Standard area diagram set for bacterial spot assessment in fruits of yellow passion fruit

Abstract This study developed and validated a standard area diagram set (SADs) for severity assessment of bacterial spot (Xanthomonas axonopodis pv. ) in passifloraefruits of yellow passion fruit (Passiflora edulis). The SADs consisted of eight severity levels (1%; 3%; 5%; 10%; 21%; 38%; 65%; and 80%). For its validation, 20 raters, who initially estimated the disease severity without the aid of the SADs, were divided into groups (G1 and G3, inexperienced; G2 and G4, experienced). Subsequently, G1 and G2 performed the second evaluation without the proposed SADs, and G3 and G4 completed the second evaluation using the proposed SADs. The accuracy and precision of the assessments were determined by simple linear regression and by the Lin’s concordance correlation coefficient. The increase in the accuracy was confirmed by the reduction in the constant and systematic errors, indicating that the estimated severities were close to the actual values when the SADs was used. Inexperienced raters benefited the most from the use of the SADs, and 60% and 100% of them presented constant and systematic error-free estimates, respectively. Precision increased with the increase in the coefficient of determination, the reduction in absolute errors, and the increase in the reproducibility of the estimates between pairs of raters.

摘要 本研究开发并验证了一套用于黄色西番莲果（Passiflora edulis）果实细菌性斑点病（Xanthomonas axonopodis pv.）严重度评估的标准区域图集（standard area diagram set, SADs）。该SADs包含8个严重度等级：1%、3%、5%、10%、21%、38%、65%及80%。为验证该图集的有效性，20名初始未借助SADs开展病害严重度评估的评估者被分为4组：G1与G3为无经验组，G2与G4为有经验组。随后，G1与G2未使用本研究提出的SADs完成第二次评估，而G3与G4则借助该标准区域图集完成第二次评估。评估的准确性与精密度通过简单线性回归及Lin一致性相关系数（Lin’s concordance correlation coefficient）进行测定。研究通过恒定误差与系统误差的降低证实了评估准确性的提升，表明使用SADs时，估测的病害严重度更接近真实值。无经验组评估者从SADs的应用中获益最为显著，其中60%的无经验评估者实现了无恒定误差的估测，100%的无经验评估者实现了无系统误差的估测。精密度则随决定系数的升高、绝对误差的降低以及评估者间估测重现性的提升而增强。