Quantitative Evaluation of Weedy Rice Seed Shape Based on Elliptic Fourier Descriptor
Weedy rices are major sources of problems in the rice agroecosystem as they resemble cultivated rice in terms of general morphology. There is therefore a need to understand this group of weeds so proper management and control could be designed by crop managers. Despite the presence of these weeds in the environment, nothing is known about its true nature especially how they evolve and has become a great problem in the rice environment A detailed analysis of variability in terms of seed shape and its relationship to cultivated rice types is a welcome idea. In the current study, we use image analysis using geometric morphometric (GM) tools to understand the shape of the seeds of these weeds and compare it with cultivated rice types. Elliptic Fourier analysis was applied in this study where variations of angles of each contour of the outlines expressed in terms of eigenvalues were processed under Principal Component Analysis (PCA) based on variance-co-variance matrix. To summarize the result, shape space was constructed using the first 3 Principal Component scores (PCA) that have contributed large variations. To determine association and relationships among weedy rice (coded WRNE and WRILO) and the cultivated types (coded PSBRcs), cluster analysis was performed. Results revealed significant differences in shapes among 12 weedy rice agro-ecotypes and 2 cultivated PSBRc cultivars. The observed variations of 70％ were contributed by the first four principal components (PC 1 to PC 4). All weedy rice populations appear to have close phenotypic relationships with the PSBRc 82 based on similarity index, except WRNE 4 (sample population from Nueva Ecija) and WRILO 3 (sample population from Iloilo) which cluster around PSB Rc64. Both these groupings are highly supported by bootstrap value of 67％ after 1000 re-samplings. The results indicate that there are weedy rice types that have common shapes with cultivated types. Likewise it can be seen from the results that differentiation between selected weedy rice types also occur which means that weedy rice types are very much variable in terms of seed shapes. It can be deduced also from the results that the tools of GM is very useful in understanding the shape of the seed quantitatively.
Fourier geometric morphometrics weedy rice
Dennis A. Apuan Mark Anthony J. Torres Cesar G.Demayo Madonna Casimero Leocadio S. Sebastian
Department of Agricultural Sciences, Xavier University Cagayan de Oro City Biological Sciences Department College of Science and Mathematics MSU-Iligan Institute of Technology Philippine Rice Research Institute Science City of Munoz, Nueva Ecija Philippine ice Research Institute Science City of Munoz, Nueva Ecija
国际会议
昆明
英文
391-394
2010-10-17（万方平台首次上网日期，不代表论文的发表时间）