Clustering of selected Sri Lankan rice (Oryza sativa L.) cultivars based on plant architecture and evaluation of their association to relative water content under drought

Certain rice cultivars when get exposed to drought, develop morphology that enables them to acquire drought tolerance. In addition, general morphology of a plant before its exposure to drought may also be a determinant of its final response to drought. Ten Sri Lankan rice cultivars were clustered according to ten morphological parameters under well-watered conditions and their associations to relative water content (RWC) under drought was assessed. The cluster analysis, and the component 1 of principal component (PC) analysis (mainly contributed by plant height (PH), leaf length (LL) and culm length (CL)), grouped the cultivars as traditional and newly-improved (exception Kalu Heenati). No significant (p<0.05) difference in RWC under drought was detected on 5^th, 12^th and 18^th day after imposing drought (DAID). When PC2 (mainly contributed by leaf width (LW) and leaf angle (LA)) and PC1 are considered together, the groups were significantly (p<0.05) different in RWC on the 12^th DAID. Hence, PH, leaf length (LL), CL, LW and LA before exposure to drought has an effect on the RWC of a plant under drought.