A Quantitative Analysis on Leaf Curvature Characteristics in Rice

Abstract

With rapid development of computer graphics and crop simulation, virtual crop study that can intuitionally express crop growth on computer has attracted great attention from many scientists in the world, with significant progress on visualization of crop plants. In virtual crop modeling, leaf shape is a very important character, and has been described with empirical curves derived from field experiments in the previous studies. The fitting curves are helpful for understanding organ morphogenesis, but the parameters obtained from the specific leaves and environments are not well adapted to changing growth processes of leaves. So it is critical to develop a dynamic model for simulating the leaf morphology under different growth conditions. Organ morphogenesis of plant is associated with its forces. From force analysis on a rice leaf, the gravity fraction in leaf normal direction keeps equilibrium with elasticity, then a dynamic leaf curvature equation was deduced with some assumptions. The equation included the synthetic effects of leaf blade length, leaf blade width, initial leaf angle, specific leaf weight and deformation coefficient on leaf space shape. Then the equation was solved with parameterization. The sensitivity analysis showed that the equation could well reflect the integrated effects of leaf length, leaf width, specific leaf weight and leaf deformation coefficient, consistent with rice plant architecture in practice. A field experiment was conducted at the Nanjing Agricultural University using two rice cultivars (SU63 and WYG7). At jointing and booting stages of rice, the 3-dimension coordinates of several points along leaf midrib were measured with the 3D digitizer, and at the same time leaf blade length, width, initial leaf angle were obtained. Then simulation analyses on the equation were conducted for comparison with the experiment data. The results indicated that the leaf curvature equation could dynamically and reliably describe the change pattern of leaf shape characteristics of rice under different conditions, including different leaf angles and specific leaf weights.