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International Journal of Agronomy
Volume 2013 (2013), Article ID 878246, 8 pages
http://dx.doi.org/10.1155/2013/878246
Research Article

Estimation of Blast Severity on Rye and Triticale Spikes by Digital Image Analysis

1Embrapa Trigo, BR-285, Km 294, CP 451, 99001-970 Passo Fundo, RS, Brazil
2Faculdade de Agronomia e Medicina Veterinária, UPF, Campus I, BR-285, Bairro São José, CP 611, 99052-900 Passo Fundo, RS, Brazil

Received 9 July 2013; Accepted 5 September 2013

Academic Editor: A. V. Barker

Copyright © 2013 João Leodato Nunes Maciel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In Brazil, more efficient methods are a necessity for evaluating blast severity on spikes in the breeding programs of rye, triticale, wheat, and barley. The objective of this work was to determine the feasibility of assessing blast severity based on the analysis of digital images of symptomatic rye and triticale spikes. Triticale and rye genotypes were grown to anthesis in pots and were then inoculated with a mixture of Magnaporthe oryzae isolates. Blast severity on the spikes was evaluated visually and after that the spikes were detached and photographed. Blast severity was determined using the program ImageJ to analyze the obtained images. Two methods of image analysis were used: selection of symptomatic areas using a mouse cursor (SCU) and selection of symptomatic areas using image segmentation (SIS). The SCU method was considered the standard reference method for determining the true value of blast severity on spikes. An analysis of variance did not determine any difference among the evaluation methods. The coefficient of determination (R2) obtained from a linear regression analysis between the variables SIS and SCU was 0.615. The obtained data indicate that the evaluation of blast severity on spikes based on image segmentation is feasible and reliable.