Comparison of Two Calibration Procedures for Predicting Leaf Percentages from Forage Sorghums and Pearlmillets Using Near-Infrared Reflectance Spectroscopy

A rapid method for determining leaf percentage (LP) from forage sorghums (Sorglium bicolor (L.) Moench) and pearlmillets (Pennisetum americaum (L.) Leeke) is reported. Our objective was to develop and compare two near-infrared reflectance spectroscopy (NIRS) calibration methods for predicting LP. Calibration methods developed were: I) leaves assigned a value of 99.99% leaf and 0.01 % stem, and stems a value of 99.99% stem and 0.01% leaf; and 2) ground leaf and stem samples mixed by weight to obtain a range of LP. Samples were scanned using NIRS and calibration equations developed. Equations had coefficients of multiple determination (R2) above 0.97. The R2 were higher and standard error of calibration lower for method 2 than for method I. Validation coefficients of determination ranged between 0.90 and 0.98 within years and 0.87 and 0.96 across years. Either calibration method is suitable for determining LP from forage sorghums and pearlmillets