Discrimination between seedlings of Eucalyptus globulus, E. nitens and their F₁ hybrid using near-infrared reflectance spectroscopy and foliar oil content

Abstract

SummaryIdentification of plant hybrids produced from closely related species can be difficult using morphological characteristics alone, particularly when identifying young seedlings. In this study, we compared the performance of three calibration models developed to discriminate between seedlings of Eucalyptus globulus, E. nitens and their first-generation hybrid using either foliar oil chemistry or near-infrared reflectance spectral data from fresh, whole leaves. Both oil and near-infrared reflectance spectroscopy (NIRS) models were developed using partial least-squares discriminant analysis and showed high classification accuracy, all correctly classifying more than 91% of samples in cross-validation. Additionally, we developed a larger, "global" and independently validated NIRS model specifically to discriminate between E. globulus and F 1 hybrid seedlings of different ages. This model correctly classified 98.1% of samples in cross-validation and 95.1% of samples from an independent test set. These results show that NIRS analysis of fresh, whole leaves can be used as a rapid and accurate alternative to chemical analysis for the purpose of hybrid identification.

Chemical Variation in a Dominant Tree Species: Population Divergence, Selection and Genetic Stability across Environments

“…These selected samples were representative of the spectral variation present in the entire sample set. Half of these samples (n = 50) were added to existing NIRS models [30] and these models were re-developed to predict the concentration of the samples used in this study. The other half of the samples (n = 50) were used as an independent validation set of the predictive models.…”

Field screening for genetic-based susceptibility to mammalian browsing

“…Additionally, further screening of native populations could find even more resistant seedlots that could potentially be added to the deployment stock. The other option is the pre-screening of seedlots for defensive chemistry in the nursery, perhaps using rapid screening techniques such as near infrared reflectance spectroscopy Humphreys et al, 2008). In the present case, defensive chemistry explained two thirds of the variation in browsing between seedlots.…”

Using near-infrared spectroscopy to discriminate closely related species: A case study of neotropical ferns

“…Also, the existence of hybrids between these species (Sota 1973) might explain the related spectral readings and the lower percentage of correct predictions. The technique has been shown to detect differences in the physical and biochemical compositions expressed in plant samples, even between closely related species, populations, and hybrids (Atkinson et al 1997; Cui et al 2012; Humphreys et al 2008).…”