Rapid methods for selecting single kernels of waxy barley

Abstract

The rapid estimation of the amylose content in waxy barley is of particular importance in breeding new varieties with a low amylose content and in controlling the amylose content in the industrial production process, e.g. milling companies. Therefore, an amylose test measuring the quotient of the absorbance of the starch-iodine complex in the absorption maximum for amylose and for amylopectin was modifi ed and adapted for the determination in single kernels of commercial and waxy barley. To achieve this, single kernel were crushed, dissolved with 1N sodium hydroxide solution and stained with iodine-potassium iodide solution. Next, the amylose iodine and the amylopectin iodine complex were measured colorimetrically in wells of microtitre plates (96 samples). The modifi ed two-wavelength iodine binding procedure was used as a standard chemical analysis for developing a non destructive Near Infrared (NIR) method to distinguish single kernel of commercial barley and waxy barley. The calibration was calculated using the transmission spectra and the Modifi ed Partial Least Squares (MPLS)-method. Spectral transmission in a wavelength range between 900 nm and 1100 nm were measured in a cuvette holding 23 single kernels. The quality of the calibration was controlled by cross validation (coeffi cient of cross validation 1-VR = 0.936; standard error of cross validation SECV = 0.020) and a prediction (coeffi cient of prediction RSQ = 0.883; standard error of prediction SEP [C] = 0.028) in the range of R-Values between 0.63 and 0.86. Applying this calibration facilitates an unequivocal differentiation between commercial and waxy barley genotypes on the single kernel level.