Direct determination of nutrient elements in plant leaves by double pulse laser-induced breakdown spectroscopy: evaluation of calibration strategies using direct and inverse models for matrix-matching.

This study aims to develop a single calibration model to determine nutrient elements directly (Ca, Mg, Mn, and P) in soybean and sugar cane leaf samples by double pulse laser-induced breakdown spectroscopy (DP LIBS). Matrix-matching calibration (MMC) was evaluated using direct and inverse models. Forty-five samples were used to build the calibration model (23 soybean leaves and 22 sugar cane leaves), and fifteen were used for the prediction test (8 soybean leaves and 7 sugar cane leaves) models.

Evaluation of the Nutritional Changes Caused by Huanglongbing (HLB) to Citrus Plants Using Laser-Induced Breakdown Spectroscopy.

Huanglongbing (HLB) is the most recent and destructive bacterial disease of citrus and has no cure yet. A promising alternative to conventional methods is to use laser-induced breakdown spectroscopy (LIBS), a multi-elemental analytical technique, to identify the nutritional changes provoked by the disease to the citrus leaves and associate the mineral composition profile with its health status. The leaves were collected from adult citrus trees and identified by visual inspection as healthy, HLB-symptomatic, and HLB-asymptomatic.

Laser-induced Fluorescence Spectroscopy (LIFS) for Discrimination of Genetically Close Sweet Orange Accessions ( Citrus sinensis L. Osbeck).

Although there is substantial diversity among cultivated sweet oranges genotypes with respect to morphological, physiological, and agronomic traits, very little variation at DNA level has been observed. It is possible that this low DNA molecular variability is due to a narrow genetic basis commonly observed in this citrus group. The most different morphological characters observed were originated through mutations, which are maintained by vegetative propagation.