Synchronism of leaf development and leaf elongation rates of contrasting rice (Oryza sativa L.) genotypes
2014
Egle, R.B.
Leaf appearance and leaf elongation rates in rice play essential roles in determining the plants' differences in development of their architecture, which is related to their adaptability to varying environments and coping mechanism with change. This study aimed to characterize the rates of leaf appearance and elongation of all leaves of the main tillers of contrasting rice plants, and to determine the relationship that exist between the two rates. Eleven contrasting rice genotypes were grown in 13-L pots under flooded conditions in a greenhouse at the International Rice Research Institute [Philippines] in June and September 2013. In contrast with previous reports of bilinear kinetics of leaf appearance, the study revealed trilinear kinetics in most varieties across sowing dates because the first four leaves appeared faster, rendering two inflection points. Leaf elongation rate (LER) of all genotypes increased linearly with leaf rank until it reached leaves 9 to 14 then it gradually decreased. Thus, the leaf with maximum LER was the last leaf to appear before the rate of leaf appearance was reduced. A transition period between the two linear parts of the leaf appearance curve, covering 3-4 leaves, was found in genotypes with trilinear kinetics. The precise methodology employed led to the discovery of transition period across genotypes and sowing dates, which was not captured in previous studies. This finding will avoid overestimation in the simulation of leaf are and will improve database for breeding and crop improvement. Further research on the cellular level is needed to determine the activity of meristem cell division and elongation.
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