Near infrared spectroscopy (NIR) and chemometrics methods to identification of haploids in maize

Haploids in maize are selected through visual analysis, whether by use of expression of the R1-navajo marker in seeds, or by the phenotype of haploid plants in the field. These methods of identification of haploid plants demand space, resources, and time. Near infrared spectroscopy (NIR), together with multivariate calibration methods, is an alternative for identification of haploid seeds and plants in a quick and accurate way. The aim of the present study was to use NIR to classify haploid and diploid seeds and differentiate haploid, doubled haploid, and diploid plants originating from different genotypes used as donor. In the first experiment, haploid and diploid maize seeds were analyzed from four genotypes used as parents. In another experiment, diploid, haploid, and doubled haploid plants from 34 source populations were evaluated and differentiated. Spectral data were collected from all the seed and leaf samples using the portable MicroNIR device. Then the data were preprocessed by principal component analysis and by partial least squares discriminant analysis (PLS-DA). The use of the portable MicroNIR, together with the PLS-DA method, enabled classification of haploid and diploid seeds and haploid, doubled haploid, and diploid plants with 100% accuracy, constituting a fast, simple, nondestructive, and reliable methodology for identification of haploids in maize, and it is more effective than the visual analysis.