descriptor published by IRRI. The independent t-test revealed that the all quantitative
traits of O. nivara showed a significant difference between the dry and wet zones.
According to the results, significantly highest culm length (78.4 ± 11.2 cm), anther
length (3.38 ± 0.34 mm), awn length (66.9 ± 14.9 mm), panicle length (24.66 ± 3.25
mm), and plant height (101.2 ± 23.3 cm) were recorded in the wet zone. However, the
dry zone showed the significantly highest culm diameter (8.21 ± 1.23 mm), flag leaf
angle (850
), and horizontal distribution (145.0 ± 17.4 cm) compared to the wet zone.
Oryza nivara was mostly confined to the dry zone thus, its phenotype was more
prominent in the wet zone when compared to its native habitat. The investigation of
phenotypic plasticity provides a new clue for the local adaptation and speciation
studies and the effective use of wild stains in the development of location-specific
modern cultivars.
