Performance and Analysis of a Model for Describing Layered Leaf Area Index of Rice

Layered leaf area index (LAIk) is one of the major determinants for rice canopy. The objective of this study is to attain rice LAIk using morphological traits especially leaf traits that affected plant type. A theoretical model based on rice geometrical structure was established to describe LAIk of rice with leaf length (Li), width (Wi), angle (Ai), and space (Si), and plant pole height (H) at booting and heading stages. In correlation with traditional manual measurement, the model was performed by high R2-values (0.95-0.89, n=24) for four rice hybrids (Liangyoupeijiu, Liangyou E32, Liangyou Y06, and Shanyou 63) with various plant types and four densities (3 750, 2 812, 1 875, and 1 125 plants per 100 m2) of a particular hybrid (Liangyoupeijiu). The analysis of leaf length, width, angle, and space on LAIk for two hybrids (Liangyoupeijiu and Shanyou 63) showed that leaves length and space exhibited greater effects on the change of rice LAIk. The radiation intensity showed a significantly negative exponential relation to the accumulation of LAIk, which agreed to the coefficient of light extinction (K). Our results suggest that plant type regulates radiation distribution through changing LAIk. The present model would be helpful to acquire leaf distribution and judge canopy structure of rice field by computer system after a simple and less-invasive measurement of leaf length, width, angle (by photo), and space at field with non-dilapidation of plants.